Online hyphenation of size-exclusion chromatography and pyrolysis-gas chromatography for polymer characterization

An understanding of the composition and molecular heterogeneities of complex industrial polymers forms the basis of gaining control of the physical properties of materials. In the current work we report on the development of an online method to hyphenate liquid polymer chromatography with pyrolysis-GC (Py-GC). The designed workflow included a 10-port valve for fractionation of the first-dimension effluent. Collected fractions were transferred to the Py-GC by means of a second LC pump, a 6-port valve was used to control injection in the Py-GC, allowing the second pump to operate continuously. The optimized large volume injection (LVI) method was capable of analyzing 117 mu L of the LC effluent in a 6 min GC separation with a total cycle time of 8.45 min. This resulted in a total run time of 2.1 h while obtaining 15 Py-GC runs over the molar mass separation.The method was demonstrated on various real-life samples including a complex industrial copoly-mer with a bimodal molar mass distribution. The developed method was used to monitor the relative concentration of 5 different monomers over the molar mass distribution. Furthermore, the molar mass-dependent distribution of a low abundant comonomer (styrene, < 1% of total composition) was demon-strated, highlighting the low detection limits and increased resolving power of this approach over e.g. on -line NMR or IR spectroscopy. The developed method provides a flexible and widely applicable approach to LC-Py-GC hyphenation without having to resort to costly and specialized instrumentation.(c) 2023 The Author(s). Published by Elsevier B.V.This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

It is important to understand the composition and molecular heterogeneities of complex industrial polymers to control their physical properties. This study developed an online method that combines liquid polymer chromatography with pyrolysis-GC (Py-GC) to analyze the composition and molar mass distribution of industrial polymers. The method allows for fractionation of the first-dimension effluent and efficient analysis of complex samples.