Herstellungs- und Alterungseffekte in Nanokompositen auf Basis von PEO
Final Report Abstract
In this project, we proposed to investigate the formation and the preparation- and agingdependent properties of adsorbed and possibly grafted polymeric interphases in the strongly interacting case of polyethyleneoxide (PEO) on spherical silica nanoparticles in bulk and aqueous suspension. The PEO in the interphase, forming an adsorption (Guiselin) brush, ultimately determines the interactions of the particles among each other and with other components of the studied system. The main results were first, that the amount of the most immobilized interfacial components, and with it the particle arrangement (and thus mechanical reinforcement) could be controlled by choice of the solvent used only during preparation (water vs. ethanol). After its publication, we however found that the results could at least partially be due to an unexpected binding reaction of the ethanol to the particle surface; a clarification is still ongoing. Second, the particle arrangement could also be tuned by initial surface modification using short functionalized PEO chains. These prevent bridge formation in composites with longer PEO chains, but can also drive particle aggregation through autophobic dewetting. Third, and as yet unpublished, we found a surprisingly large effect of particle size (interfacial curvature) on the amount of immobilized PEO. The interphase in PEO-silica composites is peculiar in a sense that its size is nearly temperature-independent and features fast but strongly anisotropic mobility. This could be reinforced by comparing this system to other nanocomposite materials, namely PEO confined between clay sheets and another polymer (P2VP) adsorbed to spherical silica particles, showing qualitatively different behavior. Finally, we used the proton spin diffusing effect to confirm that interfacial layers are dynamically heterogeneous and feature nanometer-sized domains of different dynamics coexisting also in the lateral direction.
Publications
- Reduced-mobility layers with high internal mobility in poly(ethylene oxide)–silica nanocomposites. J. Chem. Phys. 146, 203303 (2017)
Y. Golitsyn, G. J. Schneider and K. Saalwächter
(See online at https://doi.org/10.1063/1.4974768) - Initial Solvent-Driven Nonequilibrium Effect on Structure, Properties, and Dynamics of Polymer Nanocomposites. Phys. Rev. Lett. 123, 167801 (2019)
S. M. Oh, M. Abbasi, T. J. Shin, K. Saalwächter, S. Y. Kim
(See online at https://doi.org/10.1103/physrevlett.123.167801) - Control of Particle Dispersion with Autophobic Dewetting in Polymer Nanocomposites. Macromolecules 53, 4836 (2020)
N. K. Kwon, H. Kim, T. J. Shin, K. Saalwächter, J. Park, S. Y. Kim
(See online at https://doi.org/10.1021/acs.macromol.0c00190) - Structure, Mechanical Properties, and Dynamics of Polyethylenoxide/Nanoclay Nacre-Mimetic Nanocomposites. Macromolecules 53, 1716 (2020)
A. Eckert, M. Abbasi, T. Mang, K. Saalwächter, A. Walther
(See online at https://doi.org/10.1021/acs.macromol.9b01931) - Dynamic Heterogeneity of Filler-Associated Interphases in Polymer Nanocomposites. Macromol. Rapid Commun. 41, 2100061 (2021)
H. Schneider, M. Roos, Y. Golitsyn, K. Steiner, K. Saalwächter
(See online at https://doi.org/10.1002/marc.202100061) - On the Immobilized Polymer Fraction in Attractive Nanocomposites: Tg Gradient versus Interfacial Layer. Macromolecules 54, 10289 (2021)
C. Fernández-de-Alba, A. M. Jimenez, M. Abbasi, S. K. Kumar, K. Saalwächter, G. P. Baeza
(See online at https://doi.org/10.1021/acs.macromol.1c01135)
