Analysis of polystyrene-b-polyisoprene copolymers by coupling of liquid chromatography at critical conditions to NMR at critical conditions of polystyrene and polyisoprene
Date
2012
Authors
Sinha P.
Hiller W.
Bellas V.
Pasch H.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
For the investigation of the molecular heterogeneity of polystyrene-b-polyisoprene block copolymers, a chromatographic separation method, namely liquid chromatography at critical conditions was developed. This method was coupled on-line with
1H-NMR(where NMR stands for nuclear magnetic resonance) for the comprehensive analysis of the polystyrene-b- polyisoprene copolymers. The copolymers were synthesized by two different methods: sequential living anionic polymerization and coupling of living precursor blocks. While
1H-NMR allows just for the analysis of the bulk chemical composition of the block copolymers, the coupling with liquid chromatography at critical conditions provides selective molar mass information on the polystyrene and polyisoprene blocks within the copolymers. The polyisoprene block molar mass is determined by operating at chromatographic conditions corresponding to the critical point of adsorption of polystyrene and size exclusion chromatography mode for polyisoprene. The molar mass of the polystyrene block is determined by operating at the critical conditions of polyisoprene. In addition to the molar mass of each block of the copolymers, the chemical composition distribution of the block copolymers was determined. By using the coupling of liquid chromatography at critical conditions to
1H-NMR, one can also detect the homopolymers formed during synthesis. Finally the microstructure of the polyisoprene block in the copolymers was evaluated as a function of molar mass. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Description
Article
Keywords
Coupling of living precursor blocks, HPLC-
1H-NMR on-line hyphenation, Liquid chromatography at the critical point of adsorption, Poly(styrene-b-isoprene) diblock copolymers, Sequential living anionic polymerization
Citation
Journal of Separation Science
35
14
1731
1740
35
14
1731
1740