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Synthesis design of polar polymers and nanostructured porous silica

Posted on:2000-03-05Degree:Ph.DType:Thesis
University:University of California, Santa BarbaraCandidate:Schmidt-Winkel, Patrick NielsFull Text:PDF
GTID:2461390014466099Subject:Polymer chemistry
Abstract/Summary:
Nanostructured and functional materials have attracted a great deal of attention because of their importance for scientific and technological progress in our society. We have proposed a novel concept for functional, polar organic polymers that is based on the ferrielectric ordering of electric dipoles along the polymer backbone. In this context, a polar odd-numbered aliphatic polysulfone and low-molecular weight model compounds possessing remarkable thermal stability, degrading at 100°C above previously prepared polysulfones, have been synthesized and characterized.;Mesoporous molecular sieves with uniform pores ranging from 2--50 nm in size are promising materials for catalysis, host-guest chemistry, separation, immobilization, encapsulation, insulation, etc. We have described a novel synthesis method to produce hierarchically ordered mesoporous silica in which the ordering on meso- to macroscopic length scales is controlled and significantly improved in one step.;In search of a simple, efficient procedure to synthesize porous materials with ultralarge mesopores (30--50 nm), we have discovered microemulsions as novel colloidal templates for mesostructured cellular foams (MCFs). MCFs represent a new class of materials with well-defined, adjustable, and continuous ultralarge mesopores (9--42 nm). The microemulsion templating route has opened up new possibilities to engineer mesoporous systems for applications such as catalyst supports where mass transport is often limited by narrow pore openings.;The microemulsion templates used to prepare MCF materials have been characterized by small-angle neutron scattering (SANS) studies. The microemulsion droplet size increases linearly with the cube root of the oil concentration, ethanol is required as cosurfactant, and the temperature behavior of the microemulsions is similar to the pure surfactant solution.;In situ SANS studies of acid-synthesized SBA-15- and MCF-type silica have shown that silica condensation is fast early in the syntheses and levels off with longer reaction time. The combination of aging and calcination under appropriate conditions is important for the formation of uniform mesopores.
Keywords/Search Tags:Materials, Polar, Silica
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