High response smart gels: Synthesis and application

Stimuli-responsive hydrogels change their volume and elasticity in dependence on the properties of the liquid phase. The amount of solvent uptake is dependent upon the chemical nature of the gel and the nature of its environment, e.g. solvent composition, temperature, pH, etc. The swelling/deswelling process is time consuming. For many applications the response time must be short. According to Tanaka's equation the rate of equilibration is inversely proportional to the square of gel size and proportional to the mutual (or cooperative) diffusion of the network and the solvent. D-coop is determined by the properties of the crosslinked polymer and can not be changed for a given chemical system. By decreasing the characteristic dimension of the gel, it is possible to reduce the time for equilibration. The synthesis, characterization of thin layers and small particles of T-sensitive polymers and their application in a micro-valve is described.