ENHANCED MISCIBILITY OF POLYMER BLENDS THROUGH HYDROGEN BOND FORMATION (LCST, TG).

摘要

Roles of specific intermolecular interactions on miscibility of polymer blends have been systematically studied as hydrogen bond interactions were introduced into originally immiscible polymer blends of polystyrene (PS) without them; miscibility, phase separation and relaxation transition temperature behaviors were observed as a function of the introduced hydrogen bond concentration. Towards this end, p-(2-hydroxyl hexafluoroisopropyl)styrene was first synthesized by Grignard reation at high yield and copolymerized with styrene at various compositions. Specific intermolecular interactions were introduced by replacing the PS with the copolymers and mixing them with the counterpolymers containing various proton acceptor groups; poly(vinyl methyl ether), poly(vinyl acetate) poly(methyl vinyl ketone), poly(methyl methacrylate), poly(ethyl methacrylate), poly(butyl methacrylate), poly(styrene-co-acrylonitrile), poly(2,6-dimethyl-1,4-phenylene oxide), bisphenol A polycarbonate, an amorphous polyamide, two aliphatic polyesters, an aromatic polyester, poly(phenylene sulfone), and poly(dimethyl siloxane).; Enhanced miscibility by hydrogen bond formation was observed in various ways; solubility of two blend components in a common solvent was gradually changed, as the hydrogen bond concentration increased, from the solution containing two dilute phases of one component predominant concentration to the solution containing one concentrated phase of both components and one dilute phase via the homogeneous solution. Clarity of the resulting cast films was also changed from opaque to transparant. The transition point strongly depended on the characteristic of solvent engaged. Definitive miscibility determined from Tg behaviors of DSC showed its enhancement with the hydrogen bond formation.; Of the counterpolymers studied, all the vinyl polymers which had relatively flexible back-bones and proton acceptor groups on their side chains could be converted to miscible blends with the modified PS containing less than 9.67mol% of the hydroxyl group. However, the polymers containing both rigid phenylene and proton acceptor groups on their back-bones needed much more hydroxyl groups for miscibility, which were unusually high in the specific interation energy view point. It suggested free volume difference caused from molecular rigidity, polar-polar intermolecular interaction, and partial hydrogen bond formation as well as specific interaction, as main factors for determining miscibility. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI