Thermoresponsive chemically crosslinked poly(N-vinylcaprolactam) gels

Spherical granules of a crosslinked hydrophilic poly(N-vinylcaprolactam) ge l were obtained for the first time by radical polymerization of hydrophobic N-vinylcaprolactam in water in the absence of surfactants. The size of gra nules can be controlled by introducing various crosslinking agents into the gel composition. Factors affecting the sorption ability of granules includ e the structure and amount of a crosslinking agent and the temperature of s welling. It was established that the rate of sorbate diffusion varies in th e course of sorption. The effective diffusion rate of water molecules in th e gel markedly decreases at a temperature of 40 degrees C, which is indicat ive of a phase transition with a partial loss of water from the gel. The ch emical crosslinks modify the chain conformation, thus controlling the degre e of hydration of the carbonyl groups in poly(N-vinylcaprolactam).