Tricritical Effect of Attractive and Repulsive Forces on a Single Polymer Coil in a Poor Solvent

Values of the reduction in swelling of a single coil in a poor solvent are calculated for the continuous-polymer model, by use of the renormalized theory. These values are compared to light-scattering measurements of Perzynski, Adam, and Delsanti. The results support recent theoretical studies of anomalous effects associated with the tricritical state of a polymer chain and ultraviolet divergences. In fact, this comparison provides the first experimental evidence of the existence of a tricritical state for polymers near the $\theta$ temperature.