Structure-Induced Switching of Interpolymer Adhesion by Polymer Chains Adsorbed onto a Planar Solid

We report a link between microscopic chain architecture and macroscopic adhesive property of polymer chains adsorbed on solids. Polyethylene oxide (PEO) was used as a model and two different chain conformations of the polymer adsorbed on silicon substrates were prepared. The adsorbed nanolayers consisted of densely packed “flattened chains”, and “loosely adsorbed polymer chains” which cover the flattened chains. Using a custom-built adhesion testing device, we investigated the adhesion properties of bilayers consisting of PEO overlayers atop flattened or loosely adsorbed chains. Results revealed that the flattened chains do not show any adhesive strength even when chemically identical polymer on top is above the melting temperature, while the loosely adsorbed chains exhibit adhesion. Neutron reflectivity and molecular dynamics simulations indicated that loops, whose size is above the threshold for entanglement, formed in the loosely adsorbed chains, bridging free chains and substrate surface. These findings shed light on interfacial structure-property relationships and provide a novel approach for developing adhesive technologies through precise control of interfacial polymer architecture.