How Much Force Is Needed To Stretch a Coiled Chain in Solution?

The solution temperature dependent ultrafiltration of linear polystyrene (PS) chains in cyclohexane was measured by using the Whatman membranes with two different pore sizes. A combination of static and dynamic laser light scattering (LLS) measurements enabled to accurately determine the relative retention concentration of longer chains under different macroscopic flow rates by using short chains under different macroscopic flow rates by using short chains as an internal reference. It was revealed that the force required to stretch linear polystyrene chains in cyclohexane is in the range 10-200 fN and qc is independent of the chain length. The measurement of the temperature dependence of qc might provide a better way to determine the true ideal point.