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A) molecular structure and hydrogen bonding network of natural cellulose; (B) structure of cellulose after acetylation in EmimAc, the hydrogen bonding network was partially destroyed, the crystal structure was the combination of amorphous and the crystalline regions and lateral spaces between long molecular chains of cellulose was appeared; (C) hydrogen bonds between water molecular and hydroxyl groups of cellulose were formed and the hydrogen bonding network was completely destroyed; (D) CA sample was soluble in water.
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In the present study, we describe a novel one-step method to prepare water-soluble cellulose acetate (WSCA) with higher degree of polymerization values (DP = 650–680) by in situ activation of carboxyl group in ionic liquid. First of all, cellulose was dissolved in 1-ethyl-3-methylimidazolium acetate (EmimAc) and reacted with dichloroacetyl chloride...
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Sago waste is a potential source of cellulose but it has not been utilized properly. To improve the properties of cellulose based sago waste, it can be done by acetylation process. The objective of this research was to createcellulose acetate from sago waste with variation of acetic anhidride concentration. Microcrystalline cellulose could be prepa...
Citations
... However, the AcCFs samples that were prepared with the Ac-II and Ac-III systems were prone to decreasing yield with increasing DS. Cellulose acetates with DS values of 0.3-0.9 are water-soluble (Kamide et al. 1981(Kamide et al. , 1987Miyamoto et al. 1985;Iijima et al. 1992;Gomez-Bujedo et al. 2004;Cao et al. 2016;Pang et al. 2016). Thus, cellulose acetate molecules with low DS values in the AcCFs might have become increasingly water-soluble, resulting in decreased yield. ...
Quick drying after water or sweat absorption is an important function of underwear. In this study, the hydroxy groups of cotton knitted fabrics (CFs) were partially acetylated, maintaining the original fabric structure. The following three heterogeneous acetylation processes were used: Ac-I (Ac2O/H2SO4/toluene), Ac-II (Ac2O/H2SO4/AcOH/water), and Ac-III (Ac2O/AcONa) systems (Ac2O, acetic anhydride; AcOH, acetic acid; AcONa, sodium acetate). Acetylated cotton knitted fabrics (AcCFs) with degree of substitution (DS) ≤ 0.5 and yields of > 80% were prepared. AcCFs prepared with the Ac-III system gave high degree of polymerization (DP) values of > 1500, whereas those prepared with the Ac-II system exhibited low DP values of ≤ 400. The moisture contents of AcCFs at 20 °C and 65% relative humidity decreased from 7.1 to 4.7% with increasing DS value up to 0.46; introducing hydrophobic acetyl groups into the CFs decreased their hydrophilic nature. Quick drying similar to that of a polyester fabric was achieved for some of the AcCFs with DS values of < 0.2. When the acetyl groups in the AcCFs were homogeneously distributed across each fiber width (achieved for AcCFs prepared with the Ac-II system), quick drying was evident in the AcCFs. The crystallinities and crystal widths of cellulose I for the AcCFs with DS values of ≤ 0.28 were almost unchanged compared with those of the original CFs. However, neither the crystallinities nor crystal widths of cellulose I were directly related to quick drying after water absorption. Thermal degradation of the AcCFs varied between the acetylation systems, and depended on the DP values and/or the presence of sulfate ester groups in the AcCFs.
Graphical Abstract
... [21,22] The esterification of cellulose is among the most versatile technique for the introduction of organic functional groups on cellulose backbone to synthesize new materials basedcellulose. [23][24][25][26][27][28] The synthesis of cellulose benzoate with various degrees of substitution (DS), in an ionic liquid [Amim](Cl), 1butyl-3-methylimidazolium benzoate (BmimPhCOO), and CO 2 / DBU/DMSO, has been reported. [29][30][31] Cellulose benzoate is one of the potential derivatives of cellulose used for the separation of enantiomers by HPLC. ...
Cellulose p‐halide benzoates (C‐p‐HB) were synthesized by reacting microcrystalline cellulose (MCC) with p‐halide benzoyl chloride (p‐HBCl) namely; the p‐Iodobenzoyl chloride (p‐IBCl), p‐Bromobenzyl chloride (p‐BBCl), and p‐Nitrobenzoyl chloride( p‐NBCl) in ionic liquid 1‐butyl‐3‐methylimidazolium chloride [Bmim](Cl) at 60 °C for 2 h in the presence of 4‐dimethylaminopyridine (DMAP) as a base. The synthetic products were characterized through infrared spectrometry (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy, XRD, and scanning electron microscopy (SEM). Then, the effects of p‐halide benzoate groups on the thermal degradation of C‐p‐HB esters with DS≈1 were investigated using thermogravimetric analysis under an inert atmosphere from room temperature to 600 °C at a heating rate of 5 °C/min. The DSC analysis was used to determine the glass temperature and heat of the reaction of C‐p‐HB esters. The results indicated that the C‐p‐HB was successfully synthesized in [Bmim](Cl) with a DS≈1. The kinetic parameters were determined by the Coats‐Redfern (CR) method. The corresponding kinetic parameters of the main degradation stages were also determined. The thermal stability of MCC was remarkably decreased through esterification with p‐HBCl. The Criado method was used to determine the most probable degradation functions. Thus, reaction orders F2 and F3 were most probably the functions that describe the degradation of C‐p‐HB.
... The acetylation process, at the basis of the synthesis of cellulose acetate, imparts specific properties to the material, but it also makes it more resistant to dissolution and recycling (Zugenmaier, 2004). The DS plays a major role in the dissolution of CA: the solubility of CA in common organic solvents like acetone, chloroform, and dioxane is guaranteed only with DS in the range of 2-2.5 (Pang et al., 2016;Fischer et al., 2008). This may represent a potential limitation in the effectiveness of traditional recycling methods when the DS of CA waste is unknown. ...
Cellulose acetate (CA) is a versatile polymer with various industrial applications, but its recycling process is still
far from diffuse adoption. In this study, the purification of CA was confirmed through FTIR analysis, which
exhibited characteristic peaks corresponding to cellulose molecules and acetylation. The rheological behavior of
regenerated CA demonstrated shear thinning properties, making it suitable for applications requiring viscosity
reduction under shear. Oscillation strain and frequency sweep tests revealed the formation of a gel-like network
structure in CA solutions due to extensive hydrogen-bonding networks between water and acetone. The evaporation kinetics of acetone from CA films were found to be temperature and thickness-dependent, exhibiting both
Fickian and non-Fickian diffusion mechanisms. The diffusion coefficient of acetone in CA films was determined
and correlated with film porosity. Mechanical testing indicated comparable strain at rupture and ultimate
strength between recycled and commercial CA, while a limited reduction was observed for the elastic modulus.
These findings suggest potential applications of recycled CA in packaging and textile sectors, highlighting the
importance of further research in optimizing its properties for specific industry requirements.
... According to the literature results, ionic liquids combined with ammonium, pyridinium and imidazolium cations are able to dissolve cellulose (Table 3) [85][86][87][88]. Table 3. ...
Based on the environmental concerns, the utilisation of hemicelluloses in food packaging has become a sustainable alternative to synthetic polymers and an important method for the efficient utilisation of biomass resources. After cellulose, hemicellulose is a second component of agricultural and forestry biomass that is being taken advantage of given its abundant source, biodegradability, nontoxicity and good biocompatibility. However, due to its special molecular structure and physical and chemical characteristics, the mechanical and barrier properties of hemicellulose films and coatings are not sufficient for food packaging applications and modification for performance enhancement is needed. Even though there are many studies on improving the hydrophobic properties of hemicelluloses, most do not meet environmental requirements and the chemical modification of these biopolymers is still a challenge. The present review examines emerging and green alternatives to acetylation for xylan hemicellulose in order to improve its performance, especially when it is used as biopolymer in paper coatings or films for food packaging. Ionic liquids (ILs) and enzymatic modification are environmentally friendly methods used to obtain xylan derivatives with improved thermal and mechanical properties as well as hydrophobic performances that are very important for food packaging materials. Once these novel and green methodologies of hemicellulose modifications become well understood and with validated results, their production on an industrial scale could be implemented. This paper will extend the area of hemicellulose applications and lead to the implementation of a sustainable alternative to petroleum-based products that will decrease the environmental impact of packaging materials.
... Seemingly the side product formation depends on the acyl donor and in some cases, it can override the originally desired synthesis (Scheme 1a and b). 27,30,31 Another class of ILs, namely superbase ionic liquids (SB-ILs), could potentially be used as an alternative to the archetypical cellulose solvents and the imidazolium ILs. These ILs are composed from equimolar amounts of organic superbase (a compound which has very high affinity to protons) e.g., amidine or guanidine and carboxylic acid e.g., formic, acetic, propionic acid, etc. SB-ILs based on the bicyclic guanidine core are particularly attractive, because they have showed excellent capabilities for cellulose dissolution and they are already used in the manufacturing of regenerated cellulosic materials, like textile bres. ...
A sustainable homogeneous transesterification protocol utilizing the superbase ionic liquid [mTBNH][OAc] and unactivated methyl esters has been developed for the preparation of cellulose esters with controllable degree of substitution. [mTBNH][OAc] shows excellent recyclability with a high recovery of sufficient purity for repeated use. This reaction media allows for cellulose transesterification reactions not only using activated or cyclic esters, but also with unactivated methyl esters, which extends the substrate and application scope. Furthermore, the solubility properties of the prepared cellulose materials were tested and some intrinsic trends were observed at low degrees of substitution.
... This reaction was previously reported by Cohen et al [59]. that found that dichloromethane mixed with 1- for example, to use this system to dissolve cellulose and produce cellulose acetate [60]. However, in the case of IL recovery, this is undesirable, as there is the consumption of dichloromethane and the loss of the structure of IL, our target product for recovery. ...
Superbase-based ionic liquids 7-methyl-1,5,7-triazabicyclo-[4.4.0]dec-5-enium acetate, [mTBDH][OAc], and 5-methyl-1,5,7-triaza-bicyclo-[4.3.0]non-6-enium acetate, [mTBNH][OAc], are good candidates to produce high performance cellulose fibres while presenting much easy spinnability and good recyclability, than the state-of-the-art ionic liquids. Nevertheless, the recovery of the IL from the aqueous spinning bath and its purification, which are both an economical and environmental necessity, are important aspects that are still not solved. Aiming to gather knowledge to recover and recycle superbase-ILs, the main goal of this work is the physicochemical characterization of the binary systems water + [mTBDH][OAc] or [mTBNH][OAc]. Measurements performed include solid-liquid equilibria, vapor-liquid equilibria, water activity, Kamlet−Taft solvatochromic parameters, densities, and viscosities. An experimental screening on possible hydrophobic extractants for the recuperation of the ionic liquids from aqueous solution was performed. Using butanol, an extraction efficiency of 37% for [mTBDH][OAc] was achieved. Better extraction efficiencies were achieved with chlorinated solvents, however, they seem to react with the ILs anion.
... Recently, our group has developed a new one-step process for preparing water-soluble cellulose derivatives with a higher degree of polymerization values (DP = 650-680) by in situ acylation of cellulose in 1ethyl-3-methylimidazolium acetate (EmimAc) ionic liquid [30]. In this process, cellulose was dissolved in EmimAc ionic liquid to react with dichloroacetyl chloride (Cl 2 AcCl). ...
... Based on our recent findings [30], Cl 2 AcCl (0.7 mL) was added to 10 g ionic liquid dropwise under magnetic stir for 10 min at room temperature until the Cl 2 AcCl and the ionic liquid was mixed homogeneously to produce a mixed anhydride. Then, 0.3 g materials were dissolved in the aforementioned anhydride mixed solution under magnetic stir at 75°C. ...
... This consequently led to slow moisture absorption into the untreated films. 23 That is why formic acid-treated ACC film tends to absorb more moisture compared to the untreated composite films. ...
... Interestingly enough, this cellulose derivative could go both ways, either water-soluble or organosoluble depending on the degree of substitution (DS). At higher DS, CA is organosoluble [17] and it starts to exhibit good solubility in water at lower DS (0.4-1.2) [18,19]. Several methods have been proposed to synthesize CA in which the standard approach is always accompanied with the formation of acidic reagents since it involves the use of acetic acid and acetic anhydride in the presence of strong acids such as sulphuric acid as catalyst [2,17]. ...
... The third peak appearing at 2.50 ppm corresponds to the protons from DMSO-d6 solvent and lastly, the peaks appearing at 1.60-2.30 ppm belong to the three methyl protons of acetate group [18] which further confirm the successful substitution of acetyl groups from vinyl acetate onto the cellulose backbone. The spectra for the other CA powders showed similar characteristic peaks as CA-1:15 sample. ...
Cellulose is widely appreciated amongst polymer scientists as the most abundant and cost-effective natural polysaccharide. Nonetheless, the non-dissolving property of cellulose has narrowed its potential from a broader range of applications. Hence, modification has to be made in order to improve its solubility. In this study, a simple, robust and rapid transesterification method using vinyl acetate was carried out by acetylating microcrystalline cellulose (MCC) to obtain cellulose acetate (CA). The solubility test showed an improvement of organosolubility for the modified cellulose. Series of CA powders at five different degrees of substitution (DS) were prepared by varying the composition of cellulose to vinyl acetate molar ratios. Successful acetylation of cellulose was confirmed through Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopies. Physicochemical traits were studied by using X-ray diffraction (XRD) and thermogravimetric analysis (TGA). XRD and TGA measurements revealed that CA powders of different DS were less crystalline and more thermally stable than its native form. The CA powders were turned into quasi-solid polymer electrolytes (PEs) and the highest ionic conductivity reported in this study was 7.31 × 10−3 S cm−1 with incorporation of 20 wt.% sodium iodide (NaI) salt. Rheology study was carried out to investigate the mechanical strength of the gels. Quasi-solid PEs were prepared for potential dye-sensitized solar cells (DSSCs) application.
... In this study, cellulose has been chosen as a promising precursor material for the fabrication of drug nanocarriers as it is renewable, biodegradable and low in toxicity [3]. ...
In this study, pH responsive carboxylic cellulose acetate nanoparticles (CCA NPs) have been evaluated as drug nanocarriers for controlled release of drug. Herein, carboxylic cellulose acetate (CCA) was initially synthesized via oxidation of cellulose using a 2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO) as an oxidant and followed by the acetylation of carboxylic cellulose in the presence of iodine as a catalyst. CCA NPs were then obtained via the nanoprecipitation process and subsequent sonication. The obtained CCA NPs with a mean diameter of 96 nm were subsequently evaluated as drug delivery nanocarriers. Penicillin G as a model drug was loaded onto the CCA NPs via the adsorption process. Drug release profiles of Penicillin G from CCA NPs were evaluated in phosphate buffer solution (PBS) at different medium pH values (1.2, 7.4, and 8.6). Release kinetic models were applied to determine the release mechanism of penicillin G from loaded CCA NPs. Results showed that pH-responsive release of penicillin G from CCA NPs which was released most slowly at medium of pH 7.4.
