Biodegradable and Photocurable Multiblock Copolymers with Shape-Memory Properties from Poly(ε-caprolactone) Diol, Poly(ethylene glycol), and 5-Cinnamoyloxyisophthalic Acid

Biodegradable and photocurable multiblock copolymers of various compositions were synthesized by the high-temperature solution polycondensation of poly(e-caprolactone) (PCL) diols of molecular weight (M-n) = 3000 and poly(ethylene glycol) s (PEG) of M-n = 3000 with a dichloride of 5-cinnamoyloxyisophthalic acid (ICA) as a chain extender, followed by irradiation by a 400 W high-pressure mercury lamp (lambda > 280 nm) to form a network structure. The gel contents increased with photocuring time, reaching a level of over 90% after 10 min for all copolymers without a photoinitiator. The thermal and mechanical properties of the photocured copolymers were examined by DSC and tensile tests. In cyclic thermomechanical tensile tests, the photocured ICA/PCL/PEG copolymer films showed good shape-memory properties at 37-60 degrees C, with both shape fixity ratio and shape recovery ratio over 90% at a maximum tensile strain of 100-300%. The water absorption of these copolymers and their rate of degradation in a phosphate buffer solution (pH 7.0) at 37 degrees C increased significantly with increasing PEG content. The novel photocured ICA/PCL/PEG multiblock copolymers are potentially useful in biomedical applications. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 3556-3564, 2011