Epitaxial polymerization crystalline

Two diacetylenes have been epitaxially polymerized as thin films in contact with alkali halide substrates. These films in contact with alkali halide substrates. These films consisted of highly oriented single crystals aligned along both <110> directions of the substrate. The structures of both poly(TCDU) and poly(DMDA) were modified by this technique and, in all cases, highly crystalline near-perfect films were achieved. 

The first Involves a technique we have termed epitaxial polymerization. Monomers are crystallized on crystalline substrates. Lattice matching allows the variation of monomer structure and morphology, yielding different polymer structures and morphologies... 

The orthogonal projection of the epitaxial poly(DMDA) could not be indexed using the unit cell data for the bulk polymerized crystal (8). However, poly(DMDA) cannot usually be polymerized to completion or to high crystallinity in the bulk due to cross-linking. The use of an epitaxial substrate may have controlled the polymerization process that led to oriented single crystals. 

When classifying chemical products, Seider et al. [3] identify three categories (1) basic chemicals (commodity and specialty chemicals, bio-materials, and polymeric materials) (2) industrial chemicals (films, fibers, paper,. ..) and (3) configured consumer products (dialysis devices, post-it notes, transparencies, drug delivery patches,. ..). In the manufacture of epitaxial silicon wafers, a thin film of crystalline silicon is often deposited on a polished crystalline silicon... 

Orbital energies of polysilanes are very sensitive to molecular conformation. Structured PDMS layers have been deposited by epitaxy on various substrates inducing various conformations via self-arrangement of the polymeric chains, either normal or parallel to the surface of the substrate, such as PTFE layers or freshly cleaved crystalline surfaces of KBr, NaCl, or KC1.5 Highly crystalline PDMS layers have been deposited on substrates and the UV absorption spectra are found to depend on the orientation of the crystal with respect to the substrate, as shown in Figure 6. 

LiNb(OEt)6 (144) features a polymeric helix.298 Alternating Nb(OEt)6 octahedra are cw-linked to four-coordinate Li ions. It produced epitaxial LiNb03 films upon spray chemical vapor deposition.299 300 The presence of H atoms [3 to O allowed production of water via the classic autocatalytic decomposition pathway. This in turn led to production of oxide via hydrolysis.301 In contrast, although the binuclear analog [LiNb(OCH2SiMe3)6]2 (145) pyrolyzed to crystalline LiNb03, it did not deposit films upon spray deposition, apparently due to the lack of (3 H atoms.301... 

All monomer epitaxial crystallization and polymerization is controlled by the substrate surface and results in new, highly oriented crystalline films with new structures and properties which are presently under investigation. 

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