Chemical valves and gel actuators

Research News: Chemomechanical systems, based on porous polymers which undergo shape change or develop contractile forces in response to an external stimulus are attracting much interest as adjustable size‐selective permeation membranes for separating solute mixtures with different molecular size, in controlled drug release, or in actuators such as the gel looper shown in the figure which can move at a speed of 15 mm/min. equation image