Dual silicon side chain modification of one-component polysulfide adhesives for excellent mechanical properties and solvent resistance

Silicon side chain modification is an effective way for improving solvent resistance of one-component polysulfide adhesives, but the introduction of silicon side chains decreases hydrogen bonding interactions, leading to some reduction in initial mechanical properties. Based on the silicon modification, inserting more hydrogen bonding sites into a system is a viable approach to solving the above problems. In this work, a series of novel silicon side chain-modified one-component polysulfide adhesives (Sis-OCPSs) were successfully prepared using chain extenders in different proportions: 1,4-butanedithiol (BSO) and 1,3-bis(trimethylsilyl)urea (BSU). As expected, the CO groups and dual silicon side chains in BSU provide more active sites and silicon content, effectively reinforcing mechanical properties and solvent resistance. The optimal overall performance was obtained when the mass ratio of BSO and BSU was 8 : 1. Compared to silane side chain modification (Si-OCPS3) and before modification (Sis-OCPS0), Sis-OCPS3 exhibited the highest tensile strength, elongation and shear strength of 23.75 ± 0.34 MPa, 439.03% and 4.72 ± 0.27 MPa, respectively. Moreover, the tensile strength of Sis-OCPS3 could still reach 20.86 ± 0.29 MPa and 19.04 ± 0.27 MPa after immersion in oil and water for 21 d. We believe our paradigm can offer a feasible approach for designing high-performance one-component polysulfide adhesives.