Separation of Branched Poly(bisphenol A carbonate) Structures by Solvent Gradient at Near-Critical Conditions and Two-Dimensional Liquid Chromatography

Abstract

Branching is a molecular metric that strongly influences the application properties of polymers. Consequently, detailed information on the microstructure is required to gain a deeper understanding of structure-property relationships. In the present case, we employ high-performance liquid chromatography to characterize the branching in a poly(bisphenol A carbonate) (PC). To this end, a method was developed based on a mobile phase gradient in a very narrow range (±1.4 vol %) around the point of adsorption (98.9/1.1 vol % chloroform/methyl tert-butyl ether), which we refer to as solvent gradient at near-critical conditions. Application of such gentle gradient enabled separation of PC according to end-groups. The separation mechanism was confirmed by collecting fractions of a separated sample and subsequently analyzing these by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Hyphenating the developed gradient method with size-exclusion chromatography as the second dimension (2D-LC) enabled separation of linear and branched PC chains and determination of the molar mass distribution of the fractions. A reversed elution order was observed for branched species in 2D-LC, meaning that low molar mass chains exhibited higher elution volumes in the first dimension than higher molar masses. This finding was explained by influences of end-groups as well as the architecture of the branched polymer chains.

Reaction kinetics of melt post‐polycondensation process for polycarbonate in film state

“…An APC chromatogram of MPP products of Con‐A at 260°C was presented in Figure 3. The peak gradually shifted to the left as the reaction time increased from 20 to 120 min, demonstrating that the molecular weight of PC increased continuously 32 . The change in M n for Con‐A and Con‐B during the MPP process was plotted as a function of time, as shown in Figure 4.…”

Recent Developments in Two-Dimensional Liquid Chromatography: Fundamental Improvements for Practical Applications

“…Apel et al performed RPLC in the first dimension with a very shallow gradient close to the critical conditions, followed by SEC in the second dimension to characterize branched poly (bisphenol A carbonate) structures. They combined this RPLC × SEC method with a triple-detector system (concentration detector, light scattering, and viscometry) and they tried to correlate the results with the outcome of Monte Carlo simulations .…”

Recent Advances in Separation-Based Techniques for Synthetic Polymer Characterization

“…In the same study, comprehensive 2DLC was used to separate the polydisperse star-shaped PS for both branching and molar mass characterization. Finally, branching in a poly­(bisphenol A carbonate) (PC) was characterized by a narrow composition range (only 1.4 volume percent change) solvent gradient at near critical conditions . The application of this gradient enabled separation of PC according to end-groups.…”

“…Branched polymers, block polymers, and grafted polymers were the topics of interest for several recent papers aimed at structural elucidation by multidimensional separations techniques. Branching distributions in PC samples were characterized by a technique the authors termed solvent gradient at near critical conditions in the first dimension and SEC in the second dimension . Solvent gradient at near critical conditions consisted of a very narrow range of solvent composition (from 100% chloroform to 97.5:2.5 v:v chloroform:methyl- t -butyl ether) near the critical point of adsorption, and in this case produced an interesting reversal of elution order compared to expected.…”

“…Finally, branching in a poly(bisphenol A carbonate) (PC) was characterized by a narrow composition range (only 1.4 volume percent change) solvent gradient at near critical conditions. 90 The application of this gradient enabled separation of PC according to end-groups. Fractions of the separated sample were collected and characterized by MALDI-TOF-MS to confirm the separation principle.…”