Journal Article

FZJ-2016-06898

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Molecular Exchange Kinetics of Micelles: Corona Chain Length Dependence

Zinn, T. ; Willner, L.FZJ* ; Pipich, V.FZJ* ; Richter, D.FZJ* ; Lund, R. (Corresponding author)

2016
ACS Washington, DC

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Please use a persistent id in citations: doi:10.1021/acsmacrolett.6b00395

Abstract: The rate of molecular exchange in diblock copolymer micelles is strongly dependent on the chain length of the core-forming insoluble block. Less is known about the influence of the soluble block forming the micellar corona. In this study we present a time-resolved small angle neutron scattering (TR-SANS) study exploring systematically the effect of corona chain length on the dynamics of chain exchange. As a model system we have taken amphiphilic AB diblock copolymers of the type C27H55-poly(ethylene oxide)x (C27–PEOx) with varying x between 4 and 36 kg/mol in aqueous solution in which well-defined spherical micelles with partially crystalline cores are formed. The TR-SANS results show that the chain exchange slows down considerably upon increasing PEO molecular weight, while the characteristic “attempt time” constant, τ0, was found to increase with a power law dependence τ0 ∼ MPEO9/5. The results are in excellent agreement with the Halperin and Alexander model1 and can be attributed to a reduced diffusion rate through the micellar corona. Our results clearly demonstrate that the rate for molecular exchange is not directly coupled to the solubility of the amphiphile and the critical micellar concentration, as has previously been indicated.

Keyword(s): Polymers, Soft Nano Particles and Proteins (1st) ; Chemistry (2nd) ; Soft Condensed Matter (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS (München) ; Jülich Centre for Neutron Science JCNS (München) ; JCNS-FRM-II)
2. Neutronenstreuung (Neutronenstreuung ; JCNS-1)
3. Neutronenstreuung (ICS-1)
4. Streumethoden (JCNS-2)
5. Streumethoden (PGI-4)

Research Program(s):

1. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. KWS-1: Small angle scattering diffractometer (NL3b)
2. KWS-2: Small angle scattering diffractometer (NL3ao)

Appears in the scientific report 2016

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; IF >= 5 ; JCR ; No Authors Fulltext ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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