As polymer networks infiltrated with water, hydro-gels are major constituents of animal and plant bodies and have diverse engineering applications. While natural hydro-gels can robustly adhere to other biological materials, such as bonding of tendons and cartilage on bones and adhe-sive plaques of mussels, it is challenging to achieve such tough adhesions between synthetic hydrogels and engineer-ing materials. Recent experiments show that chemically anchoring long-chain polymer networks of tough synthetic hydrogels on solid surfaces create adhesions tougher than their natural counterparts, but the underlying mechanism has not been well understood. It is also challenging to tune sys-tematically the adhesion of hydrogels on solids. Here, we provide a quantitative understanding of the mechanism for tough adhesions of hydrogels on solid materials via a com-bination of experiments, theory, and numerical simulations. Using a coupled cohesive-zone and Mullins-effect model val-idated by experiments, we reveal the interplays of intrinsic work of adhesion, interfacial strength, and energy dissipation in bulk hydrogels in order to achieve tough adhesions. We fur-ther show that hydrogel adhesion can be systematically tuned by tailoring the hydrogel geometry and silanization time of solid substrates, corresponding to the control of energy dis-sipation zone and intrinsic work of adhesion, respectively. The current work further provides a theoretical foundation for rational design of future biocompatible and underwater adhesives. 相似文献
Functional spheres : Monodisperse gold‐doped titania spheres with tunable sizes under high concentration of titanium precursor have been synthesized by introducing trace amounts of chloroauric acid into the reaction system. Surface photovoltage, surface photocurrent, and transient photovoltage measurements (see figure) of annealed samples reveal that gold nanodots can act as both electron acceptors and donors under the illumination of different wavelengths of light.
