writer：Linbo Wu*, Wu, LB; Jin, CL; Sun, XY
keywords：Stimuli-Responsive Materials; Biodegradable Light-Induced Shape Memory Polymers; Photoresponsive Polymers; Biodegradable polymers; Multiblock Copolymers
source：期刊
specific source：BIOMACROMOLECULES 12(1): 235-241, 2011
Issue time：2011年

Novel multiblock polyesterurethanes containing crystalline hard and amorphous soft segments and pendant
cinnamamide moieties were designed and synthesized via a two-step polyaddition reaction using N,N-bis(2-
hydroxyethyl) cinnamamide (BHECA), biodegradable poly(L,L-lactide) (PLLA), and poly(ε-caprolactone) (PCL)
diols as raw materials and hexamethylene diisocyanate (HDI) as coupling agent and characterized by 1H NMR,
FTIR, UV, DSC, tensile and photomechanical tests, and so on. The copolymers behaved as typical thermoplastic
elastomers and showed satisfactory thermal and mechanical properties. They also exhibited light-induced shape
memory effect (LSME) at room temperature on exposure to light stimuli. The pendant cinnamamide groups work
as photoresponsive molecular switches and provide the polymer with LSME via reversible [2 + 2] cycloaddition
cross-linking. The strain fixity (Rf) increases with the content of BHECA and the strain recovery (Rr) increases
with the content of PLLA. The Rf reaches 50% at a BHECA content of 20 wt % and the Rr reaches >95% at
PLLA content of 50 wt %.