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Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels.
J Phys Chem Lett 2019; :5231-5236JP

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, 2019, pp. 5231-5236.
Frenzel L, Lehmkühler F, Lokteva I, et al. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett. 2019.
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, pp. 5231-5236. doi:10.1021/acs.jpclett.9b01690.
Frenzel L, et al. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett. 2019 Aug 23;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 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 -