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Schematic of fumed silica particles modification with dilute polymer solution of dimethysiloxane chains or silylation with trichloro(octadecyl)silane.
Source publication
Silica nanomaterials modified with monomolecular C18-alkyl silane or oligomeric dimethylsiloxane units were loaded in-situ during the formation of PDMS membrane. The small-angle neutron scattering (SANS) study was performed to probe structural compatibility between the modified silica and PDMS. The Ornstein-Zernike (OZ) and Debye-Anderson-Brumberge...
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... the fumed silica after dispersion in toluene solvent by ultra-sonication for half an hour was silylated by reaction with trichloro(octadecyl)silane at 60 °C for 3 h. The molar mass ratio of the fumed silica to the tri- chloro(octadecyl)silane was 10:1. The above modification processes of the fumed silica are schematically shown in Fig. ...
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... contact angle (CA) measurement was carried out to check the hydrophobic nature of the sample surfaces. As shown in Fig. 10, the fumed silica nanoparticles showed water CA < 10° whereas the surface modified silica Types (1S, 2S and 3S) exhibited the water CA values 149-152°. All the silica filled PDMS samples showed higher water CA values 133-152° than the virgin PDMS of 109° water CA value as shown A.M. Kansara et al. Polymer 160 (2019) 30-42 in Fig. 11. ...
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... As shown in Fig. 10, the fumed silica nanoparticles showed water CA < 10° whereas the surface modified silica Types (1S, 2S and 3S) exhibited the water CA values 149-152°. All the silica filled PDMS samples showed higher water CA values 133-152° than the virgin PDMS of 109° water CA value as shown A.M. Kansara et al. Polymer 160 (2019) 30-42 in Fig. 11. The value of water contact angle (CA) for the composite sample was increased with increase in the amount of silica loading. On the other hand, the ethanol and butanol CA values were found to be decreased from ∼42° to 12° with increase of silica loading in the PDMS indicating more organophilic nature with higher silica loading. Using ...
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... of water contact angle (CA) for the composite sample was increased with increase in the amount of silica loading. On the other hand, the ethanol and butanol CA values were found to be decreased from ∼42° to 12° with increase of silica loading in the PDMS indicating more organophilic nature with higher silica loading. Using AFM images shown in Fig. 12, the surface roughness of the membranes 1S-10, 2S-10 and 3S-10 of low silica content (10& #x202F;wt. %) is compared with the membranes 1S-10, 2S-30 and 3S- 30 of higher silica content (30 wt. %). The data obtained from the analysis of the AFM images are given in Table 3. It was observed that the value of average roughness (S a ) ...
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... of silica loading in the membrane for pervaporation separa- tion performance was studied. Fig. 13 shows the performance of 1S type silica-PDMS membrane series with variation in silica loading of 5, 10, 20 and 30 wt. %. The feed solution was 5 wt. % ethanol in water or and 3 wt. % butanol in water. As expected, the permeate fluxes were found to be increased for the membrane with increase in silica loading since ...
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... than ethanol through the hydro- phobic membrane. So, the flux and separation factor of butanol/water for the membranes were found to be higher than the case of ethanol/ water separation. The performances of other 2S-PDMS and 3S-PDMS membrane series in pervaporation separation of ethanol-water and butanol-water solu- tions were also studied. Fig. 14 shows comparison of the membranes in terms of the flux and separation factor. The 3S-30 membrane showed the best performance with in terms of flux and alcohol/water separation factor. In case of the 1S membrane series, the alcohol/water separation factor was the maximum for the 1S-20 while it was the 2S-10 among the 2S membrane series. ...
Citations
... This rinsing procedure was carried out to remove the produced HCl and unreacted FDTS resulting from the chemical grafting reaction between silica particles and FDTS. Following the rinsing steps, the SRS particles were re-suspended in 0.1 g of hexane [36]. ...
The growing prevalence of antimicrobial resistance in bacterial strains has increased the demand for preventing biological deterioration on the surfaces of films used in applications involving food contact materials (FCMs). Herein, we prepared superhydrophobic film surfaces using a casting process that involved the combination of low-density polyethylene (LDPE) with solutions containing surface energy-reducing silica (SRS). The bacterial antifouling properties of the modified film surfaces were evaluated using Escherichia coli O157:H7 and Staphylococcus epidermidis via the dip-inoculation technique. The reduction in bacterial populations on the LDPE film embedded with SRS was confirmed to be more than 2 log-units, which equates to over 99%, when compared to the bare LDPE film. Additionally, the modified film demonstrated liquid-repelling properties against food-related contaminants, such as blood, beverages, and sauces. Moreover, the modified film demonstrated enhanced durability and robustness compared to one of the prevalent industry methods, dip-coating. We anticipate that the developed LDPE/nano-silica composite film represents a promising advancement in the multidisciplinary aspects of food hygiene and safety within the food industry, particularly concerning FCMs.
... As a result of its excellent thermal and chemical stability, and convenient membrane formation, polyvinylidene fluoride (PVDF) is widely considered as one of the most promising environmentally friendly membrane materials [1][2][3]. PVDF membranes have been extensively applied to the discharge and reuse of domestic sewage and industrial wastewater [4,5]. However, the intrinsic hydrophobic property of PVDF materials and low surface energy both depress the water permeability and anti-fouling ability of the resulting membranes [6,7]. ...
Aiming at enhancing on the permeation and anti-fouling performance of polyvinylidene fluoride (PVDF) membranes, hydrophilic polymers containing AgCl nanoparticles prepared via in-situ microemulsion polymerization were blended with PVDF polymer. Firstly, AgCl nanoparticles generated in the reverse microemulsion using a mixture of styrene and methyl methacrylate as an oil phase. Subsequently, the polymerized microemulsion with AgCl nanoparticles generated from the reverse microemulsion through in-situ polymerization for the oil phase. Finally, PVDF blending membranes were constructed by blending polymerized microemulsion with PVDF. From the results by the structural characterization and ultrafiltration experiments, it was found that addition of the polymerized microemulsion containing hydrophilic polymers and AgCl nanoparticles both improved the pore structures and hydrophilicity of the blending membranes, thus enhancing their permeation performance and anti-fouling property. However, excess polymerized microemulsion could not blend uniformly with PVDF and caused the formation of AgCl agglomerates in the blending membranes, which depressed both permeation performance and anti-fouling property of the resulting membrane.
Bioethanol, as a clean and renewable fuel, has gained increasing attention due to its major environmental benefits. Pervaporation (PV) is a promising and competitive technique for the recovery of ethanol from bioethanol fermentation systems due to the advantages of environmental friendliness, low energy consumption and easy coupling with fermentation process. The main challenge for the industrial application of ethanol perm-selective membranes is to break the trade-off effect between permeability and selectivity. As membrane is the heart of the pervaporation separation process, this article attempts to provide a comprehensive survey on the breakthroughs of ethanol perm-selective PV membranes from the perspectives of tailoring membrane materials to enhance PV separation performance. The research and development of polymeric and organic/inorganic hybrid membranes are reviewed to explore the fundamental structure-property-performance relationships. It is found that mixed matrix membranes with well-designed membrane structures offer the hope of better control overphysi-/chemical micro-environment and cavity/pore size as well as size distribution, which may provide both high permeability and membrane selectivity to break the trade-off effect. The tentative perspective on the possible future directions of ethanol perm-selective membranes is also briefly discussed, which may provide some insights in developing a new generation of high-performance PV membranes for ethanol recovery.
Three-dimensionally (3D) structured soft electronic devices that fit the contour of target organs or tissues are preferred for the stable implantation of biomedical devices. However, the metal patterns deposited on soft materials, especially polydimethylsiloxane (PDMS), can generate microcracks or disconnections following an expansion of the substrate. A way to generate 3D structured soft devices is using fluid injection into the unbonded area of a selectively bonded 2D structure comprised of PDMS and parylene layers. This work outlines the development of 3D soft bioelectronic devices, including the fabrication processes optimized for stable metal patterns even after substrate expansion via fluid injection. The generation of cracks in metal patterns was significantly affected by the sputtered material for plasma mask during the selective bonding process and the thickness of the intermediate parylene layer used underneath the sputtered metal. An RF-sputtered titanium mask was chosen to create crack-free metal patterns on the intermediate parylene layer based on PDMS substrate. Moreover, the thickness of the intermediate parylene layer was optimized using finite element analysis for stable and intact metal patterns after fluid injection. The developed soft bioelectronic device successfully demonstrated the ability to record and stimulate the peripheral nerve in vivo as cuff electrodes. The optimized processes developed in this study not only enable soft 3D electronic devices applicable to internal organs or tissues with 3D curvatures, but also suggest a promising way to fabricate flexible electronics using conventional micromachining processes such as photolithography and metal sputtering on soft and expandable substrates.
Pervaporation separation of acetone-butanol-ethanol aqueous mixture was studied to recover butanol. Polyphenylsulfone supported polydimethylsiloxane coated membranes were developed with polyvinylpyrrolidone additive and with two fumed silica fillers; Aerosil R202, treated with polydimethylsiloxane and Aerosil R972, treated with dimethyldichlorosilane. Membranes were prepared with fillers in each layer of the membrane, in both layers and without any filler, to investigate the effect of the fillers on the membrane performance. Furthermore, the effect of the thickness of each membrane layer was investigated. An increase in PDMS layer thickness promotes separation factor and suppresses flux, while an increase in the PPSU layer thickness has an inverse effect. After pervaporation tests at various operating conditions, the best PV performance was achieved with the membranes including R972 particles in the support layer. In the concentration range of 2-5% BuOH of feed, the average separation factor increased from 7.6 to 30.6, and the average flux increased from 300 to 536 g.m⁻² h⁻¹ by the incorporation of 3% R972 silica in the support layer. The partial fluxes of the solvents obtained from PV tests followed the order: butanol > water > acetone > ethanol. The developed R972 silica filled PPSU/PDMS membranes are found to be promising for butanol recovery from binary and quaternary aqueous mixtures.
