Preparation of HQEE modified PCL-based shape memory polyurethane
Poly(ε-caprolactone)(PCL)is a semi-crystalline polymer.Because of its good degradability and shape memory performance,the modification of PCL has been widely concerned and studied.Hydroquinone-bis(β-hydroxyethyl)ether(HQEE)was introduced into a poly(ε-caprolactone)(PCL)-based shape memory polyurethane with dendritic topology by molecular cross-linking.Hexamethylene diisocyanate was used as curing agent and trimethylolpropane as crosslinking agent.The prepared shape memory polyurethane(SMPU)was characterized by Fourier transform infrared spectroscopy,X-ray diffraction spectroscopy,ther-mogravimetry,differential scanning calorimetry and shape memory performance.The results show that all the isocyanate(—NCO)active groups participate in the reaction and SMPU samples are successfully prepared.The prepared SMPU are crystalline,and their crystallization performance decrease with the increase of chain extender(HQEE and 2,2,4-trimethyl-1,3-pentanediol)content.The thermal degradation performance is good,and the crystallization/melting peak occurr in the range of 30.9-40.2℃.The shape recov-ery ratio is 100%.The shape fixation ratio and shape recovery time decrease with the increase of chain extender content.The results show that the crystallization of SMPU-H2 and SMPU-H3 is moderate,and they have good shape memory performance.The hard segment content of SMPU-H2 and SMPU-H3 is 38.51%and 46.39%,respectively,and the shape memory transition temperature is 35.5℃and 34.7℃,respectively.
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