(A) study on the synthesis and application of nano-structured materials by using polystyrene beads

Abstract

Polystyrene is one of the most widely used polymers among all industrial fields, because it offers many advantages such as low impact resistance, fair strength and stiffness, high chemical resistance, transparency, affordability, and easy of processing. In particular, polystyrenic beads with spherical form have many potentially useful characteristics through control of their diameter (or polymerization technique), degree of crosslinking, surface chemistry, porosity, etc. As such, they have a great applicable potential in a variety of industrial fields. They have been used as support of noble metal catalysts or expensive reagents, ion exchange resins, solid acid catalysts, adsorbents for organic compounds in gases or wastewater, and packing materials of chromatography. Recently, polystyrene beads have also been used for the synthesis of peptides in combinatorial chemistry, drug delivery systems, and the synthesis of nano-structured inorganic materials as templating materials. Materials with bimodal porosity have attracted considerable interest for applications in catalysis and separation because they offer multiple benefits arising from each pore size regime. For example, micro-and meso-pores may provide size- or shape-selectivity for guest molecules, while the presence of additional macropores can offer easier transport and access to active sites that should improve reaction efficiencies and minimize channel blocking. In this thesis, the polystyrenic resin beads with a bimodal pore size distribution of micropores and macropores were synthesized by chemical modification of conventional polymer beads and their adsorption behaviors were investigated for the removal of phenolic compounds in an aqueous solution. Also, biporous silicates were synthesized by combining conventional mesoporous materials synthesis methods with colloidal crystal templating and a new and simple method for preparation of silicates having bimodal porosity is suggested for mass production. ...