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Block Copolymer Micelles with an Intermediate Star‐/Flower‐Like Structure Studied by 1 H NMR Relaxometry
Author(s) -
Weiss Jan,
Wienk Hans,
Boelens Rolf,
Laschewsky André
Publication year - 2014
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201300753
Subject(s) - copolymer , micelle , relaxometry , polymer chemistry , chemistry , relaxation (psychology) , star (game theory) , aqueous solution , spin echo , organic chemistry , polymer , magnetic resonance imaging , physics , medicine , psychology , social psychology , radiology , astrophysics
1 H NMR relaxation is used to study the self‐assembly of a double thermoresponsive diblock copolymer in dilute aqueous solution. Above the first transition temperature, at which aggregation into micellar structures is observed, the trimethylsilyl (TMS)‐labeled end group attached to the shell‐forming block shows a biphasic T 2 relaxation. The slow contribution reflects the TMS groups located at the periphery of the hydrophilic shell, in agreement with a star‐like micelle. The fast T 2 contribution corresponds to the TMS groups, which fold back toward the hydrophobic core, reflecting a flower‐like micelle. These results confirm the formation of block copolymer micelles of an intermediate nature (i.e., of partial flower‐like and star‐like character), in which a part of the TMS end groups folds back to the core due to hydrophobic interactions.