Review of the proton exchange membranes for fuel cell applications

The sol-gel process, with its associated mild conditions, offers a new approach to the synthesis of composite materials with domain sizes approaching the molecular level. Transparent organic-inorganic composites can be prepared by dissolving preformed polymers into sol-gel precursor solutions, and then allowing the tetraalkyi orthosilicates to hydrolyze and condense to form glassy SiO, phases of different morphological structures. Alternatively, both the organic and inorganic phases can be simultaneously formed through the synchronous polymerization of the organic monomer and the sol-gel precursors. Depending upon such factors as the structures of the organic and inorganic components, the phase morphology, the degree of interpenetration, and the presence of covalent bonds between the phases, the properties of these composites can vary greatly and range from elastomeric rubbers to high-modulus materials.

Hybrid nanocomposite materials―between inorganic glasses and organic polymers

Organic/inorganic hybrid materials prepared by the sol−gel approach have rapidly become a fascinating new field of research in materials science. The explosion of activity in this area in the past decade has made tremendous progress in both the fundamental understanding of the sol−gel process and the development and applications of new organic/inorganic hybrid materials. In this review, a brief summary of the research activities in the field of organic/inorganic nanocomposite materials and a general background of the sol−gel chemistry are first given. The emphasis of this report, however, is placed on the synthesis, structure−property response, and potential applications of the organic/inorganic hybrid networks that possess chemical bonding between the organic and inorganic phases, particularly those systems that were developed in our laboratory since 1985.

Organic/Inorganic Hybrid Network Materials by the Sol−Gel Approach

A multi-core model, i.e. a simplified term of a multi-layered core model, is proposed as a working hypothesis to understand various properties and phenomena that polymer nanocomposites exhibit as dielectrics and electrical insulation. It gives fine structures to what are called "interaction zones". An interfacial layer of several tens nm is multi-layered, which consists of a bonded layer, a bound layer, and a loose layer. In addition, the Gouy-Chapman diffuse layer with the Debye shielding length of several tens to 100 nm is superimposed in the interfacial layer to cause a far-field effect. Nano-particles may interact electrically with the nearest neighbors each other due to this effect, resulting in possible collaborative effect. Such a multi-core model with the far-field effect is discussed, for example, to explain partial discharge (PD) resistance of polyamide layered silicate nanocomposites, and is verified to demonstrate its effectiveness.

Proposal of a multi-core model for polymer nanocomposite dielectrics

Development of ionomer membranes for fuel cells

Structure-property behaviour of hybrid materials incorporating tetraethoxysilane with multifunctional poly(tetramethylene oxide)

Nanocomposites were produced via sol–gel reactions for tetraethylorthosilicate within the cluster morphology of perfluorosulfonic acid films. Small-angle x-ray scattering revealed that the polar/nonpolar nanophase-separated morphological template persists despite invasion by the silicon oxide phase. Scanning electron microscopy (ESEM–EDAX) studies have indicated that the greatest silicon oxide concentration occurs near the surface and decreases to a minimum in the middle. Optical and ESEM micrographs revealed a brittle, surface-attached silica layer at high silicon oxide contents. © 1995 John Wiley & Sons, Inc.

Microstructural evolution of a silicon oxide phase in a perfluorosulfonic acid ionomer by an in situ sol-gel reaction

Novel transparent hybrid materials incorporating triethoxysilane endcapped poly(tetramethylene oxide) with tetramethoxysilane have been successfully prepared by a sol-gel process. The molecular weight of PTMO has been varied to study its effect on the structure-property behavior of these hybrid materials. Mechanical properties and dynamic mechanical behavior have been measured; small angle X-ray scattering (SAXS) has been utilized to obtain structural information. Based on the experimental results, a simplified morphological model has been suggested to describe these new hybrid systems.

Structure-property behavior of new hybrid materials incorporating oligomeric poly(tetramethylene oxide) with inorganic silicates by a sol-gel process

Physical structure of polysilicate particles in organic media

The effects of different plasticizers on the structural features of PVC were investigated. Particular emphasis was on the fine structure as denoted by small-angle X-ray scattering (SAXS). The influence of plasticizer content on the mechanical response was followed by dynamic mechanical spectroscopy. The particular plasticizers investigated principally were diethylhexyl succinate and dibutyl phthalate, although other phthalate plasticizers were investigated including dibutyl succinate and dibutyl sebacate. It was noted that structural features at the 100– to 200–a level were systematically influenced by the type and amount of plasticizer and in particular by its solubility parameter. To account for the observed behavior, a model was proposed which speculates that the absorption of plasticizer is nonuniform within the system and in particular within the local regions where crystallites exist. The level of swelling of plasticizer into the amorphous regions at some distance from the crystallites is d...

Hao-Hsin Huang

Papers

Structure-property behaviour of hybrid materials incorporating tetraethoxysilane with multifunctional poly(tetramethylene oxide)

Microstructural evolution of a silicon oxide phase in a perfluorosulfonic acid ionomer by an in situ sol-gel reaction

Structure-property behavior of new hybrid materials incorporating oligomeric poly(tetramethylene oxide) with inorganic silicates by a sol-gel process

Physical structure of polysilicate particles in organic media

A morphological study on the plasticization of poly(vinyl chloride) by diethylhexyl succinate and Dibutyl Phthalate