Synthesis and properties of amphiphilic poly(methacrylic acid) copolymers possessing uniform polystyrene side-chains

Abstract

Poly(methacrylic acid) (PMAA) copolymers with uniform polystyrene (PS) side-chains were synthesized through the macromer technique. The graft copolymers (PMAA- g-PS) were purified by extraction with water and hot cyclohexane, and were then characterized by gel permeation chromatography, infra-red spectrophotometry and 1H nuclear magnetic resonance spectroscopy. The average grafting number was determined to be 3–7, and decreases with increasing conversion. The graft copolymers showed good emulsifying properties and high water absorbency, and can be used as a good compatibilizer for blending polystyrene with epichlorohydrin rubber (CHR). Only 2–3 wt% of the graft copolymer based on the blend was needed to enhance the mechanical properties of the blends, and the blends with weight ratio of PS CHR = 3 7 to 5/5 behave as good thermoplastic elastomers. When PMAA- g-PS was mixed with polyoxyethylene (PEO) grafted with PS in molar ratio of PEO PMAA = 1 , a thermoplastic intermolecular complex membrane was formed. This behaved as a chemical valve, as its permeability can be controlled reversibly by changing the pH value.