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Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels.
J Phys Chem Lett. 2019 Sep 05; 10(17):5231-5236.JP

Abstract

We present the structure and dynamics of highly concentrated core-shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell suspended in water. With X-ray photon correlation spectroscopy, we are able to follow dynamical changes over the volume phase transition of PNIPAm at LCST = 32 °C. On raising the temperature beyond LCST, the structural relaxation times continue to decrease. The effect is accompanied by a transition from stretched to compressed exponential shape of the intensity autocorrelation function. Upon further heating, we find a sudden slowing down for the particles in their collapsed state. The q dependence of the relaxation time shows an anomalous change from τc ∝ q-3 to τc ∝ q-1. Small angle X-ray scattering data evidence a temperature-induced transition from repulsive to attractive forces. Our results indicate a temperature-induced phase transition from a colloidal liquid with polymer-driven dynamics toward a colloidal gel.

Authors+Show Affiliations

Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany. The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany.Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany. The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany.Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany. The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany.Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States.Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany. The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31433650

Citation

Frenzel, Lara, et al. "Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels." The Journal of Physical Chemistry Letters, vol. 10, no. 17, 2019, pp. 5231-5236.
Frenzel L, Lehmkühler F, Lokteva I, et al. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett. 2019;10(17):5231-5236.
Frenzel, L., Lehmkühler, F., Lokteva, I., Narayanan, S., Sprung, M., & Grübel, G. (2019). Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. The Journal of Physical Chemistry Letters, 10(17), 5231-5236. https://doi.org/10.1021/acs.jpclett.9b01690
Frenzel L, et al. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett. 2019 Sep 5;10(17):5231-5236. PubMed PMID: 31433650.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. AU - Frenzel,Lara, AU - Lehmkühler,Felix, AU - Lokteva,Irina, AU - Narayanan,Suresh, AU - Sprung,Michael, AU - Grübel,Gerhard, Y1 - 2019/08/23/ PY - 2019/8/23/pubmed PY - 2019/8/23/medline PY - 2019/8/22/entrez SP - 5231 EP - 5236 JF - The journal of physical chemistry letters JO - J Phys Chem Lett VL - 10 IS - 17 N2 - We present the structure and dynamics of highly concentrated core-shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell suspended in water. With X-ray photon correlation spectroscopy, we are able to follow dynamical changes over the volume phase transition of PNIPAm at LCST = 32 °C. On raising the temperature beyond LCST, the structural relaxation times continue to decrease. The effect is accompanied by a transition from stretched to compressed exponential shape of the intensity autocorrelation function. Upon further heating, we find a sudden slowing down for the particles in their collapsed state. The q dependence of the relaxation time shows an anomalous change from τc ∝ q-3 to τc ∝ q-1. Small angle X-ray scattering data evidence a temperature-induced transition from repulsive to attractive forces. Our results indicate a temperature-induced phase transition from a colloidal liquid with polymer-driven dynamics toward a colloidal gel. SN - 1948-7185 UR - https://www.unboundmedicine.com/medline/citation/31433650/Anomalous_Dynamics_of_Concentrated_Silica-PNIPAm_Nanogels L2 - https://dx.doi.org/10.1021/acs.jpclett.9b01690 DB - PRIME DP - Unbound Medicine ER -
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