Preparation of high-performance one-component polysulfide adhesives and modification by silane side chains

Abstract

One-component polysulfide adhesive preparation by diisocyanate-terminated prepolymers and 1,4-butanedithiol (BSO) can provide convenient moisture curing and excellent mechanical properties, but the formation of polysulfide-urea (–NHCOS–) groups causes some reduction in solvent resistance limiting their further application in aircraft fuel tank sealing. Introducing silane side chains into polysulfide adhesive systems is a viable approach to improving the solvent resistance. In this work, a series of novel silane side chain-modified one-component polysulfide adhesives were synthesized by using chain extenders in different proportions of BSO and (3-(2-aminoethyl)aminopropyl)trimethoxysilane (AEAPTMS). The results showed that a moderate amount of silane side chains and restricting the formation of Si–O–Si crosslinked networks can effectively enhance the elongation, interfacial interaction and solvent resistance. The optimal overall performance was obtained when the mass ratio of BSO and AEAPTMS was 7 : 1 (Si-OCPS3). Conversely, the oil and water absorption content after 21 days of Si-OCPS3 were 2.21 ± 0.06% and 2.81 ± 0.31%, being 20.50% and 43.57% lower than before modification (Si-OCPS0), respectively. Moreover, Si-OCPS3 exhibited higher tensile strength of 17.34 ± 0.66 MPa (oil) and 15.67 ± 0.32 MPa (water) than Si-OCPS0. We believe our paradigm can provide a feasible approach for designing high-performance one-component polysulfide adhesives.