A novel thermal curing reaction of oxetane resin with active diester

Abstract

Thermal curing reactions of oxetane resins {mixtures of novolac type oxetane (PNOX) with 2,2'-bis{(3-ethyl-3-oxetanyl)methoxy }biphenyl (2,2'-BPOX) and mixtures of tris{4-[(3-ethyl-3-oxetanyl)methoxy]phenyl}methane (THPMOX) with 2,2'-BPOX with active diester, 4,4'-isopropylidenebis(2,6-dichlorophenyl diacetate) (IBDCPA) were examined using certain quaternary phosphonium salts as catalysts. The thermal curing reaction of oxetane resins with IBDCPA proceeded smoothly at 170-190 °C to produce insoluble gel products. However, the rate of gel production was strongly affected by catalyst concentration and reaction temperature, and gel products were obtained in the highest yield when the reaction was carried out at 190 °C in bulk using 7 mol % of tetraphenylphosphonium chloride (TPPC) as a catalyst. The glass transition temperatures (Tg)s and 5 weight-% of loss temperatures (T d5%)s of the resulting gel products were determined by DSC and TGA analysis, and it was found that their Tgs and T d5%s were 97-118°C and 374-380°C, respectively, when the thermal curing reaction of oxetane resins PNOX/2,2'-BPOX with equivalent amount of cross-linker IBDCPA was performed using TPPC as a catalyst in bulk. On the other hand, the Tg and Td5%s of gel products obtained from the reaction of oxetane resins THPMOX/2,2′- BPOX with IBDCPA using the same catalyst were 96-128°C and 381-386°C, respectively. ©2008 The Society of Polymer Science.