Structure/property relationship of polyvinyl alcohol/dimethoxydimethylsilane composite membrane: Experimental and theoretical studies

Effect of Polyethylene Glycol Methyl Ether Methacrylate on the Biodegradability of Polyvinyl Alcohol/Starch Blend Films

Blend copolymers (PVA/S) were grafted with polyethylene glycol methyl methacrylate (PEGMA) with different ratios. Potassium persulfate was used as an initiator. The blend copolymer (PVA/S) was created by combining poly(vinyl alcohol) (PVA) with starch (S) in various ratios. The main idea was to study the effect of different ratios of the used raw materials on the biodegradability of plastic films. The resulting polymers (PVA/S/PEGMA) were analyzed using FTIR spectroscopy to investigate the hydrogen bond interaction between PVA, S, and PEGMA in the mixtures. TGA and SEM analyses were used to characterize the polymers (PVA/S/AA). The biodegradability and mechanical properties of the PVA/S/PEGMA blend films were evaluated. The findings revealed that the mechanical properties of the blend films are highly influenced by PEGMA. The time of degradation of the films immersed in soil and Coca-Cola increases as the contents of PVA and S and the molecular weight (MW) of PEGMA increase in the terpolymer. The M8 sample (PVA/S/PEGMA in the ratio of 3:1:2, respectively) with a MW of 950 g/mol produced the lowest elongation at break (67.5%), whereas M1 (PVA/S/PEGMA in the ratio of 1:1:1, respectively) with a MW of 300 g/mol produced the most (150%). The film's tensile strength and elongation at break were improved by grafting PEGMA onto the blending polymer (PAV-b-S). Tg and Tm increased when the PEGMA MW increased from 300 to 950. Tg (48.4 °C) and Tm (190.9 °C) were the lowest in M1 (300), while Tg (84.8 °C) and Tm (190.9 °C) were greatest in M1 (950) at 209.3 °C. The increased chain and molecular weight of PEGMA account for the increase in Tg and Tm of the copolymers.

Synthesis and Characterization of Nylon 6,6-Polyvinyl Alcohol-Based Polyelectrolytic Membrane

This work presents the preparation and investigation of blended nylon (N)/polyvinyl alcohol (PVA)-based polyelectrolytic membranes that are modified with different concentrations of sulfuric acid (SA), chlorosulfonic acid (CSA), and sulfonated activated carbon (SAC) as a filler. Scanning electron microscopy (SEM) micrographs illustrated good membrane homogeneity, and no cracks or phase separation were detected. Chemical interaction between N, PVA, and other membrane components was confirmed by Raman scattering spectroscopy and Fourier transform infrared (FTIR). In addition, the molecular structure is verified by energy depressive X-ray (EDX). Furthermore, water and methanol uptake, gel fraction, and IEC were determined as functions of varied membrane modification components. The results revealed that increasing the portion of SA, CSA and SAC led to an increase in IEC and ionic conductivity values reached 2.12 meq/g–0.076 S/cm for (N/PVA-4.0% SA-4.0% SAC), respectively, and 2.71 meq/g–0.087 S/cm for (N/PVA-4.0% CSA-4.0% SAC), respectively, while the IEC and ionic conductivity value for non-modified N/PVA membrane was 0.02 meq/g and zero, respectively. Such results enhance the potential feasibility of modified N/PVA electrolytic membranes for fuel cell (FC) applications.

Comparative Studies of the Dielectric Properties of Polyester Imide Composite Membranes Containing Hydrophilic and Hydrophobic Mesoporous Silica Particles

In this paper, comparative studies of hydrophilic and hydrophobic mesoporous silica particles (MSPs) on the dielectric properties of their derivative polyester imide (PEI) composite membranes were investigated. A series of hydrophilic and hydrophobic MSPs were synthesized with the base-catalyzed sol-gel process of TEOS, MTMS, and APTES at a distinctive feeding ratio with a non-surfactant template of D-(-)-Fructose as the pore-forming agent. Subsequently, the MSPs were blended with the diamine of APAB, followed by introducing the dianhydride of TAHQ with mechanical stirring for 24 h. The obtained viscous solution was subsequently coated onto a copper foil, 36 μm in thickness, followed by performing thermal imidization at specifically programmed heating. The dielectric constant of the prepared membranes was found to show an obvious trend: PEI containing hydrophilic MSPs > PEI > PEI containing hydrophobic MSPs. Moreover, the higher the loading of hydrophilic MSPs, the higher the value of the dielectric constant and loss tangent. On the contrary, the higher the loading of hydrophobic MSPs, the lower the value of the dielectric constant with an almost unchanged loss tangent.

Fabrication and optimization of electrospun polymeric nanofibers loaded with 5-fluorouracil and rosemary extract

BACKGROUND

Topical 5-fluorouracil [5FU] is one of the mostly prescribed medications for different types of skin cancer; however, it is associated with drug resistance and adverse effects. Rosemary extract has promising dose-dependent antitumor effects, as well as a synergistic effect in combination with 5-fluorouracil besides sensitizing the 5-FU-resistant cells.

OBJECTIVE

Polymeric nanofibers loaded with 5FU and rosemary extract were optimized to combine both ingredients in one controlled release drug delivery system, aiming to enhance the efficacy while retaining the adverse effects.

METHOD

Polymeric nanofibers loaded with 5-FU and rosemary were fabricated via electrospinning technique. Design expert software was utilized to study the effect of independent variables including polymer concentration, voltage, and feeding rate on the characteristics of the resulting nanofibers. Afterwards, the FTIR spectrum and release kinetic of the drug and extract from the optimized nanofibers and their cytotoxic effect against A375 cell line were investigated.

RESULTS

The formulation composed of 6.65% PVA electrospun at 1 mL.h-1 and 17.5kV was chosen as the optimum fabrication condition. The mean diameter of the optimized nanofibers was 755 nm. The drug and rosemary extract contents were 75.38 and 93.42%, respectively. The fabrication yield was 100%, bioadhesion force was 1.28 N, and bead abundance was 10 per field. The cytotoxicity of the optimized formulation was significantly higher than the control groups.

CONCLUSION

According to the appropriate loading percent, release efficiency and release kinetics, bioadhesion force, and cytotoxicity, these nanofibers could be further investigated as a topical treatment option to increase the efficacy of 5-FU.

Blend polyethersulfone/zirconium oxychloride octahydrate membranes crosslinked by polyvinyl alcohol layer for high saline water desalination

Mixed matrix membranes were prepared by blending polyethersulfone with zirconium oxychloride octahydrate (ZOH) solution, and coating by polyvinyl alcohol layer. Different analyses were applied in the prepared membranes. Membranes performances were examined using different salty solutions concentrations (5000, 10,000 and 20,000 mg/L) and a real sample from highly concentrated seawater (brine) of 1,30,900 mg/L. The results indicate that blending polyethersulfone with 1.5% ZOH and coating with polyvinyl alcohol (PVA) cross-linking layer (M4) provides salt rejection of 99.9% with permeate flux of 32.4 L/m2.h for the salt solution of 5000 mg/L, while salt rejection was 92% with permeate flux of 11.1 L/m2.h for the salt solution of 1,30,900 mg/L. The results indicate enhancement in the hydrophilicity of the membranes especially after coating by the PVA layer and increasing the ZOH%, such as the high permeate flux and the lowest contact angle of prepared membrane M4 (1.5% ZOH) which was 39.7°. A long time experiment was applied on the prepared membrane (M4), where the results indicate that the permeate flux for a long time was approximately fixed for 120 h, which indicates that the membrane can be considered as a self-cleaning membrane.