Liquid adsorption chromatography (LAC) and gradient polymer elution chromatography (GPEC)
As the structure of a polymer becomes more complex its characterization can present unique challenges. For example, spectroscopic techniques provide only average values of composition for copolymers, not detailed composition distributions. For such systems, LAC/GPEC, a polymer chromatographic mode relying on the differential affinities between polymers, solvents and columns, is extremely powerful. Precipitation/redissolution and adsorption/desorption mechanisms control the separation of fractions, providing detailed information about the chemical composition of the material under study.
The LAC/GPEC method is typically applied to:
- Characterize the homogeneity of a copolymer composition distribution
- Distinguish between copolymers and blends
- Deformulate complex polymeric systems