Synthesis and characterization of two shape-memory polymers containing short aramid hard segments and poly(ε-caprolactone) soft segments

A number of segmented copolymers were synthesized by reacting 4-aminobenzoyl end-functionalized poly(epsilon-caprolactone)s of M-n 2000, 3000 and 4000 g mol(-1) with three aromatic diacid dichlorides in the presence of chlorotrimethylsilane. Polymer purity, molar mass, thermal and mechanical properties were characterized by NMR, MALDI-TOF mass spectrometry, GPC, DSC, and DMTA. Promising shape-memory properties were observed for two polymers that contained comparatively short, semicrystalline poly(F-caprolactone) soft segments of molecular weight 3000 g mol(-1) and either terephthalamide or 2,6-naphthalenedicarboxyamide hard segments. Cast films of these polymers were soft and elastomer-like at room temperature. Loading could be conveniently achieved by cold-drawing at room temperature and strain recovery took place upon heating above the melting temperature of the soft segment (35 degrees C). Cast films reached uniform deformation properties with strain recovery rates as high as 99% and strain fixity values of 78% after passing through only one or two training cycles. (c) 2006 Elsevier Ltd. All rights reserved.