Study On The Preparation And Performance Of Poly(vinyl Alcohol) Polyampholyte Membrane Materials

Polyelectrolytes with polymer long chain and electrolyte of small molecule has dual structure characteristics, which is not possess functional properties for common polymer. Compared with nonionic polymers, polyelectrolytes has very good hydrophilic and charged, and stability in the water, so it is widely applied in many areas. In this paper, two polyampholyte were prepared by grafting the acrylamide, acrylic acid, sodium allylsulfonate onto poly(vinyl alcohol) (PVA) through grafting copolymerization and Hoffman degradation, then the structure and properties of synthesized materials were characterized.The synthesis and characterization of poly(vinyl alcohol)-g-poly(vinylamine -sodium acrylate)(PVA-g-P(VAM-SAC), PBPAâ… ): PVA-g-P(AM-SAC) was synthesized from PVA with acrylamide and sodium acrylate using potassium persulfate as an initiator, The PVA-g-P(AM-SAC) was degraded into PBPAâ… . Grafting polymerization were effected by initiator concentration, monomer concentration, reaction temperature and reaction time.The optimum reaction conditions of the experiments system were obtained through the single factor analysis method. The structures of PBPAâ… was characterized by infrared (IR) spectroscopy and scanning electron microscope(SEM). The characterized peaks of PBPAâ… groups were identified at 1666cm^-1, 1574cm^-1, 1567 cm^-1and 1416cm^-1 from IR spectrum. It can be recognized from photos of SEM that the morphology of modified PVA membranes was markedly changed compared with PVA. The results of DSC indicated that thermal stability of PBPAâ… was improved significantly compared with PVA. The water-resistance property of homogenous PBPAâ… membranes was best when the pH of PBPAâ… solution was 4, which also improved with the increase of annealing temperature. The water-absorption rate of PBPAâ… membranes was enhanced. The swelling behaviour in the organic aqueous solution indicated that the weaker the polar of organic, the better absorption of membrane to water.The synthesis and characterization of poly(vinyl alcohol)-g-poly(vinylamine -sodium acrylate)(PVA-g-P(VAM-SAS), PBPAâ…¡): PBPAâ…¡were prepared by grafting the acrylamide, sodium allylsulfonate onto PVA through grafting copolymerization and Hoffman degradation via initiator system of potassium persulfate. The optimum reaction conditions of the experiments system were obtained through the ortho-experiment and the single factor analysis method. The structures of PBPAâ…¡was characterized by IR spectroscopy and SEM. IR spectra of PBPAâ…¡existed the ammonium (1671 cm^-1 and 1570 cm^-1) and sulfonate (1201 cm^-1,1036 cm^-1 and 627 cm^-1) characteristic absorption peak besides the characteristic absorption peak of PVA. The random crosslinking morphology appeared in the SEM photos of PBPAâ…¡membrance. The results of DSC indicated that thermal stability of PBPAâ…¡was improved significantly compared with PVA. The water-resistance property of homogenous PBPAâ…¡membranes was best when the pH of PBPAâ…¡solution was 6, which also improved with the increase of annealing temperature. The water- absorption rate of PBPAâ…¡membranes was enhanced. The swelling behaviour in the organic aqueous solution indicated that the weaker the polar of organic, the better absorption of membrane to water.The IR characterization of homogenous PBPAâ… and PBPAâ…¡membranes absorbability: The water absorbability behaviors of two PBPA membranes were analyzed with 1D-IR and 2D-IR correlation spectroscopy in ethanol, acetone, isopropanol, acetic acid aqueous solution. IR results of variable concentrations showed that the separation selectivity of polyampholyte membranes was good in different organic aqueous solution except for acetic acid/water. 2D-IR results indicated that the water adsorption selectivity of high grafting ratio PBPA membranes was better. Two states of water, free water and associating water were revealed during permeation. The free water firstly was absorbed into membrane and associated with polyion groups, which formed associating water to reach the swelling balance finally.Pervaporation performance of composite PBPA membrance: 90℃, PBPAâ… and PBPAâ…¡menbrances were applied in the separation of acetic acid/water and isopropanol/water. The separation factorαis larger than 1000 and permeation flux J is more than 1000 g/(m²Â·h). thus, they are promising to industrial application as pervaporation membrane materials.In this paper, polyampholyte membranes are prepared once simple method and no precipitation exists. The 1D-IR and 2D-IR are used to research dehydration of organics, which provides a fast simple method of choosing membranes and new theoretical basis for explaining pervaporation process. PBPAâ… and PBPAâ…¡composite menbrances is expected to become the industrialized applicaton using organic dehydration.