Retention Behavior of Linear, Branched, and Hyperbranched Polyesters in Interaction Liquid Chromatography

Abstract

The retention behavior of aromatic polyesters possessing different degrees of branching was studied in gradient liquid adsorption chromatography (gradient chromatography), liquid adsorption chromatography (LAC), and liquid chromatography at the critical conditions (LCCC). The chromatographic experiments revealed that retention of linear and branched polyesters is influenced by the degree of branching as well as the molar mass of the polymer samples in all enthalpy-dominated chromatographic modes such as LAC, LCCC, and gradient chromatography. At critical conditions of the linear polymer, the corresponding branched structures elute in the adsorption mode, indicating a stronger adsorptive interaction between the stationary phase and the branched polymer molecule. In gradient chromatography, polymer samples with higher degrees of branching are retarded longer on the stationary phase. A clear dependence between the degree of branching and the elution volume was found in both chromatographic modes, which clearly demonstrates a pronounced effect of topology on retention behavior. The results suggest the use of gradient chromatography as a first separation step for a two-dimensional characterization method of branched polymers in order to separate by both degree of branching and molar mass.

Characterization of mixed solutions of hyperbranched and linear polystyrenes by a combination of size‐exclusion chromatography and analytical ultracentrifugation

“…Lederer et al used SEC to fractionate linear and hyperbranched polyesters separately and further injected different fractions into SEC‐RI‐MALLS system to obtain the accurate molar mass of linear and hyperbranched samples. They found that the molar mass of the hyperbranched polyesters at the same retention volume was higher than that of linear samples.…”

“…[11] Moreover, the f/f 0 of hyperbranched sample is smaller than that of linear polystyrene, indicating the more symmetric structure of hyperbranched samples. [46] Lederer et al [47] used SEC to fractionate linear and hyperbranched polyesters separately and further injected different fractions into SEC-RI-MALLS system to obtain the accurate molar mass of linear and hyperbranched samples. They found that the molar mass of the hyperbranched polyesters at the same retention volume was higher than that of linear samples.…”

Viscosimetric detection in size‐exclusion chromatography (SEC/GPC): The Goldwasser method and beyond

“…Progresses in separation of polymers are of the highest importance to deal with the complexity of the new materials. Research in new separation methods such as field flow fractionation [45] or liquid adsorption chromatography [46] is gaining momentum. SEC has however more to offer than currently exploited.…”

The Combination of Liquid Chromatography and Mass Spectrometry Techniques for the Characterization of Aliphatic Polyesters

“…The potential applicability of gradient elution chromatography for polyester resins has been documented. [45][46][47][48][49][50] In most cases, reversed phase systems were used although the possibility of normal phase gradient HPLC has also been published. [51,52] The results of samples s23, s25 and s28 in Figure 6 are representative of the different stages of the polyesterification reaction thus the evolution of different species can clearly be followed.…”