This title appears in the Scientific Report :
2016
Please use the identifier:
http://dx.doi.org/10.1021/acsmacrolett.6b00395 in citations.
Molecular Exchange Kinetics of Micelles: Corona Chain Length Dependence
Molecular Exchange Kinetics of Micelles: Corona Chain Length Dependence
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-...
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Personal Name(s): | Zinn, Thomas |
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Willner, Lutz / Pipich, Vitaliy / Richter, Dieter / Lund, Reidar (Corresponding author) | |
Contributing Institute: |
Neutronenstreuung; ICS-1 Neutronenstreuung; JCNS-1 JCNS-FRM-II; JCNS-FRM-II Streumethoden; PGI-4 Streumethoden; JCNS-2 |
Published in: | ACS Macro Letters, 5 (2016) 7, S. 884 - 888 |
Imprint: |
Washington, DC
ACS
2016
|
DOI: |
10.1021/acsmacrolett.6b00395 |
Document Type: |
Journal Article |
Research Program: |
Jülich Centre for Neutron Research (JCNS) FRM II / MLZ |
Subject (ZB): | |
Publikationsportal JuSER |
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. |