Intermolecular interactions in the mixtures of semidilute aqueous solutions of poly(acrylic acid) and cellulose ethers

Intermolecular interactions in the mixtures of semidilute aqueous solutions of poly(acrylic acid) and two cellulose ethers (methyl cellulose and hydroxyethyl cellulose) were studied by the viscometry, sorption of solvent vapors, and IR spectroscopy. As was shown by the method of sorption of solvent vapors, in the mixtures of aqueous solutions of cellulose ethers and poly(acrylic acid), the interactions between polymer A and polymer B are so preferable that lead to the formation of interpolymer complexes. Viscometric measurements showed that, in the region of semidilute solutions, the concentration dependences of the viscosity of the poly(acrylic acid)-cellulose ether complexes are quite different from the similar dependences obtained for the complexes formed between poly(acrylic acid) and a flexible-chain polymer. As a result of the presence of hydrophobic groups in a macromolecule of methyl cellulose, the poly(acrylic acid)-methyl cellulose complex loses its solubility when passing to the region of semidilute solutions. The analysis of the corresponding IR spectra of the formed precipitate and a soluble phase showed that the precipitate is based on the poly(acrylic acid)methyl cellulose complex, which is stabilized by hydrogen bonds, whereas the soluble phase contains the excess of paly(acrylic acid).