Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

Structural engineering of polyurethane coatings for high performance applications

Concepts for the incorporation of inorganic building blocks into organic polymers on a nanoscale

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

Organic-inorganic hybrids appear as a creative alternative for obtaining new materials with unusual features. This is related to their diphasic structures, leading to multifunctional materials. The low-temperature processes which are used to synthesize such structures provide a wide versatility in the design of the compounds. The potentiality of the chemistry is to play on the structure of these mixtures and dissociate the various contributions in tailoring both phases and controlling the interfaces. In this paper, a review of some chemistry pathways to hybrid materials is presented. The nature of the bonds between organic and inorganic phases is used to divide them in two major families: class I corresponds to materials with weak interphase bonding, while class II corresponds to materials where both phases are chemically grafted. Applications of these materials in the fields of optics, iono-electronics, mechanics, biology and others are expected. Some applications are reviewed, with respect to the versatility of the synthetic procedure. Most of the properties of these new high-technology materials are dependent on their structural and chemical composition as well as on the dynamical properties inside the blends.

Hybrid organic–inorganic materials: a land of multidisciplinarity

In situ polymerization of tetraethoxysilane in polymers: chemical nature of the interactions

In situ polymerization of tetraethoxysilane in poly(methyl methacrylate): morphology and dynamic mechanical properties

Composites of poly(vinylacetate) (PVAc) and silica were prepered from the in situ polymerization of acid-catalyzed tetraethoxysilane. The physical properties of these composites were compared with those of PVAc/fumed silica (of 7-nm nominal perticle size) composites prepered by both melt-milling and solution-casting from THF or CCl 4 . Their morphologies were examined by TEM and SAXS revealing that, although all the materials were optically transparent, differences in the primery perticle size and interfacial regions exist. IR data showed that substantially more hydrogen bonding occurs in the in situ prepared composites.

Poly(vinyl acetate)/silica-filled materials: material properties of in situ vs fumed silica particles

In-situ polymerization of silicon alkoxide was used to prepare composites of silicon dioxide and poly(vinyl acetate) (PVAc). The FTIR, dielectric, and dynamic mechanical spectroscopy results showed that β decreased with increasing sol-gel concentration, indicating that there is a broadening in the distribution of relaxation times for PVAc chains. The results suggested that thereexists an interfacial region in the composidtes where the mobility of the PVAc is reduced by the interactions with the silicate network.

Christine J. T. Landry

Papers

In situ polymerization of tetraethoxysilane in polymers: chemical nature of the interactions

In situ polymerization of tetraethoxysilane in poly(methyl methacrylate): morphology and dynamic mechanical properties

Poly(vinyl acetate)/silica-filled materials: material properties of in situ vs fumed silica particles

Dynamic studies of the molecular relaxations and interactions in microcomposites prepared by in-situ polymerization of silicon alkoxides

Role of trialkoxysilane functionalization in the preparation of organic-inorganic composites