Local surface mechanical properties of PDMS-silica nanocomposite probed with Intermodulation AFMShow others and affiliations
2017 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 150, p. 111-119Article in journal (Refereed) Published
Abstract [en]
The mechanical properties of polymeric nanocomposites are strongly affected by the nature of the interphase between filler and matrix, which can be controlled by means of surface chemistry. In this report, we utilize intermodulation atomic force microscopy (ImAFM) to probe local mechanical response with nanometer-scale resolution of poly(dimethylsiloxane) (PDMS) coatings with and without 20 wt% of hydrophobic silica nanoparticles. The data evaluation is carried out without inferring any contact mechanics model, and is thus model-independent. ImAFM imaging reveals a small but readily measurable inhomogeneous mechanical response of the pure PDMS surface layer. The analysis of energy dissipation measured with ImAFM showed a lowering of the viscous response due to the presence of the hydrophobic silica nanoparticles in the polymer matrix. An enhanced elastic response was also evident from the in-phase stiffness of the matrix, which was found to increase by a factor of 1.5 in presence of the nanoparticles. Analysis of dissipation energy and stiffness in the immediate vicinity of the nanoparticles provides an estimate of the interphase thickness. Because the local stiffness varies significantly near the nanoparticle, AFM height images contain artifacts that must be corrected in order to reveal the true surface topography. Without such a correction the AFM height images erroneously show that the stiff particles protrude from the surface, whereas corrected images show that they are actually embedded in the matrix and likely covered with a thin layer of polymer.
Place, publisher, year, edition, pages
2017. Vol. 150, p. 111-119
Keywords [en]
Atomic force microscopy, Intermodulation, Interphase, Nanocomposites, Nanomechanical properties, Deformation, Energy dissipation, Hydrophobicity, Mechanical properties, Microchannels, Nanoparticles, Silica, Stiffness, Stiffness matrix, Surface chemistry, Surface topography, Interphase thickness, Nanomechanical property, Nanometer-scale resolution, Polydimethylsiloxane PDMS, Polymeric nanocomposites, Silica nanocomposites, Silica nanoparticles, Polymer matrix composites
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-30800DOI: 10.1016/j.compscitech.2017.07.013Scopus ID: 2-s2.0-85025104154OAI: oai:DiVA.org:ri-30800DiVA, id: diva2:1138732
Note
Funding details: CSC, China Scholarship Council; Funding details: Knut och Alice Wallenbergs Stiftelse; Funding details: VR, Vetenskapsrådet; Funding text: PMC acknowledges financial support from the Swedish Research Council (VR). HH acknowledges a stipend from the China Scholarship Council. DBH acknowledges support from the Olle Enqvist Foundation. Both PMC and DBH acknowledge support and equipment donated by the Knut and Alice Wallenberg Foundation.
2017-09-062017-09-062023-03-30Bibliographically approved