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Co‐Micellization Investigated by Pulsed Field Gradient‐NMR Spectroscopy
Author(s) -
Gröger Stefan,
Geschke Dieter,
Kärger Jörg,
Stallmach Frank,
Koňák Čestmír
Publication year - 2004
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200400016
Subject(s) - copolymer , polystyrene , pulsed field gradient , dynamic light scattering , spectroscopy , nuclear magnetic resonance spectroscopy , micelle , analytical chemistry (journal) , chemistry , polymer , materials science , polymer chemistry , aqueous solution , chromatography , molecule , organic chemistry , nanotechnology , physics , quantum mechanics , nanoparticle
Summary: Pulse field gradient‐NMR (PFG‐NMR) spectroscopy is determined to be a more suitable method for the investigation of self‐association processes in multi‐component (co)polymer systems than light scattering methods. Here the co‐micellization of mixtures of the diblock copolymer polystyrene‐ block ‐(hydrogenated polyisoprene) (PS‐HPI) and the triblock copolymer polystyrene‐ block ‐(hydrogenated polybutadiene)‐ block ‐polystyrene (PS‐HPB‐PS) in decane is investigated by PFG‐NMR spectroscopy and the results compared to those experimentally determined by static (SLS) and dynamic (DLS) light scattering. As expected, diffusion coefficients determined by PFG‐NMR spectroscopy are systematically lower than those from DLS. The PFG‐NMR measurements provided higher values of c tr e ( X )/ c tot than the model calculations, illustrating that the basic assumption used in the calculations, i.e., that the number concentration of co‐micelles in mixed solutions follows the dilution with a triblock copolymer solution, 1 − X , is not fully valid at high X (weight fraction of PS‐HPB) values.Comparison of PFG‐NMR spectroscopy and SLS ( c tr e / c tot = equilibrium concentration of free PS‐HPB‐PS over the total concentration of copolymers in solution, X = weight fraction of PS‐HPB).