Preparation and characterization of poly(vinyl chloride)‐graft‐acrylic acid membrane by electron beam

Poly(vinyl chloride) (PVC) was irradiated by electron beam in vacuum at 20 KGy to produce living free radicals, and then reacted with acrylic acid (AA) in solution to obtain the PVC‐g‐AA copolymers. The copolymers were characterized by Fourier transform infrared spectroscopy. Porous membranes were prepared from copolymers by the phase inversion technique. The morphology of PVC‐g‐AA membranes was studied by field emission scanning electron microscopy. The mean pore size and pore size distribution were determined by a mercury porosimeter. The mean pore size was 0.19 μm, and the bulk porosity was 56.02%. The apparent static water contact angle was 89.0°. The water drop penetration rate was 2.35 times to the original membrane. The maximum stress was 4.10 MPa. Filtration experiments were carried out to evaluate the fouling resistance of the PVC‐g‐AA membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Improvement of filtration performance of polyvinyl chloride/cellulose acetate blend membrane via acid hydrolysis

Based on the hydrophilicity and biodegradability of cellulose acetate (CA), polyvinyl chloride (PVC)/CA blend membrane was prepared by solution comixing and phase transformation method. Then the CA in the blend membrane was partially hydrolyzed under acidic conditions to improve the hydrophilicity of the blend membrane, so as to improve the filtration performance of the PVC/CA blend membrane. The properties of the membranes were systematically characterized by Fourier transform infrared spectroscopy, differential scanning calorimeter, and scanning electron microscopy (SEM). The porosity, water contact angle, pure water flux (PWF), protein retention rate, and mechanical properties of the membrane were measured, and the effect of hydrolysis on the filtration performance of the blend membrane was analyzed. The results showed that the hydrophilicity and porosity of the blend membrane increased, the PWF and protein rejection rate enhanced after acid catalyzed hydrolysis, while the mechanical properties of PVC membrane were maintained. This simple preparation method endows PVC/CA blend membrane with desirable filtration performance, and also helps to overcome the disadvantages of poor hydrophilicity and easy pollution of pure PVC membrane.     

Enhanced glycerol dehydration of pervaporation cross-linked PVA membranes modified by VUV/UV-C treatments

The high glycerol miscibility in water needs more efficient processes to decrease the cost of dehydration. Water stable poly(vinyl alcohol) based membranes cross-linked with 15% w/w of maleic acid were used for dehydrating glycerol-water mixtures using pervaporation (PV). The membranes were characterized using water contact angle, profilometry, Fourier transformed infrared spectroscopy-attenuated total reflectance, x-ray photoelectron spectroscopy, water stability, swelling tests, and PV. Membranes were treated using dry methods with vacuum ultraviolet (VUV; 162 nm) or ultraviolet (UV)-C (254 nm) radiation and exposed to O₂ or acrylic acid vapors, respectively. The VUV and UV-C treatments improve PV performances, increasing the water separation selectivity more than 4 and 8.5 times, respectively. UV-C treatments exhibit a water flux (kg m⁻² h⁻¹), selectivity and PSI (kg m⁻² h⁻¹) of 0.3, 250, and 87.4 respectively. Highly hydrophilic functional groups grafted onto the surface of the membranes after irradiation favor the selective transfer of water through the membrane. Overall, the VUV or UV-C membrane treatments show great PV prospect in glycerol dehydration.     

Enhanced selective adsorption of cation organic dyes on polyvinyl alcohol/agar/maltodextrin water-resistance biomembrane

In this study, we designed a novel hydrogel composite membrane based on the combination of polyvinyl alcohol (PVA), agar, and maltodextrin through a facile solution-casting router. From Fourier-transform infrared spectroscopy, contact angle, scanning electron microscopy, and swelling analyses, the formation of hydrogen bonds between surface functional groups of PVA, agar, and maltodextrin was confirmed. As a result, the PVA/agar/maltodextrin membranes exhibited a more hydrophobic nature compared with pure PVA. The thermal stability and integrity of such obtained composite membranes were also elucidated by the evaluation of thermogravimetric analysis and mechanical behavior. Besides, the composite membrane exhibited high selective adsorption for cationic dyes, namely 20.2 mg g⁻¹ for methylene blue and 19.17 mg g⁻¹ for crystal violet at initial dye concentration of 100 mg/L, an adsorbent dosage of 0.1 g, contact time of 180 min, and solution pH 7, while anionic dyes such as congo red and methyl orange are approximately zero. The adsorption kinetics and isotherm of the as-prepared composite membranes were well fitted to the pseudo-second-order and Temkin model. The effect of factors, including contact time, solution pH, PVA content, and initial dye concentration on the adsorption capacity of the as-prepared composite membrane was also investigated in detail. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48904.     

Polypropylene/polypropylene‐grafted acrylic acid copolymer/ethylene–Acrylic acid copolymer ternary blends for hydrophilic polypropylene

Ternary blends of polypropylene (PP), a polypropylene‐grafted acrylic acid copolymer (PP‐g‐AA), and an ethylene–acrylic acid copolymer (EAA) were prepared by melt blending. The surfaces of films with different contents of these three components were characterized with contact‐angle measurements. Scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the microstructure, melting and crystalline behavior, and thermal stability of the blends. The contact angles of the PP/PP‐g‐AA blends decreased monotonically with increasing PP‐g‐AA content. With the incorporation of EAA, the contact angles of the PP/PP‐g‐AA/EAA ternary blends decreased with increasing EAA content. When the concentration of EAA was higher than 15 wt %, the contact angles of the ternary blends began to increase. Scanning electron microscopy observations confirmed that PP‐g‐AA acted as a compatibilizer and improved the compatibility between PP and EAA in the ternary blends. Differential scanning calorimetry analysis suggested that acrylic acid moieties could act as nucleating agents for PP in the polymer blends. Thermogravimetric analysis and differential thermogravimetry confirmed the optimal blend ratio for the PP/PP‐g‐AA/EAA ternary blends was 70/15/15. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 436–442, 2006     

Low molecular weight polyacrylic acid with pendant aminomethylene phosphonic acid groups

Low molecular weight poly(acrylic acid‐co‐vinyl aminomethylene phosphonic acid)s were prepared by consecutively applying the Hofmann degradation and the Mannich reaction to polyacrylamide and poly(acrylamide‐co‐acrylic acid)s. ¹H‐NMR, ³¹P‐NMR, and microanalysis were used for structural analyses. These polymers were tested as anti‐scalent and they showed better anti‐scalent effect than commercial poly(acrylic acid)s. The scale inhibition properties of copolymers increased with increasing amount of aminomethylene phosphonic acid groups. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 870–874, 2000     

Protein‐grafted carboxylic poly(ether sulfone) membranes: Preparation and characterization

Carboxylic poly(ether sulfone) membranes were prepared by a controlled acetylating and surface‐oxidating reaction followed by the grafting of bovine serum albumin (BSA) and bovine serum fibrinogen (BFG) onto the surfaces. Attenuated total reflection–Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and Micro BCA Protein Assay Kits confirmed that the proteins were successfully grafted onto the surfaces of the membranes. The protein grafting degrees were measured at different time intervals and under different conditions. The modified membranes showed higher hydrophilicity, lower protein (BSA and BFG) adsorption, and suppressed platelet adhesion values. Because of the binding of calcium ions in blood, the modified membranes showed longer plasma recalcification times, activated partial thromboplastin times, prothrombin times, and whole blood clotting times. The results indicate that the blood compatibility of the poly (ether sulfone) membranes could be improved after surface carboxylic modification and protein immobilization and that the modified membranes could be used in the blood purification field. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Swelling and Thermal Characteristics of Genipin Crosslinked Chitosan and Poly(vinyl pyrrolidone) Hydrogels

Summary Chitosan / poly(vinyl pyrrolidone) (PVP) were used to prepare semi-interpenetrating polymeric networks. The hydrogels were crosslinked using genipin, a non-toxic cross-linking agent extracted from the fruits of Gardenia jasminoides Ellis. Swelling properties of these hydrogels were studied in media of different pHs and temperatures. States of water in the swollen hydrogels at 25°C and pH 7 were determined using Differential Scanning Calorimetry (DSC). The swelling behaviour of the hydrogels was found to be dependent on the temperature and the pH of the swelling medium. The total water content in the hydrogels was found to increase with increasing PVP content.     

Preparation of chlorinated poly(vinyl chloride)‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membranes and their water permeation properties

Chlorinated poly(vinyl chloride) (CPVC) membranes for microfiltration processes were prepared with the combined process of a solvent evaporation technique and the water‐vapor induced‐phase‐inversion method. CPVC membranes with a mean pore size of 0.7 μm were very hydrophobic. These membranes were subjected to surface modification by ultraviolet (UV)‐assisted graft polymerization with N‐vinyl‐2‐pyrrolidinone (NVP) to increase their surface wettability and decrease their adsorptive fouling. The grafting yields of the modified membranes were controlled by alteration of UV irradiation time and NVP monomer concentration. The changes in chemical structure between the CPVC membrane and the CPVC‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membrane and the variation of the topologies of the modified PVC membranes were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and field emission scanning electron microscopy. According to the results, the graft yield of the modified CPVC membrane reached a maximum at 5 min of UV exposure time and 20 vol % NVP concentration. The filtration behavior of these membranes was investigated with deionized water by a crossflow filtration measurement. The surface hydrophilicity and roughness were easily changed by the grafting of NVP on the surface of the CPVC membrane through a simultaneous irradiation grafting method by UV irradiation. To confirm the effect of grafting for filtration, we compared the unmodified and modified CPVC membranes with respect to their deionized water permeation by using crossflow filtration methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3188–3195, 2003     

Preparation of hydrophilic polysulfone porous membrane by use of amphiphilic cellulose

A cellulose‐based amphiphilic co‐polymer with grafted myristyl groups was synthesized and used as an additive to modify polysulfone (PSf) membranes. Fourier transform infrared (FTIR) spectroscopy and Solid‐state cross polarization magic angle spinning carbon‐13 nuclear magnetic resonance (CP/MAS ¹³C NMR) spectroscopy were used to characterize the structure of the synthesized amphiphilic cellulose. The good compatibility between amphiphilic co‐polymer and PSf was confirmed by differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) was conducted to inspect morphology of the membrane. Furthermore, Thermal performance was indicated by thermogravimetric analysis (TGA). Contact angle, flux and retention behavior were also measured in this work. The structural similarity enhanced compatibility among components by introducing flexible alkyl groups. According to the findings obtained from characterization, better compatibility of cellulose with PSf was achieved after amphiphilic treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41664.     

Antifouling ultrafiltration membrane fabricated from poly (arylene ether ketone) bearing hydrophilic hydroxyl groups

A new kind of membrane formation polymer, cardo poly(arylene ether ketone) bearing hydrophilic hydroxyl groups (PEK‐OH) was synthesized from the biphenol monomer 2‐(2‐hydroxyethyl)‐3, 3‐bis (4‐hydroxyphenyl)‐isoindolin‐1‐one (PPH‐OH), and 4, 4′‐difluorodiphenylketone. PEK‐OH asymmetric ultrafiltration membranes were prepared using the immersion coagulation phase inversion method. The PEK‐OH membrane prepared using the optimized conditions exhibited a pure water flux of 516 ± 18 L·m^?2·h^?1 and a 99.1 ± 1.4% rejection of bovine serum albumin (BSA) at an operating pressure of 0.1 MPa. The contact angle of PEK‐OH membrane was 66.0 ± 2.4 lower than these of the PEK‐C membrane (87.0 ± 2.8°, prepared from polymer PEK‐C under the same membrane formation condition as PEK‐OH membrane) and the UE50 membrane (84.0 ± 1.6°, a commercial PES ultrafiltration membrane). The amount of BSA protein adsorbed to the PEK‐OH membrane under static condition was measured to be 3.12 μg·cm^?2, which was greatly lower than that of 88.71 μg·cm^?2 and 74.40 μg·cm^?2 for the PEK‐C and the UE50 ultrafiltration membranes, respectively. Under dynamic filtration of BSA experiments, the PEK‐OH ultrafiltration membrane showed a 78.3% water flux recovery ratio, while only a 39.7% for the PEK‐C membrane and 46.5% for UE50 membrane were detected in the first cycle. After three cycles of BSA and LYZ filtration, the flux recovery ratio of PEK‐OH ultrafiltration membrane changed to be stable at 75% and 73%, while that of PEK‐C and UE50 ultrafiltration membranes remained declining gradually. Thus, hydrophilic PEK‐OH improves antifouling membrane property. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42809.     

Preparation of poly(vinyl chloride) (PVC) ultrafiltration membranes from PVC/additive/solvent and application of UF membranes as substrate for fabrication of reverse osmosis membranes

Ultrafiltration (UF) membranes were prepared from poly(vinyl chloride) (PVC) as main polymer, poly(vinyl pyrrolidone) (PVP) as additive, and 1‐methyl‐2‐pyrrolidone (NMP) as solvent using Design Expert software for designing the experiments. The membranes were characterized by SEM, contact angle measurement, and atomic force microscopy. The performance of UF membranes was evaluated by pure water flux (PWF) and blue indigo dye particle rejection. In addition, the molecular weight cutoff of UF membranes was determined by poly(ethylene glycol) (PEG) rejection. The UF membranes were used as substrates for fabrication of polyamide thin film composite (TFC) reverse osmosis (RO) membranes. The results showed that the model had high reliability for prediction of PWF of UF membranes. Also, increment in PVC concentration caused reduction of PWF. Moreover, at constant PVC concentration and if the concentrations of PVC was lower than 10 wt %, the PWF reduced by increasing the concentration of PVP. However, at PVC concentration higher than 11 wt %, increment in PVP concentration showed increment and reduction of PWF. The PEG rejection results showed that the prepared membranes had UF membranes properties. Finally, the NaCl rejection tests of RO membranes by PVC as substrates indicated that the performance of RO membranes were lower than commercial membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46267.     

Preparation and characterization of nano‐CaCO3 encapsulated with polyacrylic and its application in PVC toughness

The properties and morphology of nano‐calcium carbonate (nano‐CaCO₃) modified with the titanate coupling agent isopropyl trioleoyl titanate (IPTT) were characterized by Fourier transform infrared, thermogravimetric analyses, surface tension, and transmission electron microscopy. The results showed that the grafting ratio of IPTT on the surface of nano‐CaCO₃ (IPTT‐Ca) increased with IPTT content. IPTT‐Ca/PBA/PMMA (IPTT‐Ca/ACR, PBA/PMMA core‐shell polymer, referred to ACR) latexes were prepared by seeded emulsion polymerization. They were then used to mix with PVC resin. The outer layer (PMMA) enhanced the dispensability of IPTT‐Ca/ACR in the PVC matrix by increasing the interfacial interaction of these composite particles with PVC. The notched impact strengths of the blends were influenced by the weight ratio of IPTT‐Ca to BA/MMA monomers, the weight ratio of BA/MMA. The relationships between the mechanical properties and the core‐shell composite structures were elaborated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and electrochemical characterization of sulfonated polysulfone cation‐exchange membranes: Effects of the solvents on the degree of sulfonation

Sulfonated polysulfone cation‐exchange membranes with various degrees of sulfonation were prepared by a treatment with chlorosulfonic acid in different solvents of various polarities, and the effect of the solvent polarity on the degree of sulfonation was explored. These membranes were characterized by their ion‐exchange capacity, volume fraction of water, and electrochemical properties. The counterion transport numbers, permselectivity, and fixed charge densities of these membranes were estimated from membrane potential data and varied with the degree of sulfonation, concentration, and external salt concentration. The counterion mobility in the membrane phase was also estimated from membrane conductance measurements. These membrane were found to have good electrochemical properties and are suitable for various types of electromembrane processes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2344–2351, 2005     

Vacuum membrane distillation simulation of desalination using polypropylene hydrophobic microporous membrane

Numerical simulation is an effective method to get the optimal operating parameters in the chemical engineering process. In this work, the transport mechanism of vacuum membrane distillation (VMD) process was simulated and predicted by mathematical model, which was established based on the convective heat transfer coefficient, and 0.5M aqueous NaCl solution was concentrated with isotactic polypropylene (iPP) hydrophobic microporous membrane prepared via thermally induced phase separation (TIPS) in the VMD process. The as‐presented mathematical model simulated the effects of different operating parameters on the VMD performances for aqueous NaCl solution, such as feed temperature, feed flow rate, absolute pressure of membrane permeate side, temperature coefficient, membrane thickness, and porosity. A comparison between experimental data and simulated data was also considered to verify the proposed mathematical model. Additionally, the salt rejection of aqueous NaCl solution production water in VMD was higher than 99.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41632.     

Amphiphilic poly(vinyl chloride)‐g‐poly[poly(ethylene glycol) methylether methacrylate] copolymer for the surface hydrophilicity modification of poly(vinylidene fluoride) membrane

In this study, a comblike amphiphilic graft copolymer containing poly(vinyl chloride) (PVC) backbones and poly(oxyethylene methacrylate) [poly(ethylene glycol) methylether methacrylate (PEGMA)] side chains was facilely synthesized via an atom transfer radical polymerization method. Secondary chlorines in PVC were used as initial sites to graft a poly[poly(ethylene glycol) methylether methacrylate] [P(PEGMA)] brush. The synthesized PVC‐g‐P(PEGMA) graft copolymer served as an efficient additive for the hydrophilicity modification of the poly(vinylidene fluoride) (PVDF) membrane via a nonsolvent‐induced phase‐inversion technique. A larger pore size, higher porosity, and better connectivity were obtained for the modified PVDF membrane; this facilitated the permeability compared to the corresponding virgin PVDF membrane. In addition, the modified PVDF membrane showed a distinctively enhanced hydrophilicity and antifouling resistance, as suggested by the contact angle measurement and flux of bovine serum albumin solution tests, respectively. Accordingly, the PVC‐g‐P(PEGMA) graft copolymer was demonstrated as a successful additive for the hydrophilicity modification, and this study will likely open up new possibilities for the development of efficient amphiphilic PVC‐based copolymers for the excellent hydrophilicity modification of PVDF membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of poly(vinyl alcohol)‐poly(vinyl pyrrolidone) blend: A biomaterial with latent medical applications

Aqueous solutions of poly(vinyl alcohol) and poly(vinyl pyrrolidone) are blended and films are produced by casting method with the further intention of being used as bio‐materials with latent medical application. Glutaraldehyde, 4,4′‐diazido‐2,2′‐stilbenedisulfonic acid disodium salt tetra‐hydrate are used as crosslinker agents, whereas lactic acid is the plasticizer in the blend. The obtained films are characterized by differential scanning calorimetry (DSC), mechanical properties, swelling and solubility behavior. DSC measurements show that the blends exhibit a single glass transition temperature indicating that they are miscible, even in the presence of the plasticizer and crosslinker agents. By the combination of all mentioned additives, a relevant enhancement of the swelling is observed, accompanied by a stabilization of the solubility during the tested time. Finally, mechanical properties show an appropriate performance in the studied parameters. As a consequence, the obtained films could be suitable for use as medium or long‐term implants. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

One simple and stable coating of mixed‐charge copolymers on poly(vinyl chloride) films to improve antifouling efficiency

An antifouling surface is highly desirable for many biomedical applications. In this study, poly(vinyl chloride) (PVC) films were endowed with the improved properties of resisting nonspecific protein adsorption and platelet adhesion simply through being coated with a kind of mixed‐charge zwitterionic polymer, poly(3‐sulfopropyl methacrylate–methacrylatoethyl trimethyl ammonium chloride–glycidyl methacrylate) (PSTG), with random moieties of negatively charged 3‐sulfopropyl methacrylate potassium, positively charged [2‐(methacryloyloxy)‐ethyl] trimethylammonium chloride, and glycidyl methacrylate. The PSTG‐grafted PVC films were formed by the simple immersion of an amino‐functionalized PVC film into a PSTG solution. A grafting density of 220.84 µg/cm² of PSTG4‐grafted PVC film was successfully obtained. The PSTG4‐grafted PVC film showed a lower contact angle (37.5 °) than the ungrafted PVC film (98.3 °). The in vitro protein adsorption results show that the bovine serum albumin adsorption amount decreased 6.72 µg/cm² in the case of the PSTG4‐grafted PVC film, whereas that on the ungrafted PVC film was 28.54 µg/cm². So, PSTG‐grafted PVC films could be promising materials for medical devices. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44632.     

Effect of hydrophilic additive and PVC polymerization degree on morphology and electrochemical properties of PVC‐based heterogeneous cation‐exchange membrane

Membrane solution composition is one of the important factors that determine properties of ion‐exchange membranes. In this study, PVC‐based heterogeneous cation‐exchange membranes were prepared by the solution casting method. Effects of a hydrophilic additive [poly(ethylene glycol), PEG400] and degree of polymerization of poly(vinyl chloride) (PVC) on the morphology and electrochemical properties of the cation‐exchange membranes were investigated. The results revealed that the hydrophilic additive can improve membrane properties, including water uptake (Wu), ion‐exchange capacity (IEC), conductivity, and permselectivity. The improvements might be associated with an increase in accessibility of functional sites in the membrane matrix due to a higher hydrophilicity, indicated by a reduction of water contact angle and the greater void fraction shown by scanning electron microscopy. However, the permselectivity slightly decreased when the additive concentration was increased further. Meanwhile, increasing the degree of polymerization and PVC concentration resulted in higher permselectivity and lower conductivity, which might be due to a better resin distribution and a lower void fraction. Overall, the prepared membranes had relatively good conductivities (up to ～2.5 mS/cm) and permselectivities (up to ～0.92). In general the conductivity increased with increasing Wu and IEC, while the permselectivity showed the opposite trends. This could be associated with the efficacy of Donnan exclusion indicated by the IEC/Wu ratio and the Donnan equilibrium constant of the cation (K⁺). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46690.