Characterization of polyimide precursors using size exclusion chromatography with a light scattering detector

Abstract

Measurement of the molecular weight, radius and molecular weight distribution of polyimide precursors (amic acids and esters) is difficult due to the strong polymer-solvent interactions and possibility of electrostatic interactions. The large quantities of solvent and high dilutions necessary in liquid chromatography make this technique the most sensitive to these effects. The distortions in the chromatogram from these effects can make assessment of the molecular weight distribution from a polystyrene calibration tenuous. Use of a light scattering detector permits direct measurement of the scattering intensity (and thus the molecular weight), as the sample elutes from the column.