Synthesis And Properties Of Shape Memory Comb Polycaprolactone

Shape memory polymers have received extensive attention due to their advantages such as high degree of deformation,low induction temperature,and ease of processing.Polycaprolactone(PCL)is a medical material with excellent biodegradability and biocompatibility.However,polyester materials have the problems of slow recovery speed,low recovery rate,and poor shape memory stability.These problems greatly limit the application of polycaprolactone materials with shape memory properties.Therefore,the development of highperformance shape memory materials through structural design is the main research direction.In this paper,n-butyllithium is used as an initiator to obtain narrow distribution polybutadiene through living anionic polymerization,and then polyhydroxy polybutadiene is obtained through epoxidation and hydroxylation.Using polyhydroxy polybutadiene as a macroinitiator,gPCL-PLLA was synthesized by ring-opening polymerization and its shape memory properties were studied.gPCL,gP(CL-co-VL)were synthesized by the same method.A series of C-gPCL and C-gP(CL-co-VL)were synthesized.The properties of the cross-linked polymer obtained were characterized and the shape memory behavior of the cross-linked polymer was analyzed.The main content and results of the paper are as follows:(1)gPCL-PLLA are synthesized.When the content of polycaprolactone in gPCL-PLLA does not exceed 90%,the gPCL-PLLA has good shape memory effect.After 4 cycles,when the initial deformation is 50%,the shape fixation rate is 92.9% and the shape recovery rate is 95.9%.(2)C-gPCL based on comb structure is synthesized.The polymer has shape memory effect.After 5 cycles,when the initial deformation is 50%,the shape fixation rate is 92.6% and the shape recovery rate is 93.6%.(3)C-gP(CL-co-VL)is synthesized.As the molar content of valerolactone increases,Tc and Tm of C-gP(CL-co-VL)decrease first and then increase.When the content of valerolactone and caprolactone is the same,Tc andTm are the lowest.The cross-linked structure serves as a stationary phase and the comb-shaped precursor serves as a reversible phase.The shape memory temperature is adjustable and the shape stability is excellent.