Preparation of High-Performance One-Component Polysulfide Adhesives by Regulating Microphase Separation with Diisocyanate-Terminated Prepolymers and 1,4-Butanedithiol

The bad compatibility of liquid polysulfide (component A) and solid fillers (component B) induced an unsatisfactory curing or enhancement effect, which will lead to oil leakage, which limits their further application in aircraft fuel tank sealing. One-component curing by inserting a polyurethane structure into the polysulfide system is a viable approach to overcome the above shortcomings. In this work, a series of one-component polysulfide adhesives (OCPSs) were successfully prepared by using 1,4-butanedithiol (BSO) to replace 1,4-butanediol (BDO) as a chain extender, and their chemical structures, mechanical properties, thermal stability, microphase separation, and solvent resistance were systematically investigated. As expected, moderate microphase separation and more sulfur contents in the system provided OCPSs with better mechanical properties and water resistance. Moreover, OCPS-40 exhibited the best tensile strength, shear strength, and hardness of 22.43 ± 0.70 MPa, 2.47 ± 0.35 MPa, and 88 ± 3 Shore A, with 23.12-, 2.69-, and 1.32-fold improvement over the two-component polysulfide adhesives (TCPS-1225), respectively. Notably, the tensile strength of OCPS-40 could still reach 16.99 ± 0.80 and 14.87 ± 0.30 MPa after immersion in oil and water for 21 days, respectively. We believe that our paradigm can provide a feasible approach for designing high-performance one-component polysulfide adhesives.