CONFORMATIONAL TRANSITIONS IN INTERPOLYME R COMPLEXES [(POLY(METHACRYLIC ACID) GEL]-POLY(ETHYLENE GLYCOL)

The effects of molecular mass of the linear polymer and of temperature on the conformational state of the complex formed in aqueous media by poly(methacrylic acid) gel and PEG were examined. It was found that a s the concentration of PEG in solution increased, the gel first collap ses (at PEG concentration below 0.5-1.5%) and then, at higher concentr ations, reversible swelling of the gel takes place. Increasing the tem perature and the molecular mass of PEG was found to expand the concent ration range in which the gel is in the collapsed state. An important feature of reversible swelling of the gels of poly(methacrylic acid) i nteracting with PEG in a neutral medium is that a wide range of PEG co ncentrations exists, in which the gel may occur in the swollen and in the collapsed states.