Development of Filler Structure in Colloidal Silica–Polymer Nanocomposites

Abstract

The realization of the full potential for polymeric nanocomposites to manifest their entitled property improvements relies, for some properties, on the ability to achieve maximum particle–matrix interfacial area. Well-dispersed nanocomposites incorporating colloidal silica as the filler can be realized in both polystyrene and poly(methyl methacrylate) matrices by exploiting the charge stabilized nature of silica in nonaqueous solvents which act as Bronsted bases. We demonstrate that dispersions of colloidal silica in dimethylformamide are charge stabilized, regardless of organosilyl surface functionalization. When formulated with polymer solutions, the charge stabilized structure is maintained during drying until the charged double layer collapses. Although particles are free to diffuse and cluster after this neutralization, increased matrix viscosity retards the kinetics. We demonstrate how high molecular weight polymers assist in immobilizing the structure of the silica to produce well-dispersed composites. The glass transition temperatures of these composites do not vary, even at loadings up to 50 vol %.

Simultaneous Phase Transfer and Surface Modification of TiO2 Nanoparticles Using Alkylphosphonic Acids: Optimization and Structure of the Organosols

“…The maximum contrast of the layer is fixed to that of the phosphonic acids, with a prefactor accounting for solvation, that is, a reduced layer density. If we define φ as the volume fraction of PA in the shell, the remaining fraction (1 − φ) being occupied by the solvent of scattering length density ρ s (i.e., either ρ H or ρ D ), then the average scattering length density of the shell reads ρ ρ φ ρ ρ = + − ( ) shell s grafts s (1) and obviously the shell contrast reduces to Δρ shell = φ(ρ grafts − ρ s ). Several conclusions can be drawn from the quantitative analysis of the data in Figure 5a using this core−shell model.…”

Dielectric performance of high permitivity nanocomposites: impact of polystyrene grafting on BaTiO3 and TiO2

“…At these intermediate to high loading levels, achieving good nanoparticle dispersion -especially in non-polar polymer matrices -is challenging due particle agglomeration during film preparation. 4 Field intensification in the matrix phase, along with extended filler clusters, reduce E BD and enhance charge migration along the interfaces of the percolated fillers. This leads to a decrease in E BD as filler is added to increase ε r .…”

Short-Time Glassy Dynamics in Viscous Protein Solutions with Competing Interactions

“…[1][2][3][4][5][6] The combination of a long-ranged repulsion with a short-ranged attraction has been demonstrated to cause the formation of equilibrium cluster fluids. [1,4,[7][8][9][10][11] While clusters in SALR systems have been observed in systems of nanoparticles in polymer composites [12] and solutions with polymer depletants [1,7] as well as membrane proteins, [13] recent work has associated cluster formation with large viscosities in highly concentrated lysozyme [11] and monoclonal antibody [14] formulations, making these types of interactions relevant to the biopharmaceutical industry.…”