Presented by: Prof. Stepan Podzimek, SYNPO Pardubice
Presented Live: June 5, 2025
Long-chain branching is a significant structural feature of synthetic and natural polymers, influencing many of their key features. Branching knowledge provides information on the kinetics of polymerization reactions as well as potential side reactions during polymerization.
Thousands of scientific publications have been published on the methodology of branching characterization and synthesis of various branched structures, demonstrating its importance.
Multi-angle light scattering (MALS) and viscometry of dilute polymer solutions are the primary analytical techniques for determining branching behavior.
Although both can be employed in batch mode without prior sample separation, combining the two procedures with an analytical separation yields more information in a shorter period of time.
Size exclusion chromatography (SEC) is one of the most widely used analytical techniques for characterizing synthetic and natural polymers. However, the tendency of branched polymers to become attached in the pores of column packing has a significant impact on their SEC separation.
Many branched polymers have ultra-high molar mass fractions that are susceptible to shear degradation in SEC columns. Asymmetric flow field flow fractionation (AF4) minimizes anchoring, resulting in more effective separation of branched polymers. AF4 greatly inhibits the shear degradation of polymer chains.
AF4-MALS serves as an ideal analytical tool for the characterization of polymers with high-molar-mass branched fractions, such as acrylic emulsion copolymers or elastomers, whereas SEC-MALS remains the preferred method for smaller branched macromolecules, such as drug-delivery polymers, various synthetic resins, and polyamides.
Both procedures can be accomplished using an online viscometer, which improves the sensitivity of branching detection and broadens branching research to tiny polymers.