Properties of Water in Macromolecular Gels. IV. Proton Magnetic Resonance Studies of Water iu Macromolecular Gels

Abstract

Electrochemical and dilatometric studies have indicated that at least three states of water exist in macromolecular gels. The properties of each state of water in gels such as agarose gels were investigated by highresolution and broadline PMR over the temperature range from +50 to −60°C. The linewidth of water protons in gels was found to depend markedly on the water content of gels, and the linewidth vs. water content curve gave two inflection points. One of the inflection points can be attributed to the so-called bound water, but the other cannot be explained unless three states of water are assumed in gels. Three kinds of transition temperatures were confirmed by anomalous changes in the PMR linewidth below 0°C. The so-called bound water exhibited no transition temperature between 0 and −20°C, and free water gave the transition temperature at 0°C. Moreover, the transition temperature of a quantity of water was distributed in the range from 0 to −20°C. On the basis of the transition temperature, the properties of water in macromolecular gels are discussed.

Crystal Growth in Gels from the Mechanisms of Crystal Growth to Control of Polymorphism: New Trends on Theoretical and Experimental Aspects

“…However, if the pore size is small enough, there is a possibility that a higher supersaturation is needed, due to the compartmentalization of solvents. Finally, this may also represent an effect in the diffusion of substances [69][70][71].…”

Swelling behavior of radiation‐polymerized polyampholytic two‐component gels: Dynamic and equilibrium swelling kinetics

“…It has been suggested that water in natural macromolecular gels 28,29 or in synthetic hydrogels 30 can be of three types-namely, bulk water, interfacial water, and bound water, and they have been conveniently determined by techniques like dilatometry, specific conductivity, and differential scanning calorimetry. 31 For all practical purposes the three types of water have been grouped in two classes as freezable (bulk) water and nonfreezable (bound) water.…”

Wide-Range Control of Deswelling Time for Thermosensitive Poly(N-isopropylacrylamide) Gel Treated by Freeze-Drying

“…According to the previous paper, the poly(NIPAAm) gels in the deswelling state above the LCST have only bound water surrounding the polymer chains, except free bulk water . Since the bound water was considered not to freeze at 253 K, the FD treatment could not cause significantly to change the structure of polymer network at Q = 1.5. From these consideration, we deduced that water content in the process of freezing gel was an important factor to control the pore size.…”