title: pH effects on the complexation, miscibility and radiation-induced crosslinking in poly(acrylic acid)-poly(vinyl alcohol) blends.
abstract: The effect of pH on the complexation of poly(acrylic acid) with poly(vinyl alcohol) in aqueous solution, the miscibility of these polymers in the solid state and the possibility for crosslinking the blends using gamma radiation has been studied. It is demonstrated that the complexation ability of poly(vinyl alcohol) with respect to poly(acrylic acid) is relatively low in comparison with some other synthetic non-ionic polymers. The precipitation of interpolymer complexes was observed below the critical pH of complexation (pH(crit1)), which characterizes the transition between a compact hydrophobic polycomplex and an extended hydrophilic interpolymer associate. Films prepared by casting from aqueous solutions at different pH values exhibited a transition from miscibility to immiscibility at a certain critical pH, pH(crit2), above which hydrogen bonding is prevented. It is shown here that gamma radiation crosslinking of solid blends is efficient and only results in the formation of hydrogel films for blends prepared between pH(crit1) and pH(crit2). The yield of the gel fraction and the swelling properties of the films depended on the absorbed radiation dose and the polymer ratio. [Diagram: see text] SEM image of an equimolar PAA-PVA blend cast from a pH 4.6 solution.
authors.affiliation: Kazakh National University, Department of Chemical Physics and Macromolecular Chemistry, Karasai Batyra 95, 480012 Almaty, Kazakhstan.
authors.forename: Zauresh S
authors.initials: ZS
authors.lastname: Nurkeeva
authors.forename: Grigoriy A
authors.initials: GA
authors.lastname: Mun
authors.forename: Artem V
authors.initials: AV
authors.lastname: Dubolazov
authors.forename: Vitaliy V
authors.initials: VV
authors.lastname: Khutoryanskiy
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005720:Gamma Rays; D020100:Hydrogels / Q000138:chemical synthesis*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000180:Acrylic Resins; D020100:Hydrogels; D012996:Solutions; C006903:carbopol 940; D011142:Polyvinyl Alcohol