Kinetic processes at the demixing transition of PNIPAM solutions

Philipp, Martine; Müller, Ulrich; Jiménez Riobóo; Sanctuary, Roland; Müller-Buschbaum, P.; Krüger, Jan-Kristian

doi:10.1039/c3sm51333e

Reference : Kinetic processes at the demixing transition of PNIPAM solutions


	Document type :	Scientific journals : Article
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Physics
	To cite this reference:	http://hdl.handle.net/10993/13345

Title :	Kinetic processes at the demixing transition of PNIPAM solutions
Language :	English
Author, co-author :	Philipp, Martine [Technische Universität München - TUM]
	Müller, Ulrich [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit >]
	Jiménez Riobóo [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit > ; Instituto de Ciencia de Materiales de Madrid, CSIC]
	Sanctuary, Roland [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit >]
	Müller-Buschbaum, P. [Technische Universität München - TUM]
	Krüger, Jan-Kristian [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit >]
Publication date :	2013
Journal title :	Soft Matter
Publisher :	Royal Society of Chemistry
Volume :	9
Pages :	887–9896
Peer reviewed :	Yes (verified by ORBi^lu)
Audience :	International
ISSN :	1744-683X
e-ISSN :	1744-6848
City :	Cambridge
Country :	United Kingdom
Abstract :	[en] Kinetic processes, which are joined with mass transport, are studied in the vicinity of the sharp LCST-type demixing transition of semi-dilute aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions. These processes are slow as compared to the highly cooperative collapse of individual polymer chains. Purely elastic properties, that are particularly sensitive to this phase transition, are addressed depending on the temperature, space and time by Brillouin spectroscopy. Above the demixing temperature Tc, we discriminate between kinetics related to the phase separation into PNIPAM-rich and PNIPAM-poor domains and kinetics connected to the impact of gravitation on the on-going phase separation. Using shallow temperature jumps of 0.3 C, the growth of compact PNIPAM-rich agglomerates with identical gel-like mechanical consistency is provoked independently of temperature and position within the sample above Tc. Astonishingly, the transition temperature does not vary while heating or cooling the solutions across the phase transition, although the elastic properties depend strongly on space and time during the equilibration of PNIPAM concentration gradients following the re-entrance into the lowtemperature phase.
Permalink :	http://hdl.handle.net/10993/13345
DOI :	10.1039/c3sm51333e
Other URL :	www.rsc.org/softmatter

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