Influence of Interfacial Layer Between Nanoparticles and Polymeric Matrix on Viscoelastic Properties of Hydrogel Nanocomposites

Abstract

The viscoelastic properties of nanocomposites are influenced by both the nanoparticle distribution and the nanoparticle-polymer affinity. These two parameters are closely coupled, and evaluation of individual contributions to the mechanical properties is a critical requirement for efficient development of nanocomposites.To decouple these two effects, we utilized charge repulsion among nanoparticles so that we could essentially eliminate particle agglomeration. We then investigated how the nanoparticle-polymer affinity relates to the mechanical properties of the nanocomposite by comparing silica and polystyrene nanoparticles. The surface roughness of the particles and the molecular conformation of the interfacial layer between the polymer and the nanoparticles were characterized by synchrotron small-angle X-ray scattering and quartz crystal microbalance, respectively. On polystyrene particles, the surface roughness was larger, and the polymer adsorbed strongly. Consequently, the mobility of the adsorbed polymer was reduced compared to that on silica particles. This reduced mobility explains a smaller viscoelastic loss for the polystyrene-filled nanocomposite compared to the silicafilled nanocomposite.

Influence of dynamic crosslinking on the morphology, crystallization, and dynamic mechanical properties of PA6,12/EVA blends

“…This relationship is expressed as eq. , where Δρ is the electron density difference between the two phases: …”

“…Subsequently, the samples were cooled to 200 °C for measurements. The interfacial thickness was determined from the electronic contrast scattering of a two‐phase system, as described in the literature …”

“…The interfacial thickness was determined from the electronic contrast scattering of a two-phase system, as described in the literature. 42,43 Effect of EVA on PA6,12 Crystallization. The lamellar long period (L p ) can be estimated from the Bragg relationship [eq.…”

Reactive melt blending of PS‐POSS hybrid nanocomposites

“…For an idealized two‐phase system with a sharp interface, Porod's law states that the scattering intensity ( I id ) decreases as a function of q −4 for large q (called the Porod region), with the proportionality constant related to the surface area ( S ) of the boundaries between two phases:35, 36 …”

“…A positive deviation is caused by the background scattering from the pure individual phases, which is due to the density fluctuations within the phases arising from thermal motions of the atoms 39, 40. The negative deviation is related to the existence of a diffuse transition region between two phases 36…”