Synthesis and characterization of silicone polyurea and mechanical properties improvement through interfacial reaction

Silicone polyurea typically exhibits inferior mechanical properties due to the microphase separation between the siloxane and polyurea segments. To address this issue, we propose a method to enhance the mechanical properties through interfacial reactions. The mechanical properties and microphase separation of silicone polyurea we synthesized were studied. And poly(isobutene-<i>alt</i>-maleic anhydride) (PBAM) and γ-aminopropyl triethoxysilane (KH550) which are capable of interfacial reactions were respectively introduced into polyurea and siloxane segments to reduce the degree of microphase separation and enhance the mechanical properties of silicone polyurea. The mechanism behind the improvement was elucidated through experimental results. FT-IR spectra confirmed that the maleic anhydride groups in PBAM and the amino groups in KH550 undergo rapid reactions. Additionally, it was observed that the rapid interaction of PBAM and KH550 at the interface made interfacial tension decrease fast through the pendant-drop method. Stability analysis and light microscope observations revealed that PBAM and KH550 can stabilize the two-phase interface, forming stable droplets within the mixture. Scanning electron microscopy (SEM) observations indicated a reduction in the degree of microphase separation in the silicone polyurea. Consequently, the introduction of PBAM and KH550 decreases interfacial tension and the dispersion size of the silicone phase within the carbon phase, thereby reducing the degree of microphase separation and enhancing the mechanical properties of the silicone polyurea.