Figg, C. Adrian, Simula, Alexandre, Gebre, Kalkidan A., Tucker, Bryan S., Haddleton, David M. and Sumerlin, Brent S. (2015) Polymerization-induced thermal self-assembly (PITSA). Chemical Science, 6 (2). pp. 1230-1236. doi:10.1039/c4sc03334e ISSN 2041-6520.

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Abstract

Polymerization-induced self-assembly (PISA) is a versatile technique to achieve a wide range of polymeric nanoparticle morphologies. Most previous examples of self-assembled soft nanoparticle synthesis by PISA rely on a growing solvophobic polymer block that leads to changes in nanoparticle architecture during polymerization in a selective solvent. However, synthesis of block copolymers with a growing stimuli-responsive block to form various nanoparticle shapes has yet to be reported. This new concept using thermoresponsive polymers is termed polymerization-induced thermal self-assembly (PITSA). A reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide from a hydrophilic chain transfer agent composed of N,N-dimethylacrylamide and acrylic acid was carried out in water above the known lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAm). After reaching a certain chain length, the growing PNIPAm self-assembled, as induced by the LCST, into block copolymer aggregates within which dispersion polymerization continued. To characterize the nanoparticles at ambient temperatures without their dissolution, the particles were crosslinked immediately following polymerization at elevated temperatures via the reaction of the acid groups with a diamine in the presence of a carbodiimide. Size exclusion chromatography was used to evaluate the unimer molecular weight distributions and reaction kinetics. Dynamic light scattering and transmission electron microscopy provided insight into the size and morphologies of the nanoparticles. The resulting block copolymers formed polymeric nanoparticles with a range of morphologies (e.g., micelles, worms, and vesicles), which were a function of the PNIPAm block length.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Divisions:	Faculty of Science, Engineering and Medicine > Science > Chemistry
Library of Congress Subject Headings (LCSH):	Self-assembly (Chemistry), Polymerization
Journal or Publication Title:	Chemical Science
Publisher:	Royal Society of Chemistry
ISSN:	2041-6520
Official Date:	1 February 2015
Dates:	Date Event 1 February 2015 Published 14 November 2014 Available 14 November 2014 Accepted 30 October 2014 Submitted
Volume:	6
Number:	2
Number of Pages:	7
Page Range:	pp. 1230-1236
DOI:	10.1039/c4sc03334e
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Open Access (Creative Commons)
Date of first compliant deposit:	7 December 2015
Date of first compliant Open Access:	7 December 2015
Funder:	National Science Foundation (U.S.) (NSF), Royal Society (Great Britain)
Grant number:	HRD-1249202 (NSF), DMR-1410223 (NSF)

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