Thermoplastic polyurethane/silicone rubber (TPU/SiR) thermoplastic elastomers with fine phase structures and comfortable textures based on polymerization-induced phase separation

Abstract

In this study, the polymerization-induced phase separation (PIPS) method was employed to prepare thermoplastic elastomers (TPEs) without using any compatibilizers. Polydimethylsiloxane (PDMS) was dispersed in poly-tetramethylene-ether-glycol (PTMG) and subjected to phase separation during polymerization. The TPU/SiR TPEs obtained were composed of crosslinked silicone rubber (SiR) as the dispersed phase and TPU as the continuous phase. The chemical structures, phase morphologies, and mechanical properties of the obtained TPEs are easily tunable, with an average size of dispersed phase of ∼0.37 μm and a tensile strength of 13.5 MPa when the pre-polymerization time of TPU is 20 min and the SiR dispersed phase content is 22 wt%. After repetitive processing, the tensile strength of the recycled material can still reach approximately 80% of the initial value. Moreover, the material exhibits comfortable biological tactile performance, and the static and dynamic friction coefficients of this TPE with 33 wt% SiR are 0.512 and 0.246, respectively, which are much lower than those of pure TPU (U_s = 1.046; U_d = 0.544). This method provides a convenient and efficient way to prepare TPEs composed of two immiscible phases, and the regulation of the phase morphology is very flexible and simple compared with the traditional method.