title: Soft Nanocomposites--From Interface Control to Interphase Formation.
abstract: We report measurements of structure, mechanical properties, glass transition temperature, and contact angle of a novel nanocomposite material consisting of swellable silsesquioxane nanoparticles with grafted poly(ethyl methacrylate) (PEMA) brushes and PEMA matrices with varying molecular weight. We measured the interparticle distance at the surface of the composites using scanning probe microscopy (SPM) and in the bulk of ∼0.5 μm thick films by grazing incidence small angle X-ray scattering (GISAXS). For a given molecular weight of the brush unstable dispersions at high molecular weight of the matrix indicate an intrinsic incompatibility between polymer-grafted-nanoparticles and homopolymer matrices. This incompatibility is affirmed by a high contact angle between the polymer-grafted-nanoparticles and the high molecular weight matrix as measured by SPM. For unstable dispersions, we measured a decreased glass transition temperature along with a decreased plateau modulus by dynamic mechanical thermal analysis (DMTA) which indicates the formation of a liquid-like layer at the brush-matrix interface. This proves the ability to decouple the structural and mechanical properties from the potential to be swollen with small molecules. It opens a new area of use of these soft nanocomposites as slow release materials with tailored mechanical properties.
authors: †Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors: Sascha A
authors: SA
authors: Pihan
authors: †Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors: Sebastian G J
authors: SG
authors: Emmerling
authors: †Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors: Hans-Jürgen
authors: HJ
authors: Butt
authors: †Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors: Rüdiger
authors: R
authors: Berger
authors: †Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.|‡Johannes Gutenberg Universität Mainz, Saarstrasse 21, D-55128 Mainz, Germany.
authors: Jochen S
authors: JS
authors: Gutmann
keywords: GISAXS; glass transition temperature; mechanical properties; nanocomposite; polymer brushes; scanning force microscopy