Issue 6, 2012

Synthesis by nitroxide-mediated aqueous dispersion polymerization, characterization, and physical core-crosslinking of pH- and thermoresponsive dynamic diblock copolymer micelles

Abstract

Diblock copolymers consisting of a poly(acrylic acid) (PAA) segment and a LCST-type poly(N,N-diethylacrylamide) (PDEAAm) block were obtained by nitroxide-mediated polymerization in aqueous dispersion using a water-soluble macroalkoxyamine. The influence of several parameters on the polymerization (temperature, initial free nitroxide or macroalkoxyamine concentrations, and solids content) was evaluated in terms of kinetics, macromolecular control, and colloidal features. As determined by dynamic light scattering (DLS), stable dispersions of monodisperse particles could be obtained for solids content as high as 39 wt% without the need for any additional surfactant via a polymerization-induced self-assembly mechanism. Rendered possible by the use of a controlled/living polymerization process, the effective semi-batch incorporation of hydrophobic units (styrene) in the growing chains during the polymerization allowed the formation of physically crosslinked nanogels. The pH and temperature sensitivity were proved by means of DLS and high-sensitivity differential scanning calorimetry (HSDSC) measurements. Due to the formation of aggregates observed by size-exclusion chromatography in N,N-dimethylformamide, accurate molar masses could not be determined directly but deconvoluted hydrodynamic volume distributions suggested a good control of the polymerization.

Graphical abstract: Synthesis by nitroxide-mediated aqueous dispersion polymerization, characterization, and physical core-crosslinking of pH- and thermoresponsive dynamic diblock copolymer micelles

Supplementary files

Article information

Article type
Paper
Submitted
15 Feb 2012
Accepted
15 Mar 2012
First published
17 Apr 2012

Polym. Chem., 2012,3, 1526-1538

Synthesis by nitroxide-mediated aqueous dispersion polymerization, characterization, and physical core-crosslinking of pH- and thermoresponsive dynamic diblock copolymer micelles

G. Delaittre, M. Save, M. Gaborieau, P. Castignolles, J. Rieger and B. Charleux, Polym. Chem., 2012, 3, 1526 DOI: 10.1039/C2PY20084H

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