Characterization of Polystyrene‐block‐Polyethylene Oxide Diblock Copolymers and Blends of Homopolymers by Liquid Chromatography at Critical Conditions (LCCC)

Abstract

Summary: In the present study, diblock copolymers of PS-b-PEO synthesized by sequential living anionic polymerization as well as the blends of PS, PEO homopolymers will be investigated by using liquid chromatography at critical conditions. Critical conditions will be established for the PS block of the copolymer. At these conditions, the PS block is chromatographically invisible and does not contribute to retention so the block copolymer is separated according to the block length of the PEO block. At the critical conditions of PS, it is also possible to separate the PS homopolymer formed. The critical conditions will be established in such a way that the non-critical PEO block elutes in size exclusion chromatography (SEC) mode.

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

“…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). Starting from the well-known LCCC conditions of PEO- and PMMA-based polymers, a large variety of different A n B m block copolymers (e.g., poly(ethylene oxide)- b -poly(propylene oxide), polystyrene- b -poly(ethylene oxide), and polystyrene- b -poly(methyl methacrylate)) have been analyzed using either one- or two-dimensional chromatography, ,,− where the block composition varies strongly in their polarities . Especially, the direct coupling of one- and two-dimensional chromatographic methods to mass spectrometry (MALDI and ESI) − has enabled to effectively combine the separation of BCPs based on functionality and hydrodynamic volume (SEC) into an online two-dimensional system, where an orthogonality criterion is fulfilled via distinctive separation mechanisms .…”

Separation of Parent Homopolymers from Polystyrene-b-poly(ethylene oxide)-b-polystyrene Triblock Copolymers by Means of Liquid Chromatography: 1. Comparison of Different Methods

“…Critical conditions for PEO , have been established, while PS eluted in the SEC mode. Conversely, at critical conditions for PS, the exclusion eluted block was PEO. , The important issue concerning critical conditions for PEO is that most reported studies were carried out with a mobile phase composed of water and water miscible organic solvents such as acetone, acetonitrile, methanol, etc. Such mixtures are restricted to the PEO-based block copolymers, in which the second block exhibits similar solubility ,, or its molar mass is sufficiently low to avoid precipitation.…”