Thermal stimuli response diphenylmethane diisocyanate-based polyurethane elastomer via adjustable silicon-induced distinctive microstructure

The segment character of polyurethanes (PUs) determines the micromorphology and properties. The effective segment regulation can customize the favorable performance of PUs. Herein, silicon covalent-modified polyurethanes (MPUs) were prepared by incorporating diphenylmethane diisocyanate (MDI) and diphenyl silanediol (DPSD) into PU molecules as hard segments via a two-step method. Distinctive microphase separation structures from sheet morphology to radial sheet or withered flower-like microdomain were formed by adjusting hydrogen bonding of hard segments and post-treatment techniques. Thus, with the addition of DPSD in hard segments, the thermo-optic responses for MPUs occurred due to the different microphase evolution under thermal effect. And with the further addition of DPSD, the effect of thermal stimuli on the transmittance gradually weakened. It was very clear that with increasing the temperature, the transmittance of MPUs showed a gradual increase owing to melting the microcrystals or destroying the ordered accumulation of hard segments. Meanwhile, the high mechanical properties were obtained, higher 15 times tensile strength and more than 100 times elastic modulus than those of pure PU as well as the excellent thermal stability. In sum, this study was of great significance for developing new functionalized PU materials.Highlights Polyurethanes were prepared by inducing modified silicon functionality. The distinctive microphase separation evolution of MPUs was found. Thermal stimuli responses showed a gradual decrease due to different structure. High mechanical properties and thermal stability were also obtained. SEM images showed that incorporating silicon groups into hard segments effectively adjusted the microstructure of polyurethane (PPU (A), PU1 (B), PU2 (C) and PU4 (D)). image