Osmotic compressibility and correlation range of a macromolecular solution near its critical mixing point

From the angular distribution of the scattered-light intensity for polystyrene in cyclohexane near its critical mixing point, we have measured Ic,0T (Ic,0 being the extrapolated zero-angle scattering intensity), which is directly proportional to the osmotic isothermal compressibility χT, and the long-range correlation length ξ. We find (Ic,0T)^-1=B(TTₛₚ-1)^1.24±0.01 and ξ=(5.83±0.20)(TTₛₚ-1)^-0.62±0.02 {} along the isochore very near the critical concentration, and (Ic,0T)^-1=(2.3±0.1)B(1-TTc)^1.21±0.02 and ξ=(2.40±0.12)(1-TTc)^0.65±0.03 {} along the concentrated phase and (Ic,0T)^-1=(5.9±0.3)B(1-TTc)^1.25±0.03 along the dilute phase of the coexistence curve. In addition, we have determined the value of the critical exponent (δ4.4) which describes the concentration dependence of the chemical potential μ along the critical isotherm.