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Graft copolymerization of acrylamide onto xanthan gum
Abstract
The graft copolymerization of acrylamide onto xanthan gum initiated by the Fe2+/BrO3− redox system in aqueous medium was studied gravimetrically under a nitrogen atmosphere. The effect of Fe2+, BrO3−, H+, acrylamide and xanthan gum on graft copolymerization was studied by determining the grafting parameters, i.e. grafting ratio, efficiency, conversion and add on. Homopolymer too has been separated out. An increase in grafting parameters was observed with increase in ferrous ion concentration (4×10−3moldm−3 to 5.0×10−3moldm−3) while with increasing bromate ion concentration, grafting ratio, efficiency, add on and conversion were found to decrease. It was observed that grafting takes place efficiently when acrylamide concentration and temperature were 4.0×10−3moldm−3 and 35°C, respectively.
... Its property can be customized and extended by hybridization with synthetic polymers. Acrylic acid (Pal, Majumder, & Bandyopadhyay, 2016), 2-acrylamido-2-methyl-1-propane sulfonic acid (Aflaki, Dadvand, & Sheykhan, 2016), ethylacrylate (Pandey & Mishra, 2011), acrylamide (AM) (Behari, Pandey, Kumar, & Taunk, 2001) and N-vinylpyrrolidone (Ding, Yiming, Yanjie, Bao, & Yongfu, 2016) have been grafted onto XG. The chemical amalgamation of natural and synthetic polymer resulted in a yield of new materials with superior properties. ...
... Kumar, Singh, and Ahuja (2009) synthesized matrix XG-g-poly(AM) that could be used as drug delivery system with a fast release of the active substance (Kumar et al., 2009). Behari et al. (2001) grafted AM onto XG to improve the thermal stability (Behari et al., 2001). Biswas, Pal, and Udayabhanu (2015) reported the grafted copolymer XG-graft-poly(AM) could be used as a corrosion inhibitor (Biswas et al., 2015). ...
... Kumar, Singh, and Ahuja (2009) synthesized matrix XG-g-poly(AM) that could be used as drug delivery system with a fast release of the active substance (Kumar et al., 2009). Behari et al. (2001) grafted AM onto XG to improve the thermal stability (Behari et al., 2001). Biswas, Pal, and Udayabhanu (2015) reported the grafted copolymer XG-graft-poly(AM) could be used as a corrosion inhibitor (Biswas et al., 2015). ...
... Many investigators functionalized different natural polysaccharides like locust bean gum (Kaity et al., 2013), guar gum (Abdel-Halim & Al-Deyab, 2011;Deshmukh & Singh, 1987;Jalababu, Satya Veni, & Reddy, 2019) and xanthan gum (Behari, Pandey, Kumar, & Taunk, 2001;Maia, Silva, Curti, & Balaban, 2012) through graft copolymerization of distinct vinyl monomers. The same has been tested for the purpose of drug delivery and wastewater treatment. ...
... When CAN was used as a initiator for the grafting of poly (acrylamide) onto XG, only 63 % grafting and 22 % grafting efficiency was obtained (Kumar et al., 2009). Similar results were obtained at the same acrylamide: XG weight ratio when Fe 2+ /BrO 3 − redox pair was used (Behari et al., 2001). Nonetheless, Ghorai et al. noticed that higher grafting efficiency (75-92 %) could be obtained relatively at low KPS concentration and higher temperature (70 • C) (Ghorai, Sinhamahpatra, Sarkar, Panda, & Pal, 2012). ...
Xanthan gum (XG) possesses numerous hydroxyl groups, which are the focal points for graft copolymerization of synthetic monomers. A detailed mechanism of graft copolymerization is of utmost importance in obtaining new materials with desirable attributes. The physicochemical, thermal, and morphological changes gained after graft copolymerization is also described. The graft copolymerization can further improve adsorption efficiency of toxic heavy metals and synthetic dyes from wastewater or industrial effluents. The swelling and pH-sensitivity of graft copolymer are attractive features for the purpose of controlled drug delivery. Despite a plethora of reports, comprehensive reviews on XG-based graft copolymers and their potential applications are scarce. Hence, this review undertakes detailed discussion on the synthesis of XG-based graft copolymer, their properties and potential application in drug delivery and wastewater treatment, which would be interesting for the readers and budding scientists to progress further with polysaccharide research and explore new materials for the intended purposes.
... The grafted copolymer gel can withstand different demerits for polymeric gel materials for conformance control treatments. Cassia tora gum, xanthan gum, carboxymethyl cellulose, and guar gum grafted polyacrylamide are already reported [13][14][15][16][17][18]. ...
... These permeability are incorporated to evaluate the gel plugging efficiency using Eqs. (10)- (14). ...
The injection of cross-linked polymer gels to block high permeability zones and divert subsequent water/surfactant flooding to low permeability streaks to improve hydrocarbon production efficiency is commonly known as profile modification. Moreover, in a reservoir condition with high temperature, pH, and salinity, these cross-linked polymeric gels are unstable, leading to early syneresis. In this research work, poly(Acrylamide)-grafted-xanthan gum copolymer was synthesized by free radical polymerization using potassium persulfate as an initiator. Field-Emission Scanning Electron Microscopy and Fourier Transform Infrared spectroscopy characterize the grafted copolymer in this study. This grafted copolymer, which is soluble in water, was cross-linked with a low toxic organic cross-linker. The organic cross-linker is composed of hexamethylenetetramine (HMTA) and hydroquinone (HQ). The rheological examination and gelation conduct of this polymeric gel was analyzed using a bottle test. The experimental design in response surface method generated a second-order polynomial equation for the gelation time responses to the change in the reservoir parameters (salinity, pH, and temperature) and their interactions. The results exhibited that the response surface model can be applied successfully to analyze gelation time with the various reservoir parameters. Laboratory prepared sand pack flow experiment demonstrated a decent diverting capability of the grafted copolymer gel than commercially used polyacrylamide gels. Subsequently, this grafted copolymer gel can be suitable for profile modification jobs required for improving oil recovery from mature oil fields with high reservoir heterogeneities.
... The structures of these polysaccharides are shown in Figure 6. The water-soluble polysaccharides mentioned above demonstrate a strong shear-thinning behavior (Tako et al. 1989, Wientjes et al. 2000, Behari et al. 2001, Chagas et al. 2004, da Silva et al. 2007, Maia et al. 2012, Xu et al. 2013, 2015a. The stretching macromolecules of the polysaccharide intertwine to form aggregates in the low shear rate. ...
... To overcome the demerits of polymers, numerous efforts have been made to combine the best properties of both polymers by grafting PAM onto the backbone of polysaccharides. Graft polymerization of acrylamide onto xanthan gum has introduced new material possibilities in EOR (Behari et al. 2001, Maia et al. 2012. The rheological behavior of the grafted copolymer has been compared with that of the parent xanthan gum and PAM. ...
A significant amount of oil (i.e. 60–70%) remains trapped in reservoirs after the conventional primary and secondary methods of oil recovery. Enhanced oil recovery (EOR) methods are therefore necessary to recover the major fraction of unrecovered trapped oil from reservoirs to meet the present-day energy demands. The chemical EOR method is one of the promising methods where various chemical additives, such as alkalis, surfactants, polymer, and the combination of all alkali–surfactant–polymer (ASP) or surfactant–polymer (SP) solutions, are injected into the reservoir to improve the displacement and sweep efficiency. Every oil field has different conditions, which imposes new challenges toward alternative but more effective EOR techniques. Among such attractive alternative additives are polymeric surfactants, natural surfactants, nanoparticles, and self-assembled polymer systems for EOR. In this paper, water-soluble chemical additives such as alkalis, surfactants, polymer, and ASP or SP solution for chemical EOR are highlighted. This review also discusses the concepts and techniques related to the chemical methods of EOR, and highlights the rheological properties of the chemicals involved in the efficiency of EOR methods.
... This biopolymer is widely used in a broad range of industries, such as foods, toiletries, oil recovery and cosmetics, to confer the required properties without affecting the taste of the final product. In foods, xanthan gum is used as thickeners, gelling, suspending agents, protective colloids, emulsion stabilization, among other applications [5,6]. ...
... The main advantage of the hybrid model proposed here is that it takes into account the variation in the parameters along the fermentation, as previously reported by Mazutti et al. [14] in modeling the inulinase production. The influence of the number of sub-intervals (1)(2)(3)(4)(5)(6)(7)(8) in the objective function values (Eq. 1) was also evaluated and the best results were obtained using 6 sub-intervals in the time domain (data not shown). Thus, 4 sub-intervals of 12 until 48 h and 2 sub-intervals of 24 until 96 h of fermentation were adopted. ...
This work is focused on hybrid modeling of xanthan gum bioproduction process by Xanthomonas campestris pv. mangiferaeindicae. Experiments were carried out to evaluate the effects of stirred speed and superficial gas velocity on the kinetics of cell growth, lactose consumption and xanthan gum production in a batch bio-reactor using cheese whey as substrate. A hybrid model was employed to simulate the bio-process making use of an artificial neural network (ANN) as a kinetic parameter estimator for the phenomenological model. The hybrid modeling of the process provided a satisfactory fitting quality of the experimental data, since this approach makes possible the incorporation of the effects of operational variables on model parameters. The applicability of the validated model was investigated, using the model as a process simulator to evaluate the effects of initial cell and lactose concentration in the xanthan gum production.
... This biopolymer is widely used in a broad range of industries, such as foods, toiletries, oil recovery and cosmetics, to confer the required properties without affecting the taste of the final product. In foods, xanthan gum is used as thickeners, gelling, suspending agents, protective colloids, emulsion stabilization, among other applications [5,6]. ...
... The main advantage of the hybrid model proposed here is that it takes into account the variation in the parameters along the fermentation, as previously reported by Mazutti et al. [14] in modeling the inulinase production. The influence of the number of sub-intervals (1)(2)(3)(4)(5)(6)(7)(8) in the objective function values (Eq. 1) was also evaluated and the best results were obtained using 6 sub-intervals in the time domain (data not shown). Thus, 4 sub-intervals of 12 until 48 h and 2 sub-intervals of 24 until 96 h of fermentation were adopted. ...
... Gellan gum is an anionic, bacterial exopolysaccharide, which consists of repeating tetrasaccharide units of -Dglucose, -D-glucuronic acid, and -L-rhamnose residues (Izumi et al., 1996). Grafting of polyacrylic materials onto polysaccharides such as xanthan gum (Behari et al., 2001), guar gum (Taunk and Behari, 2000), chitosan (Kim et al., 2000), sodium alginate (Tripathy et al., 1999), and cashew gum (da Silva et al., 2007) are well known in the art. The copolymers have been applied in the design of various stimuli-responsive drug delivery devices such as transdermal films (Mundargi et al., 2007a;Kulkarni et al., 2009;Kulkarni and Sa, 2009a), matrix tablets Mundargi et al., 2007b;Mandal et al., 2010), microspheres/hydrogel beads (Rokhade et al., 2007;Kulkarni and Sa, 2008b), and nanoparticles (Qian et al., 2006). ...
... Gellan gum is an anionic, bacterial exopolysaccharide, which consists of repeating tetrasaccharide units of -Dglucose, -D-glucuronic acid, and -L-rhamnose residues (Izumi et al., 1996). Grafting of polyacrylic materials onto polysaccharides such as xanthan gum (Behari et al., 2001), guar gum (Taunk and Behari, 2000), chitosan (Kim et al., 2000), sodium alginate (Tripathy et al., 1999), and cashew gum (da Silva et al., 2007) are well known in the art. The copolymers have been applied in the design of various stimuli-responsive drug delivery devices such as transdermal films (Mundargi et al., 2007a;Kulkarni et al., 2009;Kulkarni and Sa, 2009a), matrix tablets Mundargi et al., 2007b;Mandal et al., 2010), microspheres/hydrogel beads (Rokhade et al., 2007;Kulkarni and Sa, 2008b), and nanoparticles (Qian et al., 2006). ...
... Graft copolymers are a particular type of branched polymer that can produce unique features not found in the parent backbone [14]. Many researchers have found that adding vinyl monomers to XG and XG derivatives changes the structural features of virgin-based products [15][16][17][18][19][20][21]. ...
Xanthan gum has been modified by carboxymethylation to hamper its slow dissolution and then grafted with 4-vinyl pyridine (4-VP) in the aqueous phase using potassium persulphate (KPS) as an initiator aiming to obtain new biopolymer-synthetic hybrid materials with desirable Physico-chemical properties and antimicrobial activity. The influence of reaction parameters on grafting yield (G), grafting efficiency (GE), and homopolymer (H) percentage was investigated.
Maximum %G and low %H were obtained at concentrations of 1 mol L⁻¹ 4VP and 12 ×10⁻² KPS, respectively. The optimum temperature and reaction period were 60 °C and 120 (min.), respectively. FTIR, XRD, TGA and SEM techniques were used to confirm the structure, morphology and thermal stability of the prepared copolymers. TGA revealed that the CMX-g-P4VP is thermally more stable than the neat CMX. The influence of P4VP content in the copolymers and pH of the aqueous media on the swelling capacity was examined and the results revealed that swellability increased with the increasing P4VP content. The highest swelling capacity was achieved at pH =2.5 and %G of 420% reaching 7300%. The antimicrobial activity of the grafted copolymer was investigated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as Gram-negative and Gram-positive bacteria, respectively, in addition, Candida albicans (C. albicans) as fungus. The effect of P4VP content in the copolymers on the minimum inhibitory concentration (MIC) was evaluated and the results showed that the graft copolymer exhibited better biological activity compared with neat CMX and the MIC values decreased with increasing the P4VP content. Additionally, cytotoxicity of the graft copolymer was estimated against normal lung cell lines and found to be non-toxic and exhibiting IC50 > 500 µg/mL
... However, there was a slight increase in the homopolymer yield, suggesting the preference of the monomer to its own macroradical than for the one on the grafted chain, probably due to some steric hindrances. The same behavior was observed by other investigators whose results have been published in the literature [34,35]. ...
New grafted copolymers possessing structural units of 1-vinyl-3-(1-carboxymethyl) imidazolium betaine were obtained by graft copolymerization of N-vinylimidazole onto gellan gum followed by the polymer-analogous reactions on grafted polymer with the highest grafting percentage using sodium chloroacetate as the betainization agent. The grafted copolymers were prepared using ammonium persulfate/N,N,N′,N′ tetramethylethylenediamine in a nitrogen atmosphere. The grafting reaction conditions were optimized by changing one of the following reaction parameters: initiator concentration, monomer concentration, polymer concentration, reaction time or temperature, while the other parameters remained constant. The highest grafting yield was obtained under the following reaction conditions: ci = 0.08 mol/L, cm = 0.8 mol/L, cp = 8 g/L, tr = 4 h and T = 50 °C. The kinetics of the graft copolymerization of N-vinylimidazole onto gellan was discussed and a suitable reaction mechanism was proposed. The evidence of the grafting reaction was confirmed through FTIR spectroscopy, X-ray diffraction, 1H-NMR spectroscopy and scanning electron microscopy. The grafted copolymer with betaine structure was obtained by a nucleophilic substitution reaction where the betainization agent was sodium chloroacetate. Preliminary results prove the ability of the grafted copolymers to bind amphoteric drugs (cefotaxime) and, therefore, the possibility of developing the new sustained drug release systems.
... Reaction parameters which effect the percentage grafting were optimized to obtain maximum graft yield. Parameters such as reaction time, reaction temperature, initiator ratio, monomer concentration, pH and amount of solvent were optimized (Al-Hoqbani et al., 2014;Behari et al., 2001;Liu et al., 2006;Singha and Rana, 2012;Tripathy et al., 2009;Witono et al., 2012). Maximum graft copolymerization (500.7%) was achieved with reaction time, 180 min; reaction temperature, 60°C; initiator ratio, 0.5: 1.0; solvent volume, 40 ml; pH of medium, 7.0 and AN, 0.92 Â 10 À4 mol L À1 (Fig. 3a-f). ...
The current investigation highlights the synthesis of adsorption device MHa-g-poly(AN)-AE by graft copolymerization of acrylonitrile (AN) onto Holarrhena antidysenterica fiber in the presence of air along with Ferrous ammonium sulfate (FAS) and Potassium persulfate (KPS) initiators followed by quaternization process. Synthesized samples and backbone were studied using different techniques such as Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopic (XRD) and TGA/DTA/DTG studies. High efficiency of dye adsorption (99% of malachite green dye) was achieved using an initial dye concentration of 10.0 mg L⁻¹ with an adsorbent dose of 500 mg 50 ml⁻¹ within the time duration of 165 min at neutral pH and 25 °C. Adsorption data best fit with Langmuir Isotherm, pseudo second-order kinetics model and follow both macro & micro-pore intra-particle diffusion.
... (Fig. 11). A higher value of FDT corresponds to the crosslinking of poly(acrylic acid) and poly(vinyl acetate) chains and N,N'-methylene-bis-acrylamide onto IPN through graft copolymerization, which leads to more thermal stability in comparison to hybrid backbone [53]. The DTG curve of BGCP showed decomposition at 562.4 °C with weight loss rate of 0.614 mg/min. ...
In this paper, agar/gelatin and acrylic acid-co-vinyl acetate (monomer chains) based superabsorbent, fabricated using gamma radiations as an initiator and N-N′ dimethylene bisacrylamide as a crosslinker, has been investigated for its swelling behaviour (Max. Ps = 8010) in distilled water as a function of time, temperature and pH. The hydrogel has further been applied for sustained delivery of diethyl carbamazine citrate under three pH conditions at 37 °C. It has been found to show non-Fickian type mechanism as the drug release showed diffusion coefficient less than 0.50 for all the pH conditions. The gel characteristic constant ‘n’ was found to be: 0.910 at 9.2 pH, 0.832 at 7.0 pH and 0.768 at 2.2 pH with their corresponding ‘k’: 0.175, 0.242 and 0.413, respectively. The initial diffusion coefficient has been found to show greater values than late diffusion coefficient confirming greater release at the early stages of the drug release than that in the late stages. Also to apply BGCP in soil treatment its moisture retention capacity has been studied using three different soil models. BGCP was found to retain moisture under clay, mix and sand soil models for 57 days, 42 days and 32 days, respectively. Under bio-composting method of biodegradation sample was found to be 91% degraded after 70 days.
... In such cases graft copolymer is precipitated by using appropriate precipitating agent, and homopolymer is also separated. This method of parting has been successfully applied in many systems [19][20][21][22][23][24][25][26][27]. However, if it is not possible to separate the homopolymer from graft copolymer, such products are referred to as composites. ...
... Grafting reactions carried out in aqueous media by radical mechanisms represent a very useful tool for modifying natural polymers due to the possibility of achieving desired properties. This promising technique for the chemical modification of biopolymers through functionalization has gained a lot of attention in recent years due to the ability to tune these polymers by precise approaches for a target application domain [1][2][3][4][5]. The chemical modification of polymers with vinyl monomers has been performed by different mechanisms [6][7][8][9]. ...
This paper reports the synthesis and complex characterization of novel polymeric networks based on the crosslinking of Bombyx mori silk fibroin via poly(N-isopropylacrylamide) bridges generated by an ammonium cerium nitrate redox system. The research study gives an understanding of the polymerization mechanism in terms of the generation of radical sites, radical growth and termination reaction, as well as the involvement of modifications on silk fibroin structure and properties. The physico-chemical characterization was carried out by FTIR-ATR, X-ray photoelectron spectroscopy and RAMAN spectroscopy with unravelling the chemical modification. The structural characterization and spatial arrangement by secondary structure were carried out by X-ray diffraction and circular dichroism. The thermal behavior and thermal stability were evaluated by differential scanning calorimetry and thermogravimetric analysis. The novel complex polymer network is intended to be used in the field of smart drug delivery systems.
... In this domain, controlled release systems allowing controlled and targeted escape of a drug have been widely studied. [1][2][3][4][5][6][7][8][9][10][11][12] Hydrogels are a promising approach in numerous pharmaceutic and biomedical applications because of their capacity to retain high water contents, their ease of handling, etc., even if biocompatibility is an important point which, in some cases, has to be overcome. 13,14 Such hydrogels may be prepared through chemical or physical crosslinking. ...
Gellan and xanthan are extracellular polysaccharides with very interesting rheological or gelling properties. They are esterified with acrylic acid, acryloyl chloride or maleic anhydride. Consequently, due to the presence of carbon double bonds, hydrogels are obtained using a grafting–crosslinking process with N‐isopropylacrylamide and N′‐bisacrylamide. Such hydrogels, due to the presence of poly(N‐isopropylacrylamide), are thermosensitive and present drug release properties which can be adjusted through the reaction conditions. This concept was demonstrated for ophthalmic applications. © 2019 Society of Chemical Industry
... Whereas, semi-IPN exhibited IDT and FDT at 208.8 C and 628.9 C; respectively. A higher value of FDT corresponds to the cross-linking of polyacrylic acid chains onto the hybrid backbone through graft copolymerization and N,N'methylene-bisacrylamide which leads to thermal stability [43]. TGA data of hybrid backbone and cross-linked semi-IPN showed weight loss near 200 C which can be due to the exclusion of water molecules and other unstable volatile components. ...
The present work deals with the fabrication of decomposable, agar-gelatin based semi-IPN superabsorbent which was cast-off as template for the synthesis of bioactive nano-hydroxyapatite. Microwave assisted free-radical polymerization technique was used and the optimized reaction parameters were: initiator (mol/L): 0.021; time (sec): 15; microwave power (%): 100; AA (mol/L): 6.994; MBA (mol/L): 6.4 × 10⁻³; solvent (ml): 12.5 and pH: 7.0. Semi-IPN could imbibe water to a large extent and maximum percentage swelling found was 4750%. The synthesized semi-IPN was used as mineralization matrix for the fabrication of rod-shaped nano-hydroxyapatite crystals which showed Ca/P ratio 1.665 similar to natural bone (1.67) with average crystallite size 50–100 nm (length) and 15–30 nm (diameter) respectively. Further soil water retention studies revealed that synthesized semi-IPN template could retain moisture for about 55 days, 40 days and 31 days in clayey, mix-soil and sandy soil, respectively and degraded upto 84% in 70 days using composting and 80% using vermi-composting method of biodegradation. Thus, synthesized device being antibacterial, biodegradable and ecofriendly could have a contribution in ever-green revolution also used as template for the morphology controlled synthesis of n-HA.
... Recently, graft copolymers of natural polysaccharides and synthetic polymer have been reported to enhance the physical properties of polymers. Graft copolymerization of natural polymers with functional synthetic polymers gives modified products having a wide range of applications due to combining in one molecule the desired properties of both the natural polymer and the synthetic polymer (Behari et al. 2001;Biswal and Singh 2004;Maia et al. 2012;Pandey and Mishra 2011). Graft copolymerization is an easy method to modify the structure of natural polymers and thus makes them suitable for various applications such as flocculants (Ghorai et al. 2013;Sen et al. 2011), controlled drug release (Namazi and Belali 2015) and petroleum recovery treatments (Singh and Mahto 2016b;Song and Zhang 2007) of mature reservoirs. ...
In this paper the suitability of a graft polymer nanocomposite hydrogel system for enhanced oil recovery was examined using polyacrylamide graft starch/clay nanocomposite (a laboratory synthesized product) and chromium (III) acetate (crosslinker). X-ray diffraction analysis, Fourier transform infrared spectrometry analysis, field-emission scanning electron microscopy and transmission electron microscopy were carried out to reveal the laboratory synthesized product as a nanocomposite. The effects of various parameters like salt concentration, pH, temperature, polymer concentration and crosslinker concentration on the properties of the developed gel system were systematically evaluated. The thermal stability of the nanocomposite gel and the conventional gel system were also determined by thermogravimetric analysis. The graft polymer nanocomposite gel system exhibited acceptable gel strength, gelation time and gel stability compared with the conventional gel system. The nanocomposite gels prepared using a low crosslinker concentration showed higher gel strength and required longer gelation time than the conventional gel which is more desirable properties for the effective placement of gel during enhanced oil recovery operations. In addition, sand pack flooding experiments show that the graft polymer nanocomposite gels had better plugging capacity than the conventional gel systems under reservoir conditions. Hence, this gel system may be suitable in the water shutoff treatments required for enhanced oil recovery from oilfields.
... Here, a decrease in the second decomposition temperature of the grafted copolymer was observed as the polyacrylamide chain degraded within the temperature range 175 1C to 300 1C by the evolution of ammonia and the formation of an imide group. 51 This formation of an imide group also gives thermal stability to the graft copolymer, as above 27% of weight loss the graft copolymer (F 1 ) is more stable than the guar gum. The grafted copolymer (F 1 ) exhibited another two regions of weight loss from 335 1C to 460 1C and from 461 1C to 590 1C, due to the decomposition of the grafted polyacrylamide chain. ...
Recently transdermal drug delivery systems (TDDS) based on polymeric nanocomposites have been widely researched by polymer and biomedical scientists for the remedy of various diseases. Thus to develop an efficient patch, we have synthesized guargum-g-polyacrylamide by free radical polymerization using potassium persulphate as an initiator. The transdermal membranes were fabricated via solution casting, by incorporating different wt% of nanosilica and diltiazem hydrochloride to the synthesized copolymer. The resulting copolymer and the nanocomposite membranes were characterized using solid state 13C nuclear magnetic resonance, Fourier transform infrared spectra, thermo-gravimetric analysis, electron microscopy and viscometry. Hydro-swelling study and surface contact angle measurement showed that the membrane containing 1 wt% nanosilica was most hydrophobic. In-vitro drug release pattern of all the transdermal membranes showed that the nanocomposite containing 1 wt% nanosilica provide the best result with 8.58 and 24.76% drug release after 5 and 20 h, respectively. Furthermore, the nanocomposite formulation exhibited good cyto-compatibility and non-irritant behaviour which are primary requirement for an efficient transdermal drug delivery system.
... NPs are suitable for the controlled and targeted delivery of anti-cancer drugs to tumor by enhanced permeation and retention (EPR) effect [219,220]. Anirudhan et al. [77] prepared dextran based nano sized carrier for the controlled and targeted delivery of curcumin to liver cancer cells by graft copolymerization from 2-hydroxyethylmethacrylate (HEMA) and glycyrrhetinic acid (GA), (Fig. 9a) [221,222] using ethylene glycol dimethacrylate (EGDMA) ...
... In addition, graft copolymerization contributes hydrophobic character and add stearic bulkiness, which considerably protects carbohydrates backbone that results in increase solution viscosity, improve flocculation efficiency , retard drug release, decolorize textile dyes, enhance the shear stability, impart resistance to biological degradation and super adsorbent property (Jiang et al., 2006; Mundargi, Patil, & Aminabhavi, 2007; Singh, Tiwari, Tripathi, & Sanghi, 2004; Sanghi, Bhattacharya, & Singh, 2006; Toti & Aminabhavi, 2004). This probably the reason for the efforts made to achieve best possible graft copolymer onto the polysac-charide backbone like guar gum (Singh et al., 2004), acacia gum (Toti & Aminabhavi, 2004), cassia tora gum (Sharma, kumar, & Soni, 2002), tamarindus indica mucilage (Mishra, Bajpai, Pal, Agrawal, & Pandey, 2006), kundoor mucilage (Mishra & Bajpai, 2005 ), xanthan gum (Behari, Pandey, Kumar, & Taunk, 2001), carboxymethyl cellulose (Tame et al., 2011), Sodium alginate (Kurkuri, Kumbar, & Aminabhavi, 2002), amylopectin (Adhikary & Krishnamoorthi, 2013), starch (Pledger Jr., Young, Wu, Butler, & Hogen-Esch, 1986), carboxymethyl starch (Cao, Qing, Sun, Zhou, & Lin, 2002), chitosan (Al-Karawi, Al-Qaisi, Abdullah, Al-Mokaram, & Al-Heetimi, 2011), carrageenan (Darmayanti & Radiman, 2015) and cashew gum (da Silva, de Paula, & Feitosa, 2007). However, no attempt has been made to graft arabinoxylans (e.g. ...
... In the present investigation, we have modified xanthan gum (XG), a naturally occurring high molecular weight microbial polysaccharide by carboxymethylation, as the derivatisation which enhanced the behaviour of XG toward grafting due to the collective influence of the following factors firstly, presence of carboxymethyl groups improves the solubility of XG, facilitating diffusion of the monomer and initiator thereof, and secondly, the ionisation of carboxyl groups along with XG chains introduce a negative charge, attracting the initiator ions towards the XG molecules which leads to the formation of more active sites, available for the monomer, thus increasing reactivity of XG. Literature survey reveals that recently, a good amount of work on grafting of AAm onto XG using different initiating systems has been carried out [11][12][13][14]. However, the data on grafting of AAm onto carboxymethyl xanthan gum (CMXG) are scanty. ...
In the present work, an unreported graft copolymer of carboxymethyl xanthan gum and acrylamide has
been synthesised by free radical polymerisation in a nitrogen atmosphere using ammonium persulphate
as an initiator. The optimum reaction conditions adopted for affording maximum percentage of grafting
including its grafting efficiency were obtained by varying the concentration of carboxymethyl xanthan
gum from 4 to 24 g dm−3; ammonium persulphate from 5 × 10−4 to 30 × 10−4 mol dm−3; acrylamide from
0.4 to 1.2 mol dm−3; reaction temperature from 55 to 75 ◦C and reaction time from 30 to 90 min. The
synthesised graft copolymer has been characterised by 1H NMR, FTIR spectroscopy, X-ray diffraction
measurement, thermal analysis, viscosity measurement and scanning electron microscopy. However,
grafting of acrylamide onto carboxymethyl xanthan gum backbone enhanced its thermal stability. This
graft copolymer might be well exploited globally as a potential carrier for drug delivery system
... The novel products with wide range of applications are obtained by grafting of synthetic polymers onto biopolymers. Such chemical modification yields new molecules with appropriate properties of both biopolymer and synthetic polymer [6][7][8][9][10][11][12] .Polymers are usually synthesized by conventional grafting method [13][14][15][16][17][18] , microwave irradiation [19][20][21][22] , γ-ray irradiation [23][24][25][26] , and using electron beam [27][28] . Grafting with conventional procedures may lead to polysaccharide backbone degradation and are not responsive to block copolymer formation 29 . ...
Industrial and municipal waste frequently contain metal ion, of which, industrial waste constitutes the major source of pollution in natural water. An abstraction of these colloidal metal particles from wastewaters becomes a serious challenge for the industries. Attention has been increasingly paid to natural polymer flocculants owing to their wide availability, biodegradability, and environment-friendliness. In the present investigation, polyacrylamide grafted guar gum (GG-g-PAAm) was synthesized using microwave assisted method in the presence of ceric ammonium nitrate (CAN) as an initiator. The synthesis was optimized for highest percentage grafting by varying the microwave irradiation time, power, initiator, and monomer concentration. Characterization of the grafted product was performed by the FTIR and TGA methods. The copolymer resulting from the graft copolymerization reaction was subsequently treated with gluteraldehyde (GA) to obtain crosslinked hydrogel. Further, flocculation efficacy of crosslinked hydrogel was studied by standard 'Jar test' procedure in 0.25% kaolin suspension, to assess its application as flocculating agent for wastewater treatment.
Gums are natural source available in plants. Which are originally low cost and abundant. It has various applications as viscosifiers, thickeners, emulsifiers, sweeteners etc. in confectionary, and as binders. It can be used in drug release modifiers in pharmaceutical dosage forms. But the problem associated with natural gums is that it is required in very high concentrations to successfully function as drug release modifiers in dosage forms due to their high swell ability/solubility at acidic pH. So it is needed gums need to be modified to alter their physicochemical properties. This article is involved discussing for the modification gums techniques like grafting reaction, carboxymethylation, esterification, oxidation reaction etc. These techniques are modifying natural gum and can be helpful for drug release properties of pharmaceutical dosage forms.
The gene delivery system offers a platform that is easily modified by upregulation or downregulation of gene expression in cellular aspects to treat diseases in pathological environments. To achieve this goal, various intracellular and physiological barriers need to be overcome to reach the targeted cells. In this context, chitosan is an exceptional candidate that efficiently delivers different genes to treat various diseases due to its extraordinary properties such as high biodegradability, positive surface charge, low immunogenicity, and high biocompatibility. However, low transfection ability remains a concern. Researchers are continuously focusing on the development of different formulations, incorporation of functional group, size, and different shape in chitosan-based gene delivery to achieved therapeutic efficiency. This chapter focuses on gene therapy, chitosan-based gene delivery, strategies to improve chitosan-based gene delivery, and its limitation as well as challenges.
In recent studies, polysaccharide-based advanced composite materials applied in biological science have been in high demand because they are biocompatible, inexpensive, and naturally available. These are a long chain of polysaccharide, containing many monosaccharides that are linked to the glycosidic bonds, and are a promising alternative to nonbiodegradable chemical polymers due to biodegradability and sustainability in the ecosystem. Natural polysaccharide has been used to prepare nanocomposite material with metal oxide and carbon-based nanomaterials. The surface area/volume ratio is crucial to understand nanocomposite’s structural property based on polysaccharide. Different types of monosaccharides and polysaccharides from various biological sources, at a nonmetric scale, have been used for the synthesis of nanocomposite materials with low density, high molecular weight, high surface reactivity, and ease of surface modification. There are signs of progress with these materials in preclinical applications for tissue engineering and gene delivery to treat many diseases in both therapeutic and monitoring aspects. These nanocomposite materials can potentially be used in tissue engineering, drug delivery, cellular culture, and any medicine’s slow release. This chapter focuses on the application of nanocomposite materials in tissue engineering and gene delivery.
Xanthan gum (XG) is a naturally occurring exo-polysaccharide produced by the class of bacteria Xanthomonas campestris. This hetero polysaccharide produced from Gram-negative bacteria has various unique properties such as biocompatibility, biodegradability, cytocompatibility, highly viscous and pseudo-plastic nature, nontoxicity, and solubility in both cold and hot water, which make it a promising agent in biomedical and tissue engineering applications. Traditionally, XG is an important component for various industrial and biomedical applications as a thickener, emulsion stabilizer, and additive, and is widely used in food and food packaging, cosmetics, toiletries, drug delivery, etc. Recently, it has been used in tissue engineering applications after undergoing various chemical and physical modifications through incorporation of NPs. In this chapter, we discuss the applicability of XG nanocomposites obtained through various modifications in the field of biomedicine and tissue engineering.
Natural polymers are hydrophilic in nature, economic, chemically inert, easily available, biodegradable, and non-toxic. Following problems associated with the use of gums include uncontrolled rates of hydration, pH dependent solubility, thickening, drop in viscosity on storage, and the possibility of microbial contamination. Chemical modification of gums not only minimizes these drawbacks but also alter their physicochemical properties. Recently, researchers have been modifying properties of natural gums to explore its more applicability. Aim of the current study was to explore Xanthan gum's applicability in mucoadhesive and other property by doing its Chemical modification. Sulfoxy amine modification of xanthan gum was carried out by reacting xanthan gum with thionyl chloride and further treated with ammonia. FTIR, elemental DSC, XRD and SEM were studied for confirmation of the modification. The modified xanthan gum showed improvement in the mucoadhesion, water uptake capacity, gelling property as well as viscosity as compared to unmodified xanthan gum. The results of X-ray diffraction study confirms the finding of DSC study. X-ray diffractogram confirmed XG is typical of amorphous substance while that of MXG is typical of crystalline substance with the characteristic peak appearing at 14.79, 25.66, 29.63 and 31.82 2θ. The 0.6% w/v of modified xanthan gum showed gelling property. The 0.6% w/v of modified Xanthan Gum showed gelling property where as Xanthan Gum required more than 1% w/v , it indicate that gelling property of Xanthan Gum has improved due to its modification. Mucoadhesive strength of modified xanthan gum was found to be 4±0.56 gm which is more than xanthan gum i.e. 1.5±0.94 gm. The ionic interactions may be taken place in between negatively charged mucus with cationic modified polymer and superior mucoadhesion can be achieved. Rapid and constant swelling behavior was observed by modified Xanthan gum. The SEM image of MXG showed that the grafting of Polysulfoxyamine onto XG brings about the change in the shape and size of the XG particles. The enhanced viscosity and gelling capacity of modified xanthan gum were also observed as compared to xanthan gum. In vivo acute toxicity study of Poly sulfoxy amine grafted xanthan gum was performed. The toxicological effects were observed in terms of mortality and expressed as LD 50. Results of Acute toxicity study shows LD 50 value was more than 2 gm/kg indicating the low toxicity. These findings proved that modified xanthan gum may be used as promising excipient in various drug delivery systems.
Biopolymer Xanthan gum (XG), an exo-polysaccharide obtained from the fermentation of simple sugars by bacteria Xanthomonas campestris under aerobic conditions exhibits interesting properties like biodegradability, high viscosity at a low shear rate and stability under a wide range of temperature and pH. These characteristics properties render it accessible to utilize as a stabilizer, suspending as well as an emulsifying agent in food industries, petroleum and oil refining industries, cosmetic industries, and as an adsorbent in wastewater treatment. However, XG hydrophilicity and water solubility characteristics not only restrict its application domain but also affect its thermal stability during processing. Therefore, the efforts are directed to improve its application spectrum by modifying the physical and chemical characteristics of biopolymer, taking advantage of the presence of different amenable functional moieties in XG. The chemical modifications of XG include the formation of cross-linked polymers, grafting of monomer to base polymers manipulating the functionality by removal/addition of chemical groups. Currently, the emphasis is on the development of XG based grafted/crosslinked bionanocomposites which can be tailored as a noble adsorbent for wastewater treatment for the remotion of toxic metals, coloured synthetic dyes and other industrial effluents from the aqueous medium. The emphasis of present review article is to address the structural, physical characteristics along with the focus on the development of chemically modified XG viz. grafted, crosslinked, nanocomposites, and functionally modified biopolymer. The potential applications of these modified XG polymers for phasing out synthetic dyes and transition metals ions from aqueous systems have been deliberated.
The study is mainly focused on the synthesis of polyacrylamide grafted cashew gum (CG-g-PAM) biocompatible graft copolymer as polymeric scaffold for tissue growth by free radical assisted microwave irradiation method using varying quantities of redox initiator ammonium persulfate (APS) for synthesis of CG-g-PAM graft copolymer and final copolymer was precipitated in presence of excess of acetone to remove the homopolymer and other unreacted monomer and byproducts. Percentage grafting efficiency (%GE) was selected as the optimization parameter for best grade. Various analytical techniques like fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA) studies were utilized for analyzing optimized grade GFS-3 The inserted grade GFS-3 in mice model showed satisfactory tissue growth over it ensuring biocompatibility along with evidences of nontoxicity on local tissue as well as on major organs like liver and kidney upon oral administration respectively. Moreover, GFS-3 was found to be hemocompatible in presence of mice blood.
In this report, we intended to synthesize chelating grafted copolymer of gum ghatti with acrylonitrile (Gg-g-An) by gamma irradiation as proficient and influential adsorbent for removal of uranyl ions. These grafted and modified copolymers were characterized using different techniques viz. FTIR, Elemental analysis, TGA and FESEM. Maximum grafting was accomplished with 5% gum ghatti solution and 1:3 ratio of acrylonitrile to backbone at 25 kGy total radiation dose. Surface area of grafted copolymer was calculated by BET analysis. Adsorption experiments reveal the adsorption capacity was effectively influenced at pH 6 with maximum adsorption 94% which substantiated Gg-g-AO surface engross excellent potential as chelating agent for adsorption of uranyl ions. Uptake of uranyl ions by Gg-g-AO was confirmed using spectroscopic and EDX analysis. The result showed that the pseudo second order reaction and Langmuir adsorption isotherms had remarkable conformity through linear fit statistics with r² 0.998 and 0.978 respectively. Furthermore, the thermodynamic parameters illustrated that the uranyl ions adsorption process by Gg-g-AO was endothermic and spontaneous. Desorption studies of Gg-g-AO confirmed the reusability up to three cycles in 0.1 M HCl. This study substantiated that the synthesized Gg-g-AO has impending use in environmental remediation.
Les polysaccharides amphiphiles sont constitués d’un squelette hydrophile sur lequel sont greffés des groupements hydrophobes. Ils possèdent des propriétés rhéologiques accrues dues à leur capacité d’auto-organisation en solution aqueuse mais également interfaciales dues à leurs propriétés d’adsorption aux interfaces eau/huile. Néanmoins, peu d’études s’intéressent à conférer ce type de propriétés à des polysaccharides complexes en termes de structure ou de conformation, comme le xanthane. En effet, ce polymère adopte en solution deux conformations distinctes selon les conditions expérimentales : une forme ordonnée hélicoïdale rigide et une forme désordonnée de type pelote flexible.Partant de ce constat, l’objectif de ce travail de thèse est de déterminer l’impact de la rigidité du squelette du xanthane modifié hydrophobiquement sur les propriétés amphiphiles en solution mais également sur les propriétés stabilisantes en émulsion.Il s’avère que la conformation adoptée par le polymère pendant le processus de greffage a un impact majeur sur ses propriétés rhéologiques : le xanthane modifié sous forme désordonnée possède un caractère associatif, contrairement au xanthane modifié sous forme ordonnée.De plus, le xanthane modifié hydrophobiquement est capable, sous certaines conditions, de former et de stabiliser des émulsions H/E, sans ajout de tensioactif moléculaire, en se partitionnant entre stabilisation de l’interface eau/huile et maintien de la viscosité de la phase aqueuse continue.
Hydrogels are three-dimensional structure composed of organic resources with lightly cross-linked having high to very high swelling ability in aqueous solutions. Due to the special physical and chemical properties of hydrogels, such as: flexibility, swell-ability, softness, and biocompatibility, there are growing research interest in the hydrogel synthesis, developing its properties, and hence increasing the applications in different fields. Both natural and synthetic polymers either physically or chemically cross-linked for producing hydrogels. This review covers definition, classification, application of polymer hydrogels and an also, overview of the different synthesis processes, kinetics and thermodynamics mathematical modeling approaches. A case study related to producing and using hydrogel in various areas has been reviewed.
A novel hydrogel was synthesized through the graft copolymerization of acrylic acid (AA) and acrylamide (AM) onto sodium alginate with ammonium persulfate as the initiator, methylene bisacrylamide as the crosslinking agent, and calcium chloride as the precipitating agent. Rapeseed meal biochar made at 300 °C was also used. A series of graft copolymers with various molar ratio of AA to AM was prepared. The structures of the hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The free absorbency and rate of release were investigated. The grafting efficiency increased as the concentration of AM increased. There was a considerable percentage of nitrogen in the graft copolymers, and the release rate of nitrogen from fertilizer in soil and water decreased with increasing concentration of AM. The water retention of soil without hydrogel remained at 63 and 53.4% on the 10th and 20th days, but with the hydrogels, it was above 70% even on the last day. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45966.
Tamarind gum is a plant polysaccharide extracted from seed endosperm of the plant, Tamarindus indica Linn. (Family: Fabaceae). It is a neutral, nonionic, and branched polysaccharide having water solubility, hydrophilic, gel-forming, and mucoadhesive properties. In addition, tamarind gum is biodegradable, biocompatible, noncarcinogenic, and nonirritant. Tamarind gum is employed as a potential biopolymer in the fields of pharmaceutical, cosmetic, and food applications. In the recent years, it is widely tested and employed in various drug delivery applications as effective pharmaceutical excipients. Tamarind gum is being exploited in the formulation of oral, colon, ocular, buccal, and nasal drug delivery systems. Though tamarind gum is extensively used in various drug delivery formulations, it has some potential drawbacks such as unpleasant odor, dull color, poor solubility in water, tendency of fast degradability in aqueous environment. To overcome these restrictions, tamarind gum has been functionally derivatized through chemical treatment with a variety of functional groups such as carboxymethyl, acetal, hydroxyl alkyl, thiol, polymer grafting, etc. Recently, various functionally derivatized tamarind gums hold a great promise as potential pharmaceutical excipients in different kinds of improved drug delivery systems mainly because of its improved stability (lower degradability). These functionally derivatized tamarind gums hold enhanced mechanical behavior as well as competence in prolonged period-controlling drug releases. The present chapter contends with a broad review of different kinds of functionalizations of tamarind gum for their use in the development of various improved drug delivery systems. The first part includes sources, compositions, properties and uses of tamarind gum. Then, the latter part contains a comprehensive review of different functionalizations of tamarind gum in drug delivery.
Xanthan gum is a microbial high molecular weight exo-polysaccharide produced by Xanthomonas bacteria (a Gram-negative bacteria genus that exhibits several different species) and it has widely been used as an additive in various industrial and biomedical applications such as food and food packaging, cosmetics, water-based paints, toiletries, petroleum, oil-recovery, construction and building materials, drug delivery. Recently, it has shown great potential in issue engineering applications and a variety of modification methods have been employed to modify xanthan gum as polysaccharide for this purpose. However, xanthan gum-based biomaterials need further modification for several targeted applications due to some disadvantages (e.g., processing and mechanical performance of xanthan gum), where modified xanthan gum will be well suited for tissue engineering products. In this review, the current scenario of the use of xanthan gum for various tissue engineering applications, including its origin, structure, properties, modification, and processing for the preparation of the hydrogels and/or the scaffolds is precisely reviewed.
Present work offers use of semi-interpenetrating network (semi-IPN) and interpenetrating network (IPN) as the template for the synthesis of nano-hydroxyapatites. Semi-IPN and IPN of agar-gelatin were prepared and successfully used to synthesize nano-hydroxyapatite. Graft copolymerization technique was used to alter the properties of the hybrid backbone using ammonium persulphate as an initiator and N,N'methylene-bisacrylamide (MBA) as a crosslinker. The first step was to synthesize cross-linked semi-IPN of agar-gelatin blend which was converted to a cross-linked interpenetrating polymer. Semi-IPN and IPN showed 4786% and 4896% swelling, respectively. In the second step in situ synthesis of rod-shaped nano-hydroxyapatites was carried out. Ca/P ratio for hydroxyapatite formed was found to be 1.67 for semi-IPN and 1.63 for IPN with the particle size of 50-100nm (length) and 6-15nm (diameter). These results were than compared with the literature findings of synthesizing n-HA (nano-hydroxyapatite) without using templates and results were better for n-HA synthesized using templates. Thus, the use of semi-IPN and IPN for the controlled growth of rod-shaped nano-hydroxyapatite was a novel approach.
Herein, a new adsorbent was synthesized by modifying xanthan gum for the removal of Cu2+ fromwastewater. Xanthan gum was first successfully modified with thionyl chloride followed byethylenediamine. The modified xanthan gum was characterized via Fourier transform infraredspectrometry (FTIR), carbon nuclear magnetic resonance (13C NMR), scanning electron microscopy (SEM),energy dispersion spectroscopy (EDS) and thermogravimetry (TG) for a better understanding of its Cu2+removal efficiency. In addition, the effects of pH, contact time, adsorbent dosage, initial concentration ofCu2+ and coexisting ions on the adsorption of Cu2+ were investigated via batch adsorption studies.
Results suggest that the adsorption process of Cu2+ follows a pseudo second order kinetics model withan equilibrium time of 120 min. The experimental data could be fitted with the Langmuir isotherm better than the Freundlich model. The adsorption capacity of Cu2+ by the modified xanthan gum reached up to46.95 (mg g_1). The adsorbent could be easily regenerated by only the addition of 0.1 M HCl. Also, the adsorption effect of other divalent cations by XG-NH2 was preliminarily investigated.<br/
Gum polysaccharides are one of the most abundant bio-based polymers. They are generally derived from plants as exudates or from microorganisms and have diverse applications in many industries, especially in the food industries where they are used as emulsifiers and thickeners. In their natural form, gum polysaccharides have poor mechanical and physical properties; therefore, they are frequently modified with various synthetic monomers such as acrylamide and acrylic acid using graft copolymerization. Graft copolymerization is one of the most trusted and widely used synthetic methods for the modification of gum polysaccharides. Gum polysaccharides modified in this way have improved mechanical and physicochemical properties. Furthermore, gum polysaccharides contain a variety of functional groups, for example, carboxylic acid and hydroxyl groups; therefore, they have been used extensively as adsorbents for the removal of different impurities from wastewater such as toxic heavy metal cations and synthetic dyes. Here, the chemical and physical properties of gum polysaccharides, different methods of graft copolymerization, and the use of graft copolymer gum-polysaccharide-based hydrogels are reviewed in detail for the removal of toxic heavy metal cations and synthetic dyes from aqueous solutions.
Atrazine is more reliable, effective and less expensive herbicide than any other available weed control approach. However, its easy leaching is matter of great environmental and health concern which limits its strong recommendation for practical applicability. Hence, in the present work atrazine containing agar/starch/poly(AAm) hydrogels have been prepared for its slow delivery applications. These hydrogels have been characterized by scanning electron micrography, Fourier transform infrared spectroscopy, X-Ray diffractometry and swelling studies. Hydrogels prepared at optimum reaction conditions (1 % agar, 5 % starch, 0.98 M acrylamide, and 12.97 mM N,N-methylenebisacrylamide) has shown maximum swelling 551.5 %. The release of atrazine from the hydrogels occurred through non-Fickian diffusion mechanism. The controlled release has been observed for 144 hours. High polymer matrix swelling and slow release make these hydrogels suitable for agricultural applications.
The main objective of this research work is to synthesize crosslinked hydrogel from xanthan gum and acrylamide under the influence of microwave radiations by graft polymerization technique in presence of potassium persulphate-N,N'-methylene-bis-acrylamide as initiator-crosslinker system. Different reaction parameters such as reaction time, pH, solvent and initiator concentration were optimized a function of percentage grafting. Monomer and cross-linker concentrations were optimized as a function of percentage swelling for getting the polymer with maximum water absorption capacity. The superabsorbent was characterized using different characterization techniques like, FTIR, TGA / DTA / TDG and X-ray diffraction. The candidate polymer was found to be thermally more stable than the xanthan gum.
Hydrogels are three dimensional crosslinked architectures with proven multifaceted applications. Nature has utilized these structured biomaterials instrumentally as mucus, vitreous humor, cartilage, tendons and blood clots. Thanks to the unique properties of hydrogel which could be tailored to apply them into different field of pharmacy, pharmaceutics and biomedical engineering. Hence the methods of hydrogel preparation and careful evaluation of properties are of utmost significance. Based on literature survey, preparation methods of hydrogels may also be classified on the basis of starting materials. Thus, hydrogels may be prepared from monomers, pre-polymers and polymers. Physical and chemical crosslinking methods are involved in the production of hydrogels for intended application. Physically developed hydrogels though less strong when compared with chemically crosslinked hydrogels, but free from unwarranted use of toxic chemicals. Physically crosslinked hydrogel formation is attributed to bonds formed by crystalline junctions, hydrogen bonding, phase-separation or other associations. Chemically crosslinked hydrogels on the other hand involves the reaction between functional groups present on polymer backbone with multifunctional crosslinking agents. Many of the hydrogels are product of schiff-base formation in which co-valent bond is involved. Co-polymerization of monomers and low molecular weight pre-polymers results into hydrogels formation. Ionic species and radiation takes active part in the initiation process of co-polymerization. Ceric ion and gamma radiation are the significant contributors in the catalysis process. This review article attempts to discuss naturally available biopolymer based hydrogels along with synthetically derived one and incorporates the findings from literature regarding methods of hydrogels preparation based on starting materials.
This review summarizes the synthesis methods for anionic polyacrylamide. The paper lists six different kinds of anionic polyacrylamide synthesis technologies, including homopolymerization posthydrolysis process, homopolymerization cohydrolysis process, copolymerization approach, inverse emulsion polymerization, precipitation polymerization and radiation polymerization. What's more, the authors discussed the application status of anionic polyacrylamide in water treatment. Based on these reviews, future research perspectives relating to its synthesis and application were proposed.
Gums are naturally occurring polysaccharides in plants, which are essentially cheap and abundantly available. The industrial demand of putative form of gums or their chemically modified derivatives has been increasing due to their safety, biodegradability, biocompatibility and nontoxicity. This is because these gums are acceptable as thickening agent, gelling agent, emulsifying agent, binding agent, encapsulating agent, swelling agent, disintegrating agent, foam stabilizer, etc. These gums can be modified in different ways to obtain tailor-made materials for drug delivery systems and thus can compete with the available synthetic excipients. In addition, the chemical modification of these gums further improves their physicochemical as well as mechanical properties. This chapter is aimed at discussing the modification of gums through derivatization of functional groups, graft ing with polymers, crosslinking with ions, etc., along with their uses in pharmaceutical drug delivery. Further, the factors influencing these processes in the pursuit of making them suitable for modifying the drug release properties of pharmaceutical dosage forms and for other purposes in pharmaceutical industry are also discussed.
The troublesome shale formations need special formulation of drilling fluids having high shale inhibition characteristics to mitigate wellbore instability problems. In the present study, polyacrylamide/clay na-nocomposite (PANC) was synthesized and used as drilling fluid additive. The free radical polymerization technique was adopted for the synthesis of the nanocomposite and it was characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and thermogravimetric analysis. During the synthesis, clay to monomer ratios were varied and the effect of synthesized product on the rheological and filtration properties of the drilling fluid system was studied thoroughly. Finally, most suitable grade of PANC was utilized as a drilling fluid additive and its effect on the shale recovery was studied and compared with partially hydrolyzed polyacrylamide, a frequently used shale en-capsulator. The experimental investigations revealed that PANC exhibited superior shale encapsulation property than partially hydrolyzed polyacrylamide (PHPA). Hence, synthesized nanocomposite may be used as a drilling fluid additive in inhibitive water based drilling fluid system.
Graft copolymerization of methacrylonitrile (MAN) onto carboxymethylcellulose (CMC) was carried out under argon atmosphere in a homogeneous aqueous medium by using ceric ammonium nitrate (CAN) as an initiator. The FTIR spectroscopy and solubility characteristics of the products were used for confirming the graft copolymer formation. The effect of the concentration of the initiator, monomer and polysaccharide as well as the reaction time and temperature on the graft copolymerization reactions were investigated to achieve the optimum grafting conditions (i.e. CAN 0.00065 mol/L, MAN 0.85 mol/L, CMC 1% W/V, reaction temperature 45°C, and reaction time 2 h). According to the empirical rates of the polymerization and the graft copolymerization of MAN onto CMC backbone, the overall activation energy of the graft copolymerization reaction was estimated to be 29.8 kJ/mol.
Thiol-derivatization of xanthan gum polysaccharide was carried out by esterification with mercaptopropionic acid and thioglycolic acid. Thiol-derivatization was confirmed by Fourier-transformed infra-red spectroscopy. Xanthan-mercaptopropionic acid conjugate and xanthan-thioglycolic acid conjugate were found to possess 432.68mM and 465.02mM of thiol groups as determined by Ellman's method respectively. Comparative evaluation of mucoadhesive property of metronidazole loaded buccal pellets of xanthan and thiolated xanthan gum using chicken buccal pouch membrane revealed higher ex vivo bioadhesion time of thiolated xanthan gum as compared to xanthan gum. Improved mucoadhesive property of thiolated xanthan gum over the xanthan gum can be attributed to the formation of disulfide bond between mucus and thiolated xanthan gum. In vitro release study conducted using phosphate buffer (pH 6.8) revealed a sustained release profile of metronidazole from thiolated xanthan pellets as compared to xanthan pellets. In conclusion, thiolation of xanthan improves its mucoadhesive property and sustained the release of metronidazole over a prolonged period.
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New methods of synthesis of graft copolymers using redox systems are discussed. In these the reducing agents are cellulose preparations containing thiocarbonate groups and the oxidizing agents are ions of metals of variable valency (V5+, Fe3+, Cr6+). An analysis is given of specific features of graft copolymerization conducted under heterogeneous conditions using the method of chain transfer from radicals formed by catalytic decomposition of hydrogen peroxide by Fe2+ ions bound to the cellulose. The problem of increasing the conversion of monomer by carrying out heterogeneous grafting by the method of chain transfer from initiator radicals is discussed. A new method is proposed and illustrated by examples, permitting grafting to be achieved with almost 100% conversion of monomer in some instances.
Polymerization of acrylonitrile in dilute aqueous solution initiated by the chloratesulfite redox was studied kinetically and with the aid of the electron microscope. Polymerization rate depended on the [ClO] [H2SO3] product, the monomer content and the sodium lauryl sulfate concentration. The rate was depressed by agitation and by salts; it was accelerated by Fe++ and by Cu++ and was only moderately dependent on temperature. Particles of polymer separated from the start as spheroids less than 200 A. across and grew rather uniformly to 2000 to 3000 A. After a short time no new particles formed unless more initiator was added. Rate of polymerization per particle was reasonably constant. Salts and agitation led to aggregation of particles and polymerization rate was reduced. Sodium lauryl sulfate and Methocel had the opposite effect. The system bears a general resemblance to typical emulsion polymerization, and thus treatments based on homogeneous kinetics appear to be inadequate.
Graft copolymers of carboxymethyl cellulose and starch with polyacrylamide have been synthesized by grafting acrylamide onto carboxymethyl cellulose and starch, respectively, using a ceric-ion-initiated solution polymerization technique. These graft copolymers have been tested for their drag-reduction effectiveness, shear stability, and biodegradability. It has been shown that grafting enhances the drag-reduction effectiveness and shear stability and also that these factors are very much dependent on the length and number of grafts in the molecule. None of the graft copolymer solutions shows any microbial degradation up to 10 days.
Guar gum based graft coplomers ¯occulation and rheo-logical behaviours Grafting onto cellulose. Effect of complexing agents on Fanta's reagent (Fe 12 /H 2 O 2 ) initiated grafting of poly(vinyl acetate)
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Kanan, K. (1998). Guar gum based graft coplomers ¯occulation and rheo-logical behaviours. MTech thesis, IIT, Khragpur, India. Mishra, B. N., Dogra, R., Kaur, I., & Jassal, J. K. (1979). Grafting onto cellulose. Effect of complexing agents on Fanta's reagent (Fe 12 /H 2 O 2 ) initiated grafting of poly(vinyl acetate). Journal of Polymer Science, Polymer Chemistry Edition, 17, 1861.
New redox systems in synthesis of cellulose graft copolymer
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Guar gum based graft coplomers flocculation and rheological behaviours
- K Kanan
Grafting onto cellulose. Effect of complexing agents on Fanta's reagent (Fe+2/H2O2) initiated grafting of poly(vinyl acetate)
- Mishra