THERMODYNAMICS OF INTERACTION BETWEEN WAT ER AND COPOLYMERS OF ACRYLATE AND ACRYLIC-ACID

The thermodynamics of swelling of acrylate-acrylic acid copolymers in water has been studied for acrylates of different chemical nature. Kin etic and equilibrium properties of water vapor sorption, as well as th e values of factor of inaccessibility of copolymer polar groups for wa ter molecules calculated by the method of group contributions, testify that the polymer structure becomes more close during the sorption. Be cause copolymers are hydrophobic, they absorb water in cluster form. F or acrylic acid-methyl methacrylate and acrylic acid-methacrylate copo lymers the thermodynamic stability of aqueous solutions rises with inc reasing acrylic acid content, which is accompanied by the increase in negative enthalpy DELTAh(M) values. For copolymers in a high-elasticit y state DELTAS(m) > 0, while for glassy copolymers DELTAs(m) < 0. The dependences of DELTAh(m) and DELTAs(m) on the alkyl radical size have maximum, DELTAg(m) falls sharply with the increase in number of methyl ene groups, while all thermodynamic parameters tend zero.