Alkoxysilane functionalized polyurethane/polysiloxane copolymers: Synthesis and the effect of end-capping agent

A series of moisture curable polyurethane/polysiloxane (PUSR) copolymers with different end-capping agents were prepared based on amine terminated polysiloxane (PDMS), poly-1, 4-butylene adipate glycol (PBA), 4, 4'-diphenylmethane diisocyanate (MDI). The copolymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogarvimetric ( TGA), X-ray diffraction ( XRD), dynamic mechanical thermal analysis (DMTA), X-ray photoelectron spectroscopy ( XPS), surface contact angle and stress-strain measurement. Compared with conventional moisture curable PU, the PUSR copolymer showed the better thermal stability and surface properties due to the forming of Si-O-Si crosslinking network and the enrichment of siloxane chains on the surface of films, and the tensile strength was not obviously damaged. DMTA results suggested that micro-phase separation was formed in the PUSR copolymer. It was found that the PUSR copolymer with mixed alkoxysilanes as end-capping agents showed better compromised properties than that with single alkoxysilane.