MALS Detector Improves Polymer Research

Wyatt Technology Corp. has discovered that quantitative branching topology information is crucial in the development of novel polymer-based materials and for understanding polymerization processes.

A study by Wyatt scientists characterizes molecular structure in synthetic and natural polymers by multiangle light scattering (MALS). It also details the basic principles and significance of the detection and characterization of branching via the MALS detector and the various methods used.

A system for characterizing branched polymers comprises an HPLC tower along with the A4F control system and separation channel, a MALS detector and RI detector. Courtesy Wyatt Technology Corp.

“In order to identify and characterize branching, one needs information about the molar mass and the molecular size,” said Stepan Podzimek, scientific consultant for Wyatt Technology. “That is exactly the power of using a multiangle light scattering detector: it provides both pieces of information simultaneously and independently. The MALS detector is usually connected to an analytical separation technique, most commonly SEC (size exclusion chromatography), to determine branching parameters as a function of molar mass.”

He added that the MALS photometer and detector allow for direct determination of two parameters of interest, the branching ratio and the number of branch units per molecule.

The abnormal elution behavior of branched macromolecules in SEC was studied and used to explain the comparative data acquired by SEC-MALS and asymmetric flow field flow fractionation (A4F). The comparison of SEC-MALS and A4F-MALS proves superior, artifact-free A4F separation of large and highly branched macromolecules compared to their abnormal separation by SEC.

Podzimek analyzed branching in poly(lactic acid) using various instruments, including the MALS photometer, and discovered a solution to previous challenges in branching studies that were previously not possible without a multiangle light-scattering detector.

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