One‐Pot Preparation of Conducting Polymer‐Coated Silica Particles: Model Highly Absorbing Aerosols

Abstract

Near‐monodisperse 0.50 μm and 1.0 μm silica particles are surface‐modified using 3‐(trimethoxysilyl)propyl methacrylate (MPS) and subsequently coated by aqueous deposition of an ultrathin polypyrrole (PPy) overlayer to produce PPy‐coated silica particles. The targeted degree of MPS modification and PPy mass loading are systematically varied to optimize the colloidal stability and PPy coating uniformity. MPS surface modification is characterized by contact angle goniometry and the PPy overlayer uniformity is assessed by scanning electron microscopy. HF etching of the silica cores produces hollow PPy shells, thus confirming the contiguous nature of the PPy overlayer and the core–shell morphology of the original particles. Four‐point probe measurements and XPS studies indicate that the electrical conductivity of pressed pellets of PPy‐coated silica particles increases with PPy surface coverage. Colloidal stabilities of the bare, MPS‐modified, and PPy‐coated silica particles in aqueous solution are assessed using disk centrifuge photosedimentometry. MPS surface modification results in weak flocculation, with subsequent PPy deposition causing further aggregation. In contrast, white light aerosol spectrometry indicates a relatively high degree of dispersion for PPy‐coated silica particles in the gas phase. Such PPy‐coated silica particles are expected to be useful mimics for silica‐rich micrometeorites and may also serve as a model highly absorbing aerosol.

Occlusion of Sulfate-Based Diblock Copolymer Nanoparticles within Calcite: Effect of Varying the Surface Density of Anionic Stabilizer Chains

“…XPS has excellent inter-element resolution and is highly surface-specific, with a typical sampling depth of 2–10 nm. 56 For the current study, the PSEM stabilizer chains provide a unique source of sulfur atoms. Hence higher sulfur contents indicate higher stabilizer surface densities (see Figure 5 ).…”

Space science applications for conducting polymer particles: synthetic mimics for cosmic dust and micrometeorites

“…59 This problem has been recently addressed by surface modification of near-monodisperse silica particles of approximately 1 mm diameter using a commercial organosilane reagent, 3-(methacryloyl)propyl triethoxysilane. 57 This increases the surface wettability of the silica particles and hence enables much more uniform deposition of the polypyrrole overlayer, as judged by scanning electron microscopy (see Fig. 8).…”

Promoting the dispersibility of silica and interfacial strength of rubber/silica composites prepared by latex compounding

“…Firstly, it is of significance to modify silica to improve its dispersibility in the rubber matrix, and many related studies have been conducted. [15][16][17][18][19][20] For example, silica modified by silane coupling agents, [21][22][23][24][25][26] surfactant, [27][28][29][30] both silane coupling agents and surfactant, [31] grafting polymer, [32,33] adding other fillers, [34][35][36] ionic liquid. [37] What's more, mechanical force can also improve the dispersibility of silica, but it has little effect on the enhancement of interface strength due to the bad compatibility of silica and rubber.…”