Study on bulk preparation and properties of click chemistry end-crosslinked copolyether elastomers

Azide terminated ethylene oxide-tetrahydrofuran copolymer (ATPET) has been prepared through ethylene oxide-tetrahydrofuran copolymer (PET) end-capping modification. The FTIR and ¹³C NMR results indicate that the PET terminal hydroxyl was thoroughly replaced and yielded the target product ATPET with a theoretical azide content of 0.464 mmol g^-1. In comparison with PET, ATPET has lower viscosity. Using tripropargylamine as a cross-linker, elastomers with various functional molar ratios (R) were prepared by bulk CuAAC reaction. Mechanical tests indicate that with the increase in R, the mechanical properties exhibit a parabolic dependence on R. Swelling tests demonstrate that the apparent molecular weight of the elastomer effective elastic strands first decreases and subsequently increases with the increase in R. The dynamic mechanical analysis (DMA) reveals that the glass transition temperature of the elastomers is approximately -66°C. When R < 1.0, dangling strands are formed in the elastomers and cause a higher dissipation factor tan δ. Combined swelling with DMA, the network model of the elastomers is depicted. In addition, the elastomer thermal stability has also been studied.