Correlation length of a near-critical, eight-arm star polystyrene in methylcyclohexane

The turbidity of eight-arm star polystyrene in methylcyclohexane has been measured and used to determine the correlation length amplitude $\xi _{0}$. The turbidity in this system was determined from the measured ratio of the transmitted to incident light intensities as a function of temperature. Various systematic errors were explored and eliminated in obtaining a value of $\xi _{0}$ for this branched polystyrene with a total molecular weight of 228,000. Ornstein-Zernike theory is used to fit the turbidity data. The value of $\xi _{0}$ is comparable to that reported in the literature for a linear polystyrene of the same molecular weight in methylcyclohexane. We acknowledge the support from NSF-REU grant DMR 0243811 and to the donors of the American Chemical Society Petroleum Research Fund.