POLYMER GEL MANUFACTURING METHODS

Disclosed are a polymer gel in which a phase transition occurs due to a stimulus, a method of manufacturing such a polymer gel, and an actuator which employs such a polymer gel. The polymer gel which is formed by polymerizing monomers at a temperature equal to or less than a phase transition temperature of the resultant polymer gel and separating and/or classifying the polymer gel into fractions according to its size at a temperature equal to or greater than the phase transition temperature thereof. Alternatively, the polymer gel is separated and/or classified into fractions by adding a low molecular weight compound that can dissolve and swell the polymer gel to separate the polymer gel into fractions based upon a difference in dissolving rate or swelling rate. Alternatively separation and/or classification of the polymer gel is performed by a combination of the above-described two methods. In consequence, the resultant polymer gel has an average particle size ranging from 0.1 μm to 100 μm, and exhibits standard deviation of within 25 % of the average particle size. The width of the phase transistion peak of the resultant polymer gel as measured by DSC at a heating rate of 1 °C./min is within 10 °C. % of the