Poly(Epichlorohydrin-CO-1,2-Epoxyhexane) - a promising precursor for an energetic azido polymer for cast-cure processing

A copolymer of epichlorohydrin (ECH) and 1,2-epoxyhexane (EpH) has been synthesized via cationic ring-opening polymerization using BF3xTHF as a catalyst and 1,4-butanediol (BDO) as an initiator. The structure of the resulting PECH copolymer was confirmed by NMR- and IR-spectroscopic methods. The molecular weight distribution was determined by GPC, showing a number average weight of 1607 g/mol. The introduction of n-butyl substituted units into the polyether backbone chain lowers the glass transition temperature, which was confirmed by thermal analysis (DSC-Tg), and also lowers the viscosity of the polymer significantly compared to PECH in the same molecular weight range. A subsequent azidation of the polymer should lead to an energetic prepolymer with interesting properties for cast-cure processing of composite propellants.