Method for the extraction of water from macromolecular solutions

Abstract

This invention pertains to a water-insolubilized resin of a polymer of at least one monomer selected from N-alkyl- or N-alkylene-substituted acrylamides or methacrylamides represented by the following general formula (I): ##STR1## wherein R.sub.1 and R.sub.2 mean individually a hydrogen atom or methyl group and R.sub.3 denotes a methyl, ethyl or propyl group, with the proviso that R.sub.3 is an ethyl or propyl group when R.sub.2 stands for a hydrogen atom, and that R.sub.3 is a methyl or ethyl group when R.sub.2 stands for a methyl group, or wherein R.sub.2 and R.sub.3 form --CH.sub.2).sub.4 or --CH.sub.2).sub.2 O--CH.sub.2).sub.2 in combination; or a copolymer of at least one monomer selected from the acrylamides or methacrylamides and another copolymerizable monomer. The resin has water-absorbing capacity which varies in degree depending on temperature and, when heated, undergoes shrinkage even in the presence of a large excess of water to release once-absorbed water. Because of this property, it may be used as a water-separating agent to remove water from a water-containing system. Since the resin can exhibit a sort of molecular sieve action, it can selectively control the concentration of a macromolecular material without affecting the concentration of a low molecular weight compound such as a buffer agent. The resin is useful particularly in concentrating an aqueous solution or emulsion containing a material susceptible to thermal denaturation, such as an edible substance, amino acid, protein, polysaccharide or, enzyme which is difficult to concentrate by the evaporation technique, and also in controlling the concentration of an aqueous solution while adjusting the degree of water-absorbing capacity of the resin by varying its temperature.