Condensation polymers epoxides

In the oxidation of polyvinyl chloride, for example, a vital role is played by splitting out of HCl molecules and the formation of double bonds. The oxidation of polyamides proceeds without any appreciable induction period and differs sharply in character from the oxidation of hydrocarbons. The thermooxidative destruction of polysiloxanes also proceeds uniquely. Condensation polymers - epoxide resins, polyary-lates, and polycarbonates begin to be oxidized at comparatively high temperatures, and thus far no methods of stabilizing them are known. 

However, the introduction of stabilizers is essential, since processes of thermal and thermooxidative destruction develop extremely intensively during the use and reprocessing of such polymers, leading to a sharp deterioration of their physicomechanical and dielectric properties. Thus, an extremely urgent problem at the present time is a detailed investigation of the processes of decomposition of condensation polymers for developing a theory of their stabilization. Works in the field of the study of the thermal and thermooxidative destruction of certain condensation polymers (epoxide, phenol-formaldehyde resins, polycarbonate, and polyarylates) are outlined below. 

Phenolic, (I), and naphtholic, (II), condensation polymers containing cyclopentane were previously prepared by Sue et al. (1). These materials were subsequently epoxidized with epichlorohydrin and used in electronic devices as ICs and Lumen solubility indexes (LSIs). In a subsequent investigation by Abe et al. (2) novolak resins functionalized with thiophene, (III), were prepared and used as adhesives. 

As a second example, there is a wide variety of breakdown products and oligomeric products that may be formed from the reactive monomers that are the building blocks of plastics. For plastics, the general assumption has been that any side-reaction products and breakdown products are likely to be significantly less toxic than the monomers, and so restricting the migration of the monomer was accepted as an indirect way to limit any hazard from the oligomers also. Whilst this approach is probably acceptable for addition polymers, such as those made from the unsaturated monomers vinyl chloride, butadiene and acrylonitrile where the unsaturated monomer is far more noxious than their products, the validity of this means of indirect control is questionable for condensation polymers such as polyesters and for polyethers formed from epoxide monomers. 

Another focal point for glycerol utilization has been in the synthesis of condensation polymers by esterification of glycerol with difunctional comonomers such as aliphatic dicarboxylic acids. In the past, monomers such as glycidol (Sunder et al, 1999), which is a highly reactive epoxide, or cis-1,3-0-benzylideneglycerol (Carnahan and Grinstaff,2001) were used as the glycerol-... 

This class of condensation polymers is characteristically recognized by cross-linking from the reactions of epoxide groups. The products are useful as one of the best adhesives for cementing of rigid materials, and as potting compounds for physical protection or encapsulation of electronic devices. 

Condensation polymers such as polyamides and polyesters like PET are a little more difficult but are quite reactive at processing temperatures and can be reacted using groups such as amines and epoxides. 

Terminal modification Epoxide on PPE, phenoxy, PMMA Anhydride on PS, PP, PSF, PAES Carboxylic acid on PS, NBR ester on PPS Hydroxyl on NBR, PS, PSF, PA6 Amine on NBR, PS, PIP, SAN Isocyanate on polyamides, carbodiintide on PPE For both addition and condensation polymers... 

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

In turn the oxazoline-containing polymer may then react very rapidly (e.g. at 240°C) with such groups as carboxyls, amines, phenols, anhydrides or epoxides, which may be present in other polymers. This reaction will link the two polymers by a rearrangement reaction similar to that involved in a rearrangement polymerisation without the evolution of water or any gaseous condensation products (Figure 7.14). 

Oxidation is the first step for producing molecules with a very wide range of functional groups because oxygenated compounds are precursors to many other products. For example, alcohols may be converted to ethers, esters, alkenes, and, via nucleophilic substitution, to halogenated or amine products. Ketones and aldehydes may be used in condensation reactions to form new C-C double bonds, epoxides may be ring opened to form diols and polymers, and, finally, carboxylic acids are routinely converted to esters, amides, acid chlorides and acid anhydrides. Oxidation reactions are some of the largest scale industrial processes in synthetic chemistry, and the production of alcohols, ketones, aldehydes, epoxides and carboxylic acids is performed on a mammoth scale. For example, world production of ethylene oxide is estimated at 58 million tonnes, 2 million tonnes of adipic acid are made, mainly as a precursor in the synthesis of nylons, and 8 million tonnes of terephthalic acid are produced each year, mainly for the production of polyethylene terephthalate) [1]. 

The first report on the coordination polymerisation of epoxide, leading to a stereoregular (isotactic) polymer, concerned the polymerisation of propylene oxide in the presence of a ferric chloride-propylene oxide catalyst the respective patent appeared in 1955 [13]. In this catalyst, which is referred to as the Pruitt Baggett adduct of the general formula Cl(C3H60)vFe(Cl)(0C3H6),CI, two substituents of the alcoholate type formed by the addition of propylene oxide to Fe Cl bonds and one chlorine atom at the iron atom are present [14]. A few years later, various types of catalyst effective for stereoselective polymerisation of propylene oxide were found and developed aluminium isopropoxide-zinc chloride [15], dialkylzinc-water [16], dialkylzinc alcohol [16], trialkylalumi-nium water [17] and trialkylaluminium-water acetylacetone [18] and trialkyla-luminium lanthanide triacetylacetonate H20 [19]. Other important catalysts for the stereoselective polymerisation of propylene oxide, such as bimetallic /1-oxoalkoxides of the [(R0)2A10]2Zn type, were obtained by condensation of zinc acetate with aluminium isopropoxide in a 1 2 molar ratio of reactants [20-22]. 

Catalysts obtained from metal alkyl and a bi- or trifunctional protic compound, e.g. in systems such as AlEt3—H20 [17], ZnEt2—H20 [16] and ZnEt2—Ar(OH)3 [31], which are characterised by the appearance of associated multinuclear species with condensed metal atoms ( Mt—O—Mt—O ), also form epoxide polymers with a very high molecular weight and broad molecular weight distribution therefore, in this case also, only a small fraction of the metal species in the catalyst is effective for the polymerisation. 

Characteristic of these models of active sites is the appearance of the OZn O Zn(0)Et species. Considering the structural properties of the discussed catalysts as well as the polymer chain microstructure and the structure of the end groups of poly(propylene oxide) obtained with the PhOZnOCeHi ( -Bu)OZnEt catalyst, a concerted mechanism of epoxide ring-opening polymerisation with catalysts containing multinuclear species, including those with condensed zinc atoms, has been postulated [65,74] ... 

Epoxyolefins. Epoxyolefins can be obtained in fair yield by addition of aldehydes in DMSO dropwise to the reagent. Polymers are also formed by aldol-type condensation. A mixture of unscparable diastereoisomeric epoxides is formed. The reaction of citronellal (1) to give 8,9-epoxy-2,6-dimethyl-2-nonene (2a, 2b) is formulated. 

Gothelf and coworkers described chiral manganese-salen-bridged polymers obtained by condensation of a trialdehyde with chiral diamines in the presence of Mn(OAc)2 [34]. The polymers were tested as catalysts in the epoxidation of... 

A number of hydroxylated water soluble polymers were examined as coreactants with polymer 52 in the absence of calcium alginate, and were judged on the basis of the rate of gel formation and the physical properties of the gel These polymers included sodium alginate, polyvinyl alcohol, and copolymers of HEMA with MAA. Of the polymers tested, best results were obtained with polymer 10a, a copolymer of HEMA with a mole fraction of about 10% MAA, which rapidly produced an elastic gel on exposure to polymer 52 in solution. Simple condensation of the carboxyls in polymer 10a with the epoxide functionality was ruled out as a competing reaction due to the measurable but slow reaction between polymer 52 and poly methacrylic acid. It is, therefore, likely... 

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