Deswelling microgel particles using hydrostatic pressure
- Lietor-Santos, Juan-Jose School of Physics, Georgia Institute of Technology, Atlanta, USA
- Sierra-Martin, Benjamin School of Physics, Georgia Institute of Technology, Atlanta, USA
- Vavrin, Ronny Laboratory for Neutron Scattering, ETH Zurich - Paul Scherrer Institute, Villigen, Switzerland
- Hu, Zhibing University of North Texas, Denton, Texas, USA
- Gasser, Urs Laboratory for Neutron Scattering, ETH Zurich - Paul Scherrer Institute, Villigen, Switzerland - Adolphe Merkle Institut, University of Fribourg, Switzerland
- Fernandez-Nieves, Alberto School of Physics, Georgia Institute of Technology, Atlanta, USA
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09.07.2009
Published in:
- Macromolecules. - 2009, vol. 42, no. 16, p. 6225–6230
English
We report on the use of hydrostatic pressure, P, to deswell thermosensitive poly(N-isopropylacrylamide) (pNIPAM) microgels and show that it can affect the polymer−solvent mixing as much as temperature, which is the traditional variable used to deswell pNIPAM particles. Interestingly, the microgel volume changes more gradually with pressure than it does with temperature. By comparing the pressure and temperature induced deswelling, we obtain the pressure dependence of the Flory solvency parameter, χ; it increases with P, indicating that pressure decreases the polymer−solvent miscibility. We interpret this increase in terms of the entropy change, S, when a polymer−solvent contact is broken to form a solvent−solvent contact and find that |S| also increases with P, consistent with previous experimental results with polymers and other gels. Hydrostatic pressure thus changes the entropic contribution of mixing, causing χ to increase and ultimately leading to particle deswelling.
- Faculty
- Faculté des sciences et de médecine
- Department
- AMI - Soft Nanoscience
- Language
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- English
- Classification
- Physics
- License
- License undefined
- Identifiers
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- RERO DOC 13228
- DOI 10.1021/ma9010654
- Persistent URL
- https://folia.unifr.ch/unifr/documents/301293
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