Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organizationReport as inadecuate




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Colloid and Polymer Science

, Volume 284, Issue 11, pp 1243–1254

First Online: 11 April 2006Received: 26 September 2005Accepted: 05 December 2005

Abstract

Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of polybutyl acrylate as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block polydimethylacrylamide, the strongly hydrophilic polyacryloyloxyethyl methylsulfoxide, and the thermally sensitive polyN-acryloylpyrrolidine. Aqueous micellar solutions of the block copolymers were prepared and characterized by static and dynamic light scattering analysis DLS and SLS. No critical micelle concentration could be detected. The micellization was thermodynamically favored, although kinetically slow, exhibiting a marked dependence on the preparation conditions. The polymers formed micelles with a hydrodynamic diameter from 20 to 100 nm, which were stable upon dilution. The micellar size was correlated with the composition of the block copolymers and their overall molar mass. The micelles formed with the two most hydrophilic blocks were particularly stable upon temperature cycles, whereas the thermally sensitive polyN-acryloylpyrrolidine block showed a temperature-induced precipitation. According to combined SLS and DLS analysis, the micelles exhibited an elongated shape such as rods or worms. It should be noted that the block copolymers with the most hydrophilic polysulfoxide block formed inverse micelles in certain organic solvents.

KeywordsMacrosurfactants Block copolymers Micelles Inverse micelles Sulfoxide AbbreviationsDHhydrodynamic diameter of micelles

DLSdynamic light scattering

DMSOdimethylsulfoxide

LCSTlower critical solution temperature

NMRnuclear magnetic resonance

RAFTreversible addition fragmentation chain transfer

Rggyration radius of micelles

Rhhydrodynamic radius of micelles

SLSstatic light scattering

Tgglass transition temperature

THFtetrahydrofuran

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Author: Sébastien Garnier - André Laschewsky

Source: https://link.springer.com/







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