NEW AMPHIPHILIC COPOLYMERS OF N-PHENYLMALEIMIDES AND VINYL ETHERS - THERMAL-PROPERTIES, LANGMUIR AND LANGMUIR-BLODGETT-FILMS, GAS PERMEATION

Amphiphilic copolymers 1a-1d were prepared by radical copolymerization of hydrophilic N-phenylmaleimide derivatives and lipophilic vinyl eth ers in dichloromethane. Though the starting concentrations of the two monomers were always equimolar, none of the copolymers had a strictly alternating structure. Molecular weights were between 10(4) and 9 . 10 (4). The copolymers prepared from ethyl 4-maleimidobenzoate (2a) and i sobutyl vinyl ether (3a) (copolymer 1a), and 2a and isooctyl vinyl eth er (3b) (copolymer 1b) were thermally stable up to 300 degrees C and s howed glass transitions at about 150 degrees C, while the copolymers p repared from 2 a and octadecyl vinyl ether (3c) (copolymer 1c), and 4- maleimidobenzoic acid (2b) and 3c (copolymer 1d) were considerably les s stable. All copolymers formed stable, condensed monomolecular layers at the air-water interface, which could be transferred onto hydrophob ic supports by the Langmuir-Blodgett (LB) technique. Up to the 20th di pping cycle, a Y-type deposition was found, while further dipping pred ominantly led to Z-type deposition. Nitrogen and oxygen permeabilities (P) were studied after depositing the LB films onto porous Celgard me mbranes. Permeability and selectivity were dependent on the nature of the alkyl substituent group of the polymer. Copolymer 1a with the isob utyl group showed higher permeabilities than copolymer 1c with the oct adecyl group, but no selectivity. The copolymer with the small alkyl g roup showed no selectivity of oxygen over nitrogen (alpha = P-O2/P-N2) , while for the copolymer with the long alkyl chain the alpha-value wa s 1,3.