The graft polymerization of vinyl benzoate and trans-stilbene onto polyurethane to control its mechanical and shape memory properties

Abstract

Vinyl benzoate (VB series) and trans-stilbene (SB series) were added onto polyurethane (PU) via graft polymerization, and the spectroscopic, thermal, tensile, shape memory, and low-temperature flexibility properties of the resulting polymers were compared with those of unmodified PU. The melting temperature ( Tm) and glass transition temperature ( Tg) of the soft segments are not significantly different for the VB and SB series compared with unmodified PU. The tensile strengths of the VB and SB series sharply increase with increasing vinyl polymer content, whereas the control series does not exhibit an increase in tensile strength. The VB series exhibits excellent shape recovery at 10℃ compared with unmodified PU, and the shape recovery of the SB series remains above 90% at 45℃. The shape retention values of the VB (−45℃) and SB series (–25℃) are not less than 90%. The selected PUs demonstrate better flexibilities at extremely low temperatures compared with unmodified PU. Therefore, the graft polymerization of vinyl benzoate or trans-stilbene onto PU improves the tensile strength, shape recovery at low temperatures, and low-temperature flexibility of the polymer without decreasing the tensile strain or shape retention.