Synthesis and characterization of ABA-type block copolymers of trimethylene carbonate and ε-caprolactone

This paper describes the synthesis of a series of ABA-type triblock copolymers of trimethylene carbonate and c-caprolactone with various molar ratios and analyses the thermal and mechanical properties of the resulting copolymers. The structures of the triblock copolymers were characterized by H-1 and C-13 nuclear magnetic resonance spectroscopy, FT-IR spectroscopy and gel. permeation chromatography. Results obtained from the various characterization methods proves the successful synthesis of block copolymers of trimethylene carbonate and c-caprolactone. The thermal properties of the block copolymers were investigated by differential scanning calorimetry. The T-m and DeltaH(m) values of the copolymers decrease with increasing content of trimethylene carbonate units. Two T(g)s were found in the copolymers. Furthermore, both of the T-g values increased with increasing content of trimethylene carbonate units. The mechanical properties of the resulting copolymers were studied by using a tensile tester. The results indicated that the mechanical properties of the block copolymers are related to the molar ratio of trimethylene carbonate and c-caprolactone in the copolymers, as well as the molecular weights of the resulting copolymers. The block copolymer with a molar composition of 50/50 possessed the highest tensile stress at maximum and modulus of elasticity. Block copolymers possessing different properties could be obtained by adjusting the copolymer compositions. (C) 2004 Society of Chemical Industry.