The invention provides cryogels whose porosity, pore size, pore connectivity, swelling agent concentration, and/or specific volume undergoes a change from a first value to a second value in response to an electrical stimulus. The cryogels have interconnected macropores which greatly enhance their ability to rapidly undergo volumetric collapse when subjected to moderate electric fields. The cryogels of the invention can be easily integrated into arrays capable of rapid configurational and chromatic optical modulations, and when loaded with drugs, are able to coordinate the delivery profile of multiple drugs. The cryogel can be prepared by polymerizing an aqueous solution of charged monomers and cross-linker monomers at a temperature below the freezing temperature of the solvent.

Methods and compositions for improving performance of flocculants in an industrial production process. Methods include pH triggered cross-linking reaction between a flocculating agent, such as dextran, and a composition comprising a boronic acid-containing polymer. The pH trigger can be provided by a fluid having a pH of 8 or more. The production process can be a Bayer Process and the fluid is caustic liquor or slurry in the fluid circuit of the Bayer, wherein the reaction time is reduced over conventional methods and the cross-linked dextran composition effectuates improved flocculation of the trihydrate particles.