Synthesis of Self-Healing Polyurethane Urea-Based Supramolecular Materials

Supramolecular polyurethane ureas are expected to have superior mechanical properties primarily due to the reversible, noncovalent interactions such as hydrogen bonding interactions. We synthesized polyurethane prepolymers from small molecular weight of poly(tetramethylene ether) glycol and isophorone diisocyanates, which were end capped with propylamine to synthesize polyurethane ureas with high contents of urea and urethane groups for hydrogen-bonding formations to facilitate self-healing. The effects of polyurethane urea molecular weight (3000 <= M-n <= 9000), crosslinking, and cutting direction were studied in terms of thermal, mechanical, and morphological properties with an emphasis on the self-healing efficiency. It was found that the thermal self-healability was more pronounced as the molecular weight of polyurethane urea decreased, showing a maximum of more than 96% with 3000 Mn when the sample was cut along the stretch direction. (C) 2014 Wiley Periodicals, Inc.