Synthesis and characterization of poly(siloxane‐urethane)s

Abstract

Abstract A series of polyurethane block copolymers based on hydroxy‐terminated polydimethylsiloxane and poly(propylene glycol) soft segments of molecular weights 1818 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′‐diphenylnethane diisocyanate and 1,4‐butanediol as the chain extender. Samples with different molar ratios were prepared. We tried to synthesize polydimethylsiloxane‐based polyurethanes (PDMS‐PU) containing a hard block as major fraction and a soft block as minor fraction for preparing toughened rigid systems. After a study of the pure polydimethylsiloxane‐based polyurethane and poly(propylene glycol)‐based polyurethane (PPG‐PU), (mixed polyol)‐based block copolymers and blends of PDMS‐PU and PPG‐PU were synthesized, and characterized by means of differential scanning calorimetry, tensile testing and scanning electron microscopy. In (mixed polyol)‐based copolymers and lower hard‐segment content blends, macro‐phase separation occurred, but blends with higher hard‐segment contents showed significant reduction in amounts of phase separation.