Amylose in aqueous solution—a viscometric study

Abstract

A detailed investigation of the viscometric behaviour of amylose in aqueous solution has been made. The effect of pH, and of different alkalis and salts on the molecular conformation of the polysaccharide has been studied. It has been found that the limiting viscosity number [η] of amylose is constant up to pH 11 and thereafter increases rapidly, rising to a maximum in 0.15 M alkali. In the case of the inorganic alkalis, [η] subsequently decreases with increasing pH, but in tetramethylammonium hydroxide, a further slow increase in [η] occurs. In the presence of salts, this behaviour is completely modified, and a minimum in [η] is then found at pH 12. It is shown that the nature of the anion of the supporting salt greatly influences the conformation of the polysaccharide in both neutral and alkaline solution. The changes in [η] are related to changes in the shape of the dissolved macromolecule, and the manner in which the structure of the solvent water influences these changes is discussed.