Soft Gel-Filled Composite Adhesive for Dry and Wet Adhesion

We have presented a two-phase adhesive for both dry and wet adhesion applications and for using it over repeated bonding and debonding cycles. We have dispersed a hydrogel phase in the continuous matrix of an elastomer, both cross-linked in situ almost simultaneously. Adhesion tests showed that although the individual phases were elastic and displayed negligible adhesion hysteresis, for the two-phase adhesive, hysteresis increased with the content of the dispersed phase in the material, eventually attaining maxima at an intermediate loading. Hysteresis also increased with the rate of separation of the adherents. Experiments showed that such enhancement in hysteresis could not be explained by considering the bulk viscoelastic effect of the two-phase material, as the two-phase composites too are essentially elastic, similar to the individual phases. Instead, intrinsic, rate-dependent, interfacial interactions born out of topographical and chemical heterogeneity of the adhesive surface could account for it. The adhesive could be used for both dry and wet conditions; in fact, adhesion was stronger on a wet adherent. It could also be used over 50 times without any alteration in adhesion. The adhesion mechanism is expected to be useful for a host of diverse applications.

Automated summary

The study introduced a two-phase adhesive suitable for both dry and wet conditions, with a dispersed hydrogel phase within an elastomer matrix. Experiments revealed that the adhesion hysteresis of the two-phase adhesive was related to the content of dispersed phase and separation rate, and was attributed to intrinsic, rate-dependent interfacial interactions.