Branched polymers
Posted: Tue Feb 26, 2019 4:18 pm
Can SEC-MALS analyze branched polymers?
Since both column calibration and universal calibration (with differential viscometry) depend on conformation, and usually there are no appropriate standards for branched polymers, neither column calibration nor universal calibration are applicable to branched polymers.
SEC-MALS does not rely on such standards and can, in fact, characterize branched polymers: 1) molar mass for all sizes of polymer; 2) rms radius and conformation for molecules larger than 10 nm. The addition of a third detector, a differential viscometer that determines intrinsic viscosity (IV) for SEC-MALS-IV, permits analysis of size and conformation across all size ranges, both below and above 10 nm.
Conformation plots help understand if the branching is long-chain or short-chain, as well as overall conformation (globular/condensed, random-coil, elongated/stiff, etc.). In Wyatt’s ASTRA software, you can compare known linear analogs to the branched polymers to determine branching ratio as a function of molar mass.
Learn more about analysis of conformation with MALS at www.wyatt.com/Conformation, and about MALS analysis of polymers at www.wyatt.com/Polymers.