Design of polymer brush on size-controlled metal nanoparticles for surfactants and catalysts

Abstract

Polymer brushes have been used for assemblies of macromolecules which are tethered to the surface that possess proper chemical and physical properties. For nanoparticle surfaces, the polymer brushes are typically bound through covalent attachment or physical adsorption. When the materials with heterogeneous structure are formed from combining different components, their properties may rely on the characteristics of the com-ponents and the degree of dispersion. Here, we developed a model system of polymer coated metal nanoparti-cles with controlled sizes or aspect ratios and a uniform size distribution and employed these nanoparticles for two application fields, such as compatibilizers and catalysts. Incorporation of nanoparticles in polymer matrices is a field of particular interest for materials engineering and the study of nanoparticle-matrix interaction. A desirable approach would involve the blendind of pre-made nanoparticles into pre-synthesized polymer. The precise control of the particles at the interface exhibits surfactant-like properties, and thus this approach for compatibilizers to locate nanoparticles at the interface in the immiscible polymer blended system can be successfully carried out by tuning the surface properties of nanoparticles with attachment of the polymer ligands to their surface. We prepared polytriphenylamine (PTPA) whose derivatives have useful properties in electrical conductivity and electroluminescence, and they are used as hole transporting materials (HTMs) in dye-sensitized solar cells (DSSCs) and organic light-emitting diodes (OLEDs). To study the efficiency of the polymer coated metal nanoparticles on compatibility, we compared PS/PTPA blends stabilized by size controlled gold nanoparticles (Au NPs) and aspect ratio con-trolled CuPt nanorods (CuPt NRs) to those stabilized by PS-b-PTPA block copolymer as conventional com-patibilizers, and thus former stabilized blends showed better miscibility of polymer blend than PS-b-PTPA...