Synthetic gels with switchable interfacial properties have great potential in smart devices and controllable transport. Herein, we design an organogel by incorporating a binary liquid mixture with an upper critical solution temperature (UCST) into a polymer network, resulting in reversible modulation of lubrication and adhesion properties. As the temperature changes, the lubricating mechanism changes reversibly from boundary lubrication to hydrodynamic lubrication due to phase separation within the binary solution permeating the gel (friction coefficient 0.4-0.03). Droplets appear on the gel surface at low temperature and disappear with temperature higher than the critical phase separation temperature (T ps) of the organogel. The organogel possesses a relatively low ice adhesive strength (less than 1 kPa). This material has potential applications in anti-icing and smart devices, and we believe that this design strategy can be expanded to other systems such as aqueous solutions and hydrogels.
To promote drop mobility, lubricating the gap between liquid drop and solid surface is a facile method which has been widely exploited by nature. Examples include lotus and rice leaves using entrapped air to "lubricate" water and Nepenthes pitcher plant using a slippery water layer to trap insects. Inspired by these, here, we report a strategy for transporting drop cargoes via the unidirectional spreading of immiscible lubricants on the peristome-mimetic surface. Oleophilic/hydrophobic peristome-mimetic surfaces were fabricated through replicating three-dimensional printed samples. The peristome-mimetic surface, via unidirectional immiscible hexadecane spreading, can transport a wide diversity of drop cargoes over a long distance with no loss with controllable drop volumes and velocities, hence mixing multiphase liquids and even reacting liquids. We anticipate this unidirectional drop cargo transport technique will find use in microfluidics, microreactors, water harvesting systems, etc.
Current hydrogel actuators mostly suffer from weak actuation strength and low responsive speed owing to their solvent diffusion‐induced volume change mechanism. Here a skeletal muscle‐inspired organohydrogel actuator is reported in which solvents are confined in hydrophobic microdomains. Organohydrogel actuator is driven by compartmentalized directional network deformation instead of volume change, avoiding the limitations that originate from solvent diffusion. Organohydrogel actuator has an actuation frequency of 0.11 Hz, 110 times that of traditional solvent diffusion‐driven hydrogel actuators (<10−3 Hz), and can lift more than 85 times their own weight. This design achieves the combination of high responsive speed, high actuation strength, and large material size, proposing a strategy to fabricate hydrogel actuators comparable with skeletal muscle performance.
The rapid development of wearable devices has an urgent demand for materials with switchable adhesion both in air and aqueous environments. Herein, we report a thermoresponsive ionogel with switchable adhesion...
Synthetic gels with switchable interfacial properties have great potential in smart devices and controllable transport. Herein, we design an organogel by incorporating a binary liquid mixture with an upper critical solution temperature (UCST) into a polymer network, resulting in reversible modulation of lubrication and adhesion properties. As the temperature changes, the lubricating mechanism changes reversibly from boundary lubrication to hydrodynamic lubrication due to phase separation within the binary solution permeating the gel (friction coefficient 0.4–0.03). Droplets appear on the gel surface at low temperature and disappear with temperature higher than the critical phase separation temperature (Tps) of the organogel. The organogel possesses a relatively low ice adhesive strength (less than 1 kPa). This material has potential applications in anti‐icing and smart devices, and we believe that this design strategy can be expanded to other systems such as aqueous solutions and hydrogels.
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