NMR relaxation and solvation equilibrium in the ternary system CCl₄‐polymethylmethacrylate‐benzene

In the ternary system CCl 4 ‐PMMA‐benzene, benzene is preferentially adsorbed in the solvation shell of the polymer. One solvation equilibrium constant allows a satisfactory description of the preferential solvation for a large range of solvent compositions. The nuclear magnetic relaxation time T 1 of benzene protons was measured for different values of the polymer concentration. The measurements are compared with analogous measurements in the system C 6 D 6 ‐PMMA‐C 6 H 6 where no preferential solvation is to be expected. For the system CCl 4 ‐PMMA‐benzene the resulting dimensionless solvation equilibrium constant is K = c 32 c 10 /c 12 c 30 = 2.5 ± 0.5 where c 10 is the CCl 4 concentration in the “free” solvent; c 30 is the benzene concentration in the free solvent; c 12 and c 32 are the concentrations of CCl 4 and benzene in contact with the polymer chain, respectively.