Title: Elastocapillary Adhesion of Soft Gel Microspheres

Author (Talk): Katharine Jensen, Williams College

Abstract:

While elasticity has long been understood to be important in determining the relative stickiness between non-conformal surfaces, in recent years capillary forces have emerged as playing key roles in adhesion with highly compliant materials. In this work, we experimentally investigate the adhesion between polydimethylsiloxane gel microspheres and rigid glass substrates. By varying the asperity size and gel material properties, we observe a continuous transition from classic elastic to capillary-like adhesion, with contact line deformation mediated by a fluid contact zone that phase separates from the gel. Interestingly, the intermediate-compliance gels demonstrate a broad range of equilibrium contact deformations, reflecting a shallow energetic minimum that likely contributes to the robustness of everyday adhesives. We develop a new model incorporating elastocapillary and poroelastic mechanics that captures the complete range of adhesive behavior.