Polymer characterization using gel-permeation chromatography (GPC) is invariably performed on polymer solutions and allows detailed analysis of different properties of the polymer molecules.
Polymer molecular weight (or polymer molar mass) is one of the key determinants of its bulk properties. For example, increased molecular weight can increase strength, while changing the polydispersity (the width of the range of molecular weights) can have effects on yield strength and brittleness. Measuring polymer molecular weight in solution using GPC is one of the primary tools of polymer characterization. The use of light scattering allows absolute molecular weight measurement regardless of the chemistry of polymer molecular structure.
As with molecular weight, levels of polymer branching and substitution have significant effects on the bulk physical properties of polymers. For instance, increased branching can improve polymer processability without reducing strength.
Intrinsic viscosity is a measure of polymer molecular structure relating to the conformation of the molecule. A tightly coiled, densely packed molecule has a low intrinsic viscosity and a high molecular density. This is related to any change in structure such as polymer branching or group substitution. Measuring polymer intrinsic viscosity with multi-detector GPC enables polymer branching to be quantified and differences in substitution levels to be assessed. This makes a viscometer detector, a tool for measuring polymer intrinsic viscosity, invaluable for high-level polymer characterization experiments.
Advanced GPC analysis of polymers in solution allows for the characterization of:
- Polystyrene molecular weight
- PEO molecular weight
- PEG molecular weight
- PLA molecular weight
- PLGA molecular weight
- Polycarbonate molecular weight
- PMMA, PVC, polybutadiene, nylon, PET, polyacrylamide, polycaprolactone, polyols, resins…
- …and any other soluble polymer!