Separation of parent homopolymers from poly(ethylene oxide) and polystyrene-based block copolymers by liquid chromatography under limiting conditions of desorption – 1. Determination of the suitable molar mass range and optimization of chromatographic conditions

Fast and efficient single step liquid chromatography separation of parent homopolymers from block copolymers

The modified layout of the barrier method called liquid chromatography under limiting conditions of enthalpic interactions is presented. It enables automated quantitative separation of blends of synthetic polymers, for example the single step discrimination of both parent homopolymers from the block copolymers. Moreover, this method enables the estimation of molar mass and molar mass distribution of the block copolymer precursor. Adjacent large sequences of mobile phase of different composition are applied as barriers. They are created by a computer controlled pair of pumping systems in the form of longitudinal profiles along the column. The home synthesized block copolymers polystyrene-block-poly(2-vinylpyridine) served as model examples of the method application. The adsorption retention mechanism was exploited using mesoporous bare silica gel column packing. Series of block copolymers of similar composition can be quickly handled with the method to optimize their synthesis.

Method development in interaction polymer chromatography

Interaction polymer chromatography (IPC) is an umbrella term covering a large variety of primarily enthalpically-dominated macromolecular separation methods. These include temperature-gradient interaction chromatography, interactive gradient polymer elution chromatography (GPEC), barrier methods, etc. Also included are methods such as liquid chromatography at the critical conditions and GPEC in traditional precipitation-redissolution mode. IPC techniques are employed to determine the chemical composition distribution of copolymers, to separate multicomponent polymeric samples according to their chemical constituents, to determine the tacticity and end-group distribution of polymers, and to determine the chemical composition and molar mass distributions of select blocks in block copolymers. These are all properties which greatly affect the processing and end-use behavior of macromolecules. While extremely powerful, IPC methods are rarely employed outside academic and select industrial laboratories. This is generally because most published methods are "bespoke" ones, applicable only to the particular polymer being examined; as such, potential practitioners are faced with a lack of inductive information regarding how to develop IPC separations in non-empirical fashion. The aim of the present review is to distill from the literature and the author's experience the necessary fundamental macromolecular and chromatographic information so that those interested in doing so may develop IPC methods for their particular analytes of interest, regardless of what these analytes may be, with as little trial-and-error as possible. While much remains to be determined in this area, especially, for most techniques, as regards the role of temperature and how to fine-tune this critical parameter, and while a need for IPC columns designed specifically for large-molecule separations remains apparent, it is hoped that the present review will help place IPC methods in the hands of a more general, yet simultaneously more applied audience.

Determination of head addition incidence of (meth)acrylate and styrene in radical polymerization by RAFT block polymerization derivation and gradient polymer elution chromatography

Head addition incidences in RAFT polymerization can be calculated by a combination technology of RAFT block polymerization derivation and GPEC.