A New Way to Measure Low Molecular Weight Polymer

Grubisic, et al (1967) [1] used the Einstein viscosity law (1906) [2] as a theoretical basis in calibrating a column for size exclusion chromatography (SEC) and it works well for polymer molecular weight (MW) from 10,000 to 11 million daltons. There are problems measuring polymer MW between 500 and 5000 daltons with SEC. For instance, Chance, et al (1995) [3] say that SEC for very low molecular weight suffers from intrinsic viscosities becoming negative for certain polymers due to packing effects. Also, how are the pores going to distinguish small polymers? Modern light scattering detectors, Podzimek (2014) [4], can effectively characterize polymers down to a several hundred daltons. Jennings (2012) [5] published an equation for bubble nucleation in polymer solutions that fairly well agrees with Jennings/Middleman data (1985) [6] and is a new way to measure polymer MW from polystyrene (PS) dimer up to about 5000 daltons. Jennings/Middleman used cyclohexane as the solvent and in this paper, it is easy to show how their equation can estimate low molecular weight polymers and details of the derivation will be shared.