Study on preparation and properties of polyether polytriazole elastomers

Abstract

To explore the application of click chemistry in the field of elastomer materials, propargyl-terminated ethylene oxide-tetrahydrofuran copolymer (PTP(E-co-T)) was prepared from hydroxyl-terminated ethylene oxide-tetrahydrofuran copolymer (P(E-co-T)) by end-etherisation modification. FTIR and 13C-NMR results indicate that P(E-co-T)-terminated hydroxyl was etherified thoroughly, yielding the target product PTP(E-co-T), and the content of terminated alkynyl of PTP(E-co-T) was evaluated to be 0.428 mmol·g−1. Using a polyazide compound as a cross-linker, polytriazole elastomers with various functional molar ratio (R) values were prepared from PTP(E-co-T) by virtue of the CuAAC reaction. Mechanical property tests indicate that with the increase in R, the modulus E and stress σ b of the polytriazole elastomers first increase and subsequently decrease, whereas the strain first decreases and later increases. The mechanical properties of the polytriazole elastomers show a parabolic dependence on the R value. Near the stoichiometric ratio, E and σ b show maxima and the strain ɛ b shows a minimum. Swelling tests demonstrate that the apparent molecular weight of polytriazole elastomer strands also first decreases and subsequently increases. At the stoichiometric ratio, the network structure possesses strands with a minimum apparent molecular weight and a maximum apparent density. Dynamic mechanical analysis reveals that the polytriazole elastomers presented damping peaks at approximately −64 °C, corresponding to the glass transition of copolyether strands, and the elastomer exhibited the lowest dissipation factor tan δ at the stoichiometric ratio. Thermal analysis suggests that the weight-loss process of the polytriazole elastomer is characteristic of one-step decomposition, and the elastomer begins to decompose from polyether strands, not triazole groups.