The structure of chain end-grafted nanoparticle/homopolymer nanocomposites
- 27 May 2011
- journal article
- highlight
- Published by Royal Society of Chemistry (RSC) in Soft Matter
- Vol. 7 (18), 7914-7926
- https://doi.org/10.1039/c1sm05076a
Abstract
The morphological structure of mixtures of homopolymers with inorganic nanoparticles, onto which polymer chain ends are grafted, is described herein. In the bulk, at very low grafting densities, Σ, the morphology of these polymer nanocomposites (PNCs) is largely determined by the attractive enthalpic interactions between the nanoparticle cores, mediated by entropic interactions with the grafted polymer chains. These competing interactions have been shown to be responsible for the anisotropic organization of the nanoparticles within polymer hosts. At high grafting densities, however, even in cases where the host chains and the grafted chains are of identical chemical structure, the entropic brush layer/free host chain interactions are dominant, leading to miscibility (isotropic dispersion of the nanoparticles within the polymer host) or to microscopic and macroscopic phase separation. In the limit of very small nanoparticles, radii R ≈ 1 nm, the brush/melt interactions are not important yet the nanoparticles exhibit a high tendency toward miscibility within homopolymer hosts. This paper begins with a discussion of the bulk morphology of PNCs in order to provide a context for the subsequent description of the morphological structure of thin film brush coated nanoparticle–homopolymer mixtures. A fundamental difference between these bulk and thin film PNCs is that a preferential attraction of grafted nanoparticles to interfaces renders thin film PNCs thermodynamically less stable than their bulk analogs. Morphological phase diagrams, which delineate regimes where the PNCs are miscible, incompatible or partially miscible, are parameterized in terms of the nanoparticle curvature, the chain grafting density, the grafting chain degree of polymerization, N, that of the free host chains, P, and the thermodynamic (Flory–Huggins) interaction parameter, χ, between the host and grafted chains.Keywords
This publication has 74 references indexed in Scilit:
- End grafted polymernanoparticles in a polymeric matrix: Effect of coverage and curvatureSoft Matter, 2010
- Current issues in research on structure–property relationships in polymer nanocompositesPolymer, 2010
- Expanded chain dimensions in polymer melts with nanoparticle fillersThe Journal of Chemical Physics, 2010
- Phase Behavior of Thin Film Brush-Coated Nanoparticles/Homopolymer MixturesMacromolecules, 2010
- Molecular theories of polymer nanocompositesCurrent Opinion in Solid State and Materials Science, 2009
- The pervasive chemistry of metal–organic frameworksChemical Society Reviews, 2009
- Anisotropic self-assembly of spherical polymer-grafted nanoparticlesNature Materials, 2009
- Effect of Polymer Nanoparticle Formation on the Efficiency of Polythiophene Based “Bulk-Heterojunction” Solar CellsThe Journal of Physical Chemistry C, 2008
- Polymer Nanocomposites: The “Nano” Effect on Mechanical PropertiesPolymer Reviews, 2007
- Functional inorganic nanofillers for transparent polymersChemical Society Reviews, 2007