Chemical modification of butyl rubber. I. Synthesis and properties of poly(ethylene oxide)‐grafted butyl rubber

Abstract

AbstractA new amphiphilic polymer, i.e., poly(ethylene oxide) (PEO)‐grafted butyl rubber (IIR‐g‐PEO), was synthesized by chemical modification of chlorinated butyl rubber (CIIR). This synthesis was based on the reaction between chlorine in CIIR and potassium salt of polyethylene glycol monomethyl ether (PEGM). PEGM's with molecular weights of 750 and 2000 were used. The maximum grafting percent of the resulted copolymers after the purification was ca. 45%, regardless of the molecular weight of PEGM. The microphase separated structure was observed in the films of IIR‐g‐PEOs. IIR‐g‐PEO, whose PEO molecular weight was 2000 and whose PEO content was 23.8 wt %, swelled 3.1% in water, and it was six times larger than the swelling of CIIR. The hydrophilicity of grafted polymers depended on the molecular weight of PEO side chains and PEO content. Even when the PEO contents were same in the polymers which were grafted PEGM‐750 and PEGM‐2000, their swellings in organic solvents were not equal. It was due to the difference of the microphase‐separated structures of the grafted polymers. IIR‐g‐PEO, whose PEO molecular weight was 750 and whose PEO content was 10.3 wt %, swelled 1.5% in water, but showed an excellent emulsifying ability, where an oil‐in‐water‐type emulsion was formed. © 1993 John Wiley & Sons, Inc.