Topology and Dynamic Regulations of Comb-like Polymers as Strong Adhesives

Strong adhesives as structural load-bearing materials can provide both adhesive bonding to substrate surfaces and cohesive bonding throughout the bulk material, which are widely used in the cement nail, electronic device, and automotive industries. By a molecular topological regulation, in this work, we developed a series of strong adhesives based on comb-like polymers. By systematically regulating the topological parameters including the side chain length, the spacer between side chains, and the degree of polymerization of the overall backbone, comprehensive studies on linear rheology (the terminal relaxation time and zero viscosity) and non-linear debonding adhesion (the work of adhesion) are performed on these comb-like polymers. It was found that the rheological behaviors depend not only on the structure parameters but also on whether or not the samples exhibit phase separation. Moreover, regardless of the topological structure of comb-like polymers with strong and weak phase separation, the universal work of adhesion is observed to be dependent on the multiplication of terminal relaxation time and the debonding rate, indicating dynamic control over the nonlinear work of adhesion. Furthermore, comb-like polymers are feasible to bind with diverse substrates, including glass, polypropylene and polyethylene terephthalate, wood, and metal. In comparison to existing works using dynamic physical or chemical bonds, molecular topology regulation is more easily fulfilled in strong adhesives without the use of additives and complicated chemical and physical modifications, lowering the barrier for practical applications.