Nanocomposites by Covalent Bonding between Inorganic Nanoparticles and Polymers
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Nanocomposites by Covalent Bonding between Inorganic Nanoparticles and Polymers Yigal D. Blum,1 Nobuyuki Kambe, D. Brent MacQueen,1 , Sujeet Kumar, Shiv Chiruvolu, and Benjamin Chaloner-Gill NanoGram Corporation 46774 Lakeview Blvd., Fremont, CA 94538, U.S.A. 1 Chemical Science and Technology Laboratory, SRI International 333 Ravenswood Ave, Menlo Park, CA 94025, U.S.A. ABSTRACT A generic approach to chemically facilitate the interactions of nanoparticles with conventional polymers is developed to address the design and processing capability of inorganicorganic nanocomposites. This approach introduces homogeneity to the composite and can be used as a tailoring tool for microstructure architecture. Nanoparticles produced by NanoGram’s technology are excellent for such nanocomposites. Their spherical shape and narrow size distribution assist in the processing of homogeneous blends. High loads of particles within a polymeric matrix can be achieved without losing homogeneity. Alternatively, the particles can be selectively attracted into desired domains. INTRODUCTION Numerous approaches for inorganic-organic hybrids are currently under development in an attempt to incorporate advantageous micro- and nanostructure designs, unique performances, and synergistic effects of the merged components [1]. Many cases involve developing the nanoparticles in situ or forming them in a solution and then mixing them with the organic phase without isolating the evolved particles [2]. With some exceptions, such as gold or other metal particles, most of the in situ developed particles are only precursors to ceramic crystalline phases. They are far from providing the anticipated functions expected from the crystalline material (e.g., colloidal silica and alumina). The incorporation of preformed nanoparticles with fully developed crystalline phases into polymeric materials is a rapidly growing field in nanotechnology [3], primarily focusing on improving toughness and hardness of elastomeric and transparent materials [4]. Optical and electronic applications are also targeted. However, it is difficult to obtain high loading of nanoparticles in polymeric materials because they tend to agglomerate or dramatically increase the polymer viscosity. Many of the currently available nanoparticles (fumed silica, for example) appear to have hard agglomeration even before they are incorporated into the organic phase. There is a need to develop a methodology to overcome these problems. A desirable capability beyond maximizing the loading of particles is to selectively target the nanoparticles into self-assembled domains. This technological achievement will open novel opportunities for photonic (and electronic) applications [5]. Incorporation of nanomaterials into polymeric media to form nanocomposites is considered a promising process to achieve tunability of wavelengths as well as fabrication of submicron-scale device structures. It will allow selective localization of nanoparticles in block copolymeric domains, which would lead to new photonic and waveg
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