Partial crystalline organosilicon-based polysiloxane-polyurethane copolymers

Partial crystalline polysiloxane-based polyurethane copolymers were prepared by using hydroxyethoxypropyl capped polydimethylsiloxane (PDMS) as soft segment and alpha,omega-(bis (hydroxyethylthioether) ethyl)-disiloxane as chain extender. Due to this partial crystalline structure, the copolymer shows fairly good tensile properties and multiple shape deformation property. Repeated tensile tests revealed that stretch led to crystal destruction, and the microstructure of samples became stable after twice stretches. The lost crystallinity got 85.1% recovered upon treated at 60 degrees C for 1 h. It was proved that partial crystallization properties of the polysiloxane-polyurethane copolymer were from combined effects of polysiloxane soft segment and disiloxane chain extender. This unique crystallization kinetics of -(Si-O-Si)x- structure coexisting in soft and hard segments is regarded as one main reason to form crystalline hard segment domains in a common two-step synthesis.