Polyvinylene

Solution-processible polymers with large band gaps and relatively high triplet energies may also be suitable for use as host materials. Examples of these include polyalkylfluorene (POF, 126), polyvinylene cabazole (PVK, 127), and rigid polycarbazoles (e.g., PCOX, 128) (Scheme 3.39). They can be used as host materials for a wide range of colors. Details will be described in Chapter 4. 

Dehydrochlorination of poly vinylidene chloride and chlorinated polyvinyl chloride was carried out. High chlorine content in the polymers (more than 60%) provides the formation of chlorinated conjugated polymers, polychlorovinylenes. The reactivity of chlorinated polyvinylenes contributes to the sp carbon material formation during heat treatment. Synthesis of porous carbon has been carried out in three stages low-temperature dehydrohalogenation of the polymer precursor by strong bases, carbonization in the inert atmosphere at 400-600°C and activation up to 950°C. 

Remarkably some polymers are ferroelectric. Polyvinylene fluoride, as a thin film (approximately 25 /mi thick) is used in Shockwave experiments to measure stress. The pressure range over which this polymer operates is an order of magnitude larger than that of quartz or lithium niobate. 

In the P phase of polyvinylene fluoride (PVDF), the CF2 groups in a polymer chain are all pointing in the same direction (Figure 9.20), so that a dipole moment... 

Many other types of polymer have been prepared which exhibit semiconductivity. All obey the equation a = a0exp — E/kT. These include xanthene polymers (109, 110), polymerized phthalocyanines (111, 112), epoxides and polydiketones (86, 113), polypentadienes (114), polydicyanoacetylenes (115), polyvinylferrocene and substituted ferrocene (116, 117, 118, 119), polymeric complexes of tetracyanoethylene and metals (120), poly(vinyl chloride) and poly(vinylidene chloride) (121), polyvinylene and polyphenylene (122) and poly(Schiff s bases) (123, 124). 

Acetylene was first polymerised to polyacetylene (polyvinylene) according to scheme (1) by Ziegler, who patented a process employing new catalysts prepared from transition metal salts and metal alkyls [1] ... 

One of the authors of this review observed heterogeneous ignition and combustion in air of the highly reactive polyvinylene, a polymer with an acyclic system of conjugated —CH = CH— bonds. After only minor heating, this originally black polymer becomes red and finally transforms into a light-yellow nonvolatile oxidized product. 

The publication by Chiang et al. [1] led to a huge surge in interest in synthetic metals. In less than a decade, most of the monomer building blocks that we know today had been identified and many procedures for polymeric synthesis had been established. The chemical structures are illustrated in Figure 1.1. (In the nomenclature used in Figure 1.1, polyacetylene would be called polyvinylene. This is because some - common - names derive from the compound that is polymerized, while others, more correctly according to lUPAC conventions, use the monomeric unit in the product polymer.)... 

The thermal elimination process can be applied to most substituted groups in vinyl polymers by controlled pyrolysis at 600-700°C, producing polyvinylene compounds, for example, by the splitting off of acetic acid from poly(vinyl... 

On the other hand. Balcar et al. showed that the immobilization of [Rh(cod)OCH3]2 on mesoporous MCM-41 provides an inorganie hybrid catalyst, which is effective for polymerization of various substituted phenylacetylenes into substituted polyvinylenes (investigated for their interesting photoelectrical and optical properties) with molecular weight between 50.000 and 180,000 and high cis-transo d strueture. 

In view of the inactivity of metallacarbenes in ADMET self-polymerization of divinylsilicon compounds, we present here a new synthetic route to polyvinylene-silylenes and related polymers. 

Oriented Polyvinylene Film Fig. 17-12. Structure of a dichroic polarizer. 

Homopolymerisation is promoted by tertiary amines and certain Lewis acids, which do not contain acidic hydrogen. The amines promote a mechanism in which an anion is the propagating species the Lewis acids promote a cationic propagation mechanism. In polyepoxide resins, both mechanisms lead to polymers that are essentially highly crosslinked polyvinylene ethers in which each vinylene unit carries a crosslink. 

Our initial objective was to prepare organic polymeric systems which may be modified to electrically conducting materials. The approach was to obtain the butadiyne polymer in a thin film form by taking advantage of the synthetic procedure, characterization techniques and struc re-property insight that have been developed for polyacetylene. The formation of a partially crosslinked polyvinylene system that may reduce or eliminate the requirement of charge carrier transfer by intermolecular chain contact was envisioned (Eq. 2). 

Elemental, infrared, and NMR analyses of the materials obtained with tertiary amine catalysts suggested the polymeric structure consisted essentially of c/5-polyvinylene-ketoanhydride units. Ring opening, followed by decarboxylation, was used to explain the proposed structure 12 [Eqs. (28) and... 

The simplest systems to start with are the high m.wt. homopolymers of the fluoroethylenes for which complications due to branching, end groups, etc., are minimal. In this section, we therefore outline the results from studies on polyethylene (high density), polyvinyl fluoride, polyvinylidene fluoride, polyvinylene fluoride, polytrifluoroethylene and polytetrafluoroethylene. 

The Cis spectrum of polyvinyl fluoride shows two partially resolved peaks of equal area corresponding to HF and 1CH2 carbons whilst for polyvinylene fluoride in addition to the main peak corresponding to HF carbons and hydrocarbon calibration peak, there... 

Absolute binding energies calculated for model systems of polyethylene, polyvinylene fluoride and PTFE. 

Fig. 5 shows experimental charge distributions determined for polyvinylene fluoride and polytrifluoroethylene. These show rather effectively the large net migration of electron densities from carbon and hydrogen to fluorine. 

Fig. 5. Experimental charge distributions for polyvinylene fluoride and polytrifluoroethylene.

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