High-performance liquid chromatography polymerization mechanism

Anionic Catalysis Several bulky methacrylates afford highly isotactic, optically active polymers having a single-handed helical structure by asymmetric polymerization. The effective polymerization mechanism is mainly anionic but free-radical catalysis can also lead to helix-sense-selective polymerization. The anionic initiator systems can also be applied for the polymerization of bulky acrylates and acrylamides. The one-handed helical polymethacrylates show an excellent chiral recognition ability when used as a chiral stationary phase for high-performance liquid chromatography (HPLC) [97,98]. 

Gradient high-performance liquid chromatography (HPLC) has been useful for the characterization of copolymers (14-19). In such experiments, careful choice of separation conditions is a conditio sine qua non. Otherwise, low resolution for the polymeric sample will obstruct the separation. However, the separation in HPLC, dominated by enthalpic interactions, perfectly complements the entropic nature of the SEC retention mechanism in the characterization of complex polymer formulations. 

Cyclodextrins have previously been successfully employed in separation science. For instance, the partial separation and enrichment of optical and structural isomers as well as routine compounds based on selective precipitation with CDs have been reported [5,7-8]. Additionally, solutions of CDs have served as the mobile phase in a few thin-layer and high performance liquid chromatographic separations [5,9,10]. However, their most widespread application in chromatography has been as part of the stationary phase [5,6]. Various polymeric CD materials, CD gels or resins, as well as CD coated columns have been utilized as the stationary phases in the separation of many important classes of compounds [5,6,11-13]. Unfortunately, the use of these CD phases has been largely restricted to column or gas chromatography due to their low efficiency and/or poor mechanical strength [14-16]. 

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