EFFECT OF TEMPERATURE ON THE LIMITING VISCOSITY NUMBER OF HYALURONIC-ACID AND CHONDROITIN 4-SULFATE

The decrease in the limiting viscosity number [η] with temperature T for hyaluronic acid in nonalkaline solution and chondroitin 4‐sulfate in neutral and alkaline solutions may be expressed in terms of the temperature coefficient of the Kratky‐Porod persistence length a: d ln a/dT = −0.0040 (±0.0005). The result, while numerically somewhat smaller, resembles qualitatively that of cellulose derivatives. As in the latter case, standard conformational calculations underestimate the coefficient, which may be due to neglect of random occurrence of local conformational features of higher energy. In alkaline solution, large decreases in [η] of hyaluronic acid are accompanied by a positive temperature coefficient of [η]. This temperature effect is interpreted as an endothermal shift from the alkaline, low [η] form of the polymer to the neutral, high [η] form with increasing temperature. Copyright © 1979 John Wiley & Sons, Inc.