Nature of aquananoassociates in hydrogels based on cross-linked poly-N-vinylcaprolactam

The behavior of water in a model system on the basis of poly-N-vinylcaprolactam cross-linked with divinylbenzene (melting, evaporation, and fractionation of water-polymer mixtures) is studied by differential scanning calorimetry. Varying the water content in the polymer matrix shows that there are three coexisting states of water. The properties of nanoassociates composed of hydrate shells in the vicinity of polymer chains with high concentration of amide groups are considered. An explanation of the effect of the polymer matrix on the parameters of the phase transitions is proposed, which is based on the strong polarizing action of the CO of amide groups on water molecules surrounded by segments of polymer chains with syndiotactic structure and chair-conformation caprolactam rings.The behavior of water in a model system on the basis of poly-N-vinylcaprolactam cross-linked with divinylbenzene (melting, evaporation, and fractionation of water-polymer mixtures) is studied by differential scanning calorimetry. Varying the water content in the polymer matrix shows that there are three coexisting states of water. The properties of nanoassociates composed of hydrate shells in the vicinity of polymer chains with high concentration of amide groups are considered. An explanation of the effect of the polymer matrix on the parameters of the phase transitions is proposed, which is based on the strong polarizing action of the CO of amide groups on water molecules surrounded by segments of polymer chains with syndiotactic structure and chair-conformation caprolactam rings.A