Synthesis and Reactivity of Hydroxypoly(ethylene oxide) propyl–b–polydimethylsiloxane–b–propyl hydroxypoly(ethylene oxide)

Abstract

A series of α, ω–bishydroxyl terminated PDMS, hydroxypoly(ethylene oxide) propyl–b–polydimethylsiloxane–b–propyl hydroxypoly(ethylene oxide) (HPEO–PDMS–HPEO) was prepared by a hydrosilation reaction of monoallyloxy substituted poly(ethylene oxide) with α,ω–bishydrogen terminated PDMS (HPDMS) that obtained via acid–catalyzed ring–opening polymerization of octamethylcyclotetrasiloxane with 1,1,3,3–tetramethyldisiloxane. Chloroplatinic acid was employed as the catalyst of hydrosilation. The molecular weight of HPEO–PDMS–HPEO could be controlled easily by varying the chain length of HPDMS. FTIR and 1H–NMR spectroscopy were used to identify the structure of HPEO–PDMS–HPEO and HPDMS. The conversion of Si–H bond to Si–C bond was affected by the catalyst amount, reaction time and temperature. It was found that the optimum condition of hydrosilation reaction was the catalyst amount of 22 μg/g and 5 h time at 100°C. Synthesized HPEO–PDMS–HPEO showed good storage stability at ambient temperature. Urethane reaction of OH and NCO group revealed that HPEO–PDMS–HPEO was more reactive toward to diisocyanate than α, ω –bishydroxylbutyl terminated PDMS.