Abstract
The thermomechanical responses of polymers, which provide limitations to their practical use, are favourably altered by the addition of trace amounts of a nanofiller. However, the resulting changes in polymer properties are poorly understood, primarily due to the non-uniform spatial distribution of nanoparticles. Here we show that the thermomechanical properties of 'polymer nanocomposites' are quantitatively equivalent to the well-documented case of planar polymer films. We quantify this equivalence by drawing a direct analogy between film thickness and an appropriate experimental interparticle spacing. We show that the changes in glass-transition temperature with decreasing interparticle spacing for two filler surface treatments are quantitatively equivalent to the corresponding thin-film data with a non-wetting and a wetting polymer-particle interface. Our results offer new insights into the role of confinement on the glass transition, and we conclude that the mere presence of regions of modified mobility in the vicinity of the particle surfaces, that is, a simple two-layer model, is insufficient to explain our results. Rather, we conjecture that the glass-transition process requires that the interphase regions surrounding different particles interact.
| Original language | English |
|---|---|
| Pages (from-to) | 693-698 |
| Number of pages | 6 |
| Journal | Nature Materials |
| Volume | 4 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 2005 |
| Externally published | Yes |
Bibliographical note
Funding Information:The authors are grateful to the National Science Foundation for funding this research through a Nanoscale Science and Engineering Center Grant. Additional funding was provided by the NSF Division of Materials Research (S.K.K.), Eastman Kodak (B.C.B., S.K.K. and L.S.S.) and the Office of Naval Research (S.K.K. and L.S.S.). The authors also thank R. Krishnamoorti, S. Granick, S. S. Sternstein, P. Keblinski, J. Forrest, M. T. Takemori and A. Eitan for discussions and comments, W. Kim for gel permeation chromatography experiments, A. Kumar for SEM images and the 2001 Mettler–Toledo Thermal Analysis Educational Grant for DSC and TGA. K.C. would like to thank the Ministry of Science and Technology of Korea (National Research Laboratory Program) for their funding. Correspondence and requests for materials should be addressed to S.K.K. or L.S.S. Supplementary Information accompanies this paper on www.nature.com/naturematerials.