Multiphasic nanostructured composites

Multifunctional materials will play an important role in the development of Photonics Technology. This paper describes novel multifunctional polymeric composites for applications in both active and passive photonic components. On the molecular level, we have introduced multifunctionality by design and synthesis of chromophores which by themselves exhibit more than one functionality. At the bulk level, we have introduced the concept of a multiphasic nanostructured composites where phase separation is controlled in the nanometer range to produce optically transparent bulk in which each domain produces a specific photonic function. Results are presented from the studies of up-converted two-photon lasing, two-photon confocal microscopy, optical power limiting, photorefractivity and optical channel waveguides to illustrate the application of the multifunctional optical composites. 

Multiphasic Nanostructured Composites Bulks. A novel approach to produce multifunctional polymeric composites is to use a multiphase system with the phase separation at the nanometer scale. Since the domain sizes are much smaller than the wavelength of light, they do not scatter. The result is an optically transparent sample in which each domain may produce a different optical function. 

The concept of a multiphase nanostructured composite can be used to prepare a wide variety of optical materials. We have been able to dope two (or more) different optically responsive materials, each of which can be in different phases of the matrix ( e silica phase, the PMMA phase and the interfacial phase), to make multifimctional bulk materials for photonics. For example, we have doped in addition to the fiillerene, which is adsorbed in the interfacial phase, a fluorescent and optically nonlinear chromophore bisbenzothiazole 3,4-didecyloxy thiophene (BBTODT) in the PMMA phase. This nonlinear chromophore was developed by B. Reinhardt and co-workers at the Polymer Branch of U.S. Air Force Wright Laboratory 14). 

Gvishi, R., Bhalwaker, J., Kumar, D.N., Ruland, G., Narang, U., and Prasad, P.N. (1995) Multiphasic nanostructured composites for photonics fullerene-doped monolith glass. Chem. Mater.,... 

Scanning electron microscopy (SEM) is one of the very useful microscopic methods for the morphological and structural analysis of materials. Larena et al. classified nanopolymers into three groups (1) self-assembled nanostructures (lamellar, lamellar-within-spherical, lamellar-within-cylinder, lamellar-within-lamellar, cylinder within-lamellar, spherical-within-lamellar, and colloidal particles with block copolymers), (2) non-self-assembled nanostructures (dendrimers, hyperbranched polymers, polymer brushes, nanofibers, nanotubes, nanoparticles, nanospheres, nanocapsules, porous materials, and nano-objects), and (3) number of nanoscale dimensions [uD 1 nD (thin films), 2 nD (nanofibers, nanotubes, nanostructures on polymeric surfaces), and 3 nD (nanospheres, nanocapsules, dendrimers, hyperbranched polymers, self-assembled structures, porous materials, nano-objects)] [153]. Most of the polymer blends are immiscible, thermodynamically incompatible, and exhibit multiphase structures depending on the composition and viscosity ratio. They have two types of phase morphology sea-island structure (one phase are dispersed in the matrix in the form of isolated droplets, rods, or platelets) and co-continuous structure (usually formed in dual blends). 

Different assembly strategies for preparation of magnetic polymer composites were established by multiphase polymer studies during their evolution from micro-to nanostructures. 

Q contains the non-topological structure parameters of the material s nanostructure. This means that Q depends only on the composition and contrast of the phases and not on their arrangement and shape. For multiphase systems this fact can be deduced by application of the Fourier-slice theorem and the considerations which lead to POROD s law [46]. In particular, by applying Fourier-slice theorem one obtains... 

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