1 research outputs found
Soft Nanocompositesî—¸From Interface Control to Interphase Formation
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 polyÂ(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