Reversible Bonding of Aromatic Thermosetting Copolyesters for In-Space Assembly

Reversible bonding is an attractive option for assembly and disassembly of reconfigurable space structures due to the simplicity of the fastening concept. Interchain transesterifications reaction [ITR—a type of dynamic covalent exchange reactions afforded by aromatic thermosetting copolyesters (ATSP)] between two ATSP coatings can successfully be used as a reversible bonding concept, provided that the mode of debonding is completely cohesive (rather than adhesive or delaminatory from metal substrate). An optimization study is carried out on the ITR bonding for which ATSP coating is applied on 7075 aluminum substrates and bond/debond experiments are carried out using a custom-built tool kit. The toolkit enables precise control over bonding pressure, temperature, and contact time. Bonding conditions are optimized to produce complete cohesive failure with maximized bonding strength. Optimized bonding parameters are successfully implemented to realize 50 cycles of bond/debond process without compromising adhesive strength. Experiments show a debonding strength of 28.7 MPa for the 51st cycle at room temperature—significantly in excess of prior highest reversible bonding strength results found in the literature. These results, in addition to the high thermal stability and glass transition temperature of the base polymer, indicate viability of this reversible bonding concept for in-space assembly.