Enthalpy changes in the helix-coil transition of poly(gamma-benzyl L-glutamate)

The helix-coil transition temperature T_c of poly(γ-benzyl L -glutamate) in binary solvent mixtures of dichloroacetic acid and 1,4-dichlorobutane, 1-chlorooctane, or 1-chlorododecane have been measured. A treatment is presented with which the transition enthalpy can be calculated from the observed dependence of T_c on solvent composition. Results are compared with previously obtained calorimetric data. The underlying assumptions of the calculation are discussed.