No abstract

Surfaces with controllable wettability can be fabricated by embedding superhydrophobic particles into stimuli-responsive hydrogels. When the hydrogel changes its size due to a specific stimulus, the wettability of the surface can be reversibly tuned from superhydrophobic to superhydrophilic. This general method is used to fabricate "smart" membranes for controlling the permeability of chemicals under the influence of multiple stimuli simultaneously.

When water droplets (e.g., from rain) flow down a solid surface due to gravity, they can generate power.

No abstract

Charged liquid droplets are typically generated by a high-voltage power supply. Herein, a previously unreported method is used for charging liquid droplets: by transferring charge from an insulating solid surface charged by contact electrification to the droplets. Charging the solid surface by contact electrification involves bringing it into contact with another solid surface for generating static charge. Subsequently, water droplets that flow across the surface are found to be charged-thus, the charge is readily transferred from solid to liquid. The charge of the droplets can be tuned continuously from positive to negative by varying the way the solid surface is charged. The amount of charge generated is sufficient for manipulating, coalescing, and sorting the water droplets by solid surfaces charged by contact electrification. This method of generating charged droplets is general, simple, inexpensive, and does not need any additional equipment or power supply.