Post-deposition polymerization

Polydiacetylenes are particularly interesting for their optical and electrical properties. For example, large third-order nonlinear optical effects can be produced. Extensive electronic conjugation is required for such behaviour and polydiacetylenes produce the largest values yet observed for example, the solid state polymer of (20) exhibits a value of esu, and the LB polymer of (10) with n = 16,m = S exhibits a non-resonant value of 4 x 10 esu. Insulating properties are 

A similar family of polyimides has been described by other workers [38]. The polyamic acid alkylamine salt (23) was used to form a surface monolayer, and this was then deposited into multilayers by the LB technique. By treating the deposited films with acetic acid, a highly stable polyimide multilayer (24) was produced. The major difference between these polyimides and those of structure (22) is the mode of preparation. In this case a chemical method is used, whereas thermal cyclization was used for (22). LB polyimide films of structure (24) have been found to be very stable in various organic solvents and exhibit insulating behaviour (electrical and thermal) comparable to conventional polyimide films. 

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The polymerization of LB materials during deposition (as monolayers either on the subphase surface or on a substrate) is usually experimentally more difficult and time-consuming than either pre- or post-deposition polymerization. There are thus fewer examples in the literature of this mode of polymerization. 

Hie use of a forced-flow polymeric membrane reactor has also been described for room temperature polychlorinated biphenyl (PCB) dechlorination. Core/shell Fe/Pd nanoparticles were synthesized on the pore walls of PVDF microfiltration membranes functionalized with poly(acrylic acid) (PAA). PAA functionalization was achieved by in situ free radical polymerization of acrylic add in the microfiltration membrane pores. Ferrous ions were then introduced into the membranes by the ion-exchange process. Subsequent reduction resulted in the in situ formation of 20-40 nm Fe nanoparticles. Bimetallic nanoparticles could be formed by post-deposition of Pd. 

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... 

T. Wydeven developed a plasma process that significantly improves the hardness of optical lenses and, consequently, leads to greater scratch resistance (7. Vinyl-trimethoxysilane films were deposited on transparent polycarbonate lenses by plasma polymerization. The adherent, clear films protect the substrate from abrasion and also serve as antireflection coatings. Post-treatment of the vinyltrimethoxysilane films in an oxygen glow discharge fui ther improved the abrasion resistance. 

It is the aim of this chapter to give an overview on both chemical and electrochemical techniques for producing metallic-particle-based CP nanocomposite materials and to outline the progress made in this field. The various synthetic approaches are organized in such a way as to present first those involving metal particle deposition in the course of polymerization, and subsequently post-polymerisation procedures that involve chemical, electrochemical, or adsorption processes (Figure 7.1). Well-established approaches, along with some newly developed techniques will be discussed, with special emphasis on those that are still underdeveloped. Synthesis of metal oxide particle-based CP composites (see e.g. [8]), as well as modification of CPs with transition-metal complexes (see e.g. [5]) remain outside the scope of this chapter. 

Since in multilayer interference systems, denser layers can be deposited, improved abrasion resistance is expected compared to porous coatings. Multilayer AR films can readily be deposited from traditional polymeric sols, and low temperature post-treatments allow processing such films on polymer substrates. For instance, multicomponent AR coatings have been applied on PC and acrylate substrates by hydrolysis and condensation of silanes and various metal alkoxides (Ashley, 1986). However, it seems that low temperature... 

Excellent transport characteristics, solubilization power, and sensitivity to process variables all contribute to the success of the methodology. The generic scheme involves homogenization, impregnation, deposition, and optional post treatment steps such as curing reactions. The mechanism of transport in the porous matrix is permeation and diffusion while the primary mechanisms for deposition are pressure reduction, temperature swing, sorption, and reaction (i.e., polymerization). 

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