High glass transition temperature shape‐memory materials: Hydroxyl‐terminated polydimethylsiloxane‐modified cyanate ester

Abstract

ABSTRACTHydroxyl‐terminated polydimethylsiloxane (HTPDMS) and hydrogenated bisphenol A‐type epoxy resin (AL‐3040) were coreacted with a silane coupling agent (KH‐550) to form an AL‐3040 epoxy resin–HTPDMS block copolymer. Then, the copolymer was used as a compatibilizer to modify cyanate ester with different mass ratios. Subsequently, the blend was cured to form HTPDMS‐modified shape‐memory cyanate ester. The soft Si─O─Si segments of HTPDMS act as a flexible unit that can be grafted with the crosslinked triazine structures of cyanate ester. It was excellent for the toughening modification of cyanate ester. With increasing mass ratio of compatibilizer and cyanate ester, the tensile strength and glass transition temperature (T g) of HTPDMS‐modified cyanate ester were decreased, whereas impact strength and elongation at break were increased. The shape‐memory tests exhibited that HTPDMS‐modified cyanate ester systems have excellent shape‐memory properties with a shape recovery rate of >96% and shape fixity rate of >97% and a recovery time of less than 110 s. Furthermore, Thermo‐Gravimetric Analyzer (TGA) tests showed that HTPDMS‐modified cyanate ester exhibited good thermal stability; the temperature of 10% mass loss was high at 365 °C. The char yield was increased with increasing contents of compatibilizer at 800°C. Therefore, HTPDMS modified cyanate ester exhibited much better heat resistance at high temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48641.