Synthesis, Morphology, and Properties of Polyurethane-triazoles by Click Chemistry

Facile Preparation and Properties of Crosslinked Copolyether Elastomers with 1,2,3-Triazole and Urethane Subunit via Click Polymerization

An azide terminated ethylene oxide-tetrahydrofuran copolymer with urethane segments (ATUPET) as a novel binder pre-polymer, has been prepared through ethylene oxide-tetrahydrofuran random copolymer (PET) end-capping modification via one-pot method. The structure characterization of the modifier has been analyzed by FTIR, 1H NMR, 13C NMR and GPC. In comparison with PET, ATUPET has a slightly higher viscosity because it has additional hydrogen bonding interaction generated by the urethane in ATUPET. Triazole cross-linked elastomers based on ATUPET with various functional molar ratios were prepared using tripropargylamine as a curing agent and cross-linker. Mechanical properties indicate that the modulus E and tensile strength σ b exhibit a parabolic dependence with the increase in R. At around the stoichiometric ratio, the modulus E and tensile strength σ b reach a maximum and the elongation at break exhibit an acceptable value at the same time. Swelling tests demonstrate that the apparent cross-linking densities (N0) have a maximum value at the stoichiometric ratio. Thermal analysis shows that the ATUPET prepolymer and its polytriazoles elastomers exhibit a satisfactory stability. The results demonstrated that ATUPET might be a promising polymeric binder for future propellant formulations especially in the field of isocyanate-free curing technology.

Synthesis of polyurethanes with pendant azide groups attached on the soft segments and the surface modification with mPEG by click chemistry for antifouling applications

Polyurethane with pendant azide groups on the soft segment (PU-GAP) was prepared in this study to further increase the content of reactive azide groups and improve their surfaces enrichment for further functionalization. Polymer diols with pendant azide groups (GAP) were prepared by transforming the pendant chlorine groups at polyepichlorohydrin (PECH) into azide groups with sodium azide. The prepared PECH, GAP and PU-GAP was characterized by GPC, ¹H NMR and FTIR. Propargylic mPEG (mPEG-alkyne) was used as model surface modification reagents which was grafted on the prepared azido containing polyurethane films via click chemistry. The surface morphology, chemical composition and wettabilities were studied by SEM, XPS and water contact angle (WCA) analysis, respectively. SEM results demonstrated different surface topologies between mPEG modified PU surface and original PU surface. XPS and WCA analysis proved the successful grafting of mPEG on the pendant azide groups of PUs. The mPEG modified PU surfaces demonstrated good antifouling activities against model bacteria and mPEG with larger molecular weights modified surfaces showed better resistance efficiency to attachment of bacteria. Therefore, the surface reactive polyurethane we prepared can be a universal platform for further functionalization according actual applications.

Polyurethane with pendant azide groups on the soft segment which can be an universal platform for further functionalization according actual applications.