Adsorption-exclusion behaviour of polyethylene glycol macromolecules during chromatography

2D-LC/SEC-(MALDI-TOF)-MS Characterization of Symmetric and Nonsymmetric Biocompatible PEOm–PIB–PEOn Block Copolymers

“…The critical adsorption point (CAP), where all structural units of the polymer coelute together with the initial solvent regardless of their chain length, is given by the compensation of enthalpic and entropic driving forces. By addressing a careful match among the solvent composition, the respective polymer, and the polarity of the used separation matrix, the distribution coefficient is set to K = 1 and the interaction parameter c = 0, − to achieve the conditions required for a size independent, but polarity dependent, analysis of the polymers. In the analysis of di- and triblock copolymers (A n B m or A n B m A n types), the chromatographic separation method is usually based on the critical condition of the homopolymer A (LCCC) leading to an elution of a block copolymer now depending on the exact nature of its interaction with the stationary phaseeither in the exclusion (SEC) or the adsorption mode (LAC).…”