Inhibition of Heterogeneous Nucleation in Water by Hydrogel Coating

Heterogeneous nucleation plays a critical role in the phase transition of water,which can cause damage in various systems.Here,we report that heterogeneous nucleation can be inhibited by utilizing hydrogel coatings to isolate solid surfaces and water.Hydrogels,which contain over 90%water when fully swelled,exhibit a high degree of similarity to water.Due to this similarity,there is a great energy barrier for heterogeneous nucleation along the water-hydrogel interface.Additionally,hydrogel coatings,which possess polymer networks,exhibit higher fracture energy and more robust adhesion to solid surfaces compared to water.This high fracture and adhesion energy acts as a deterrent for fracture nucleation within the hydrogel or along the hydrogel-solid interface.With a hydrogel layer approximately 100μm thick,the boiling temperature of water under atmospheric pressure can be raised from 100 to 108℃.Notably,hydrogel coatings also result in remarkable reductions in cavitation pressure on multiple solid surfaces.We have demonstrated the efficacy of hydrogel coatings in preventing damages resulting from acceleration-induced cavitation.Hydrogel coatings have the potential to alter the energy landscape of heterogeneous nucleation on the water-solid interface,making them an exciting avenue for innovation in heat transfer and fluidic systems.

The Dynamic Mortise-and-Tenon Interlock Assists Hydrated Soft Robots Toward Off-Road Locomotion

Natural locomotion such as walking,crawling,and swimming relies on spatially controlled deformation of soft tissues,which could allow efficient interaction with the external environment.As one of the ideal candidates for biomimetic materials,hydrogels can exhibit versatile bionic morphings.However,it remains an enormous challenge to transfer these insitu deformations to locomotion,particularly above complex terrains.Herein,inspired by the crawling mode of inchworms,an isotropic hydrogel with thermoresponsiveness could evolve to an anisotropic hydrogel actuator via interfacial diffusion polymerization,further evolving to multisection structure and exhibiting adaptive deformation with diverse degrees of freedom.Therefore,a dynamic mortise-and-tenon interlock could be generated through the interaction between the self-deformation of the hydrogel actuator and rough terrains,inducing continual multidimensional locomotion on various artificial rough substrates and natural sandy terrain.Interestingly,benefiting from the powerful mechanical energy transfer capability,the crawlable hydrogel actuators could also be utilized as hydrogel motors to activate static cargos to overstep complex terrains,which exhibit the potential application of a biomimetic mechanical discoloration device.Therefore,we believe that this design principle and control strategy may be of potential interest to the field of deformable materials,soft robots,and biomimetic devices.