Monomer ether-linked

Ether-linked bisphthalonitriles were synthesized by Mr. T. R. Price of the Naval Research Lab. A number of monomers containing various aliphatic and aromatic "linking groups" between the phthalonitrile functions are available three representative aromatic monomers were selected for this study... 

Another series of monomers that was prepared began with the displacement of an unactivated aryl halide with phenate anion in the presence of a copper catalyst [113-115], Figure 46 outlines the basic route followed for the preparation of 114a. The sequence of reactions started with 4-bromobenzocyclobu-tene, 2 which was reacted with the phenate of p-acetamidophenol, 112a in the presence of copper (I) chloride as a catalyst, to afford the ether linked product 113a in a yield of 50-75%. 

Polyether-b-polyester dendrimer 3,5-dihydroxybenzyl alcohol as monomer for ether-linked fragments and 2,2,2-trichloroethyl 3,5-dihydroxybenzoate for ester linked fragments radially alternating the dendritic segments produced segmented-block polymer and concentric alternation gave layer-block polymer spectroscopy, thermal characterization described. [269]... 

Peroxy-linked dimers are also formed from linoleate hydroperoxides in the presence of free radical initiators and copper palmitate, and carbon-carbon linked dimers in the presence of copper catalysts. Decomposition of methyl linoleate hydroperoxides at 210°C under nitrogen produces mainly carbon-carbon linked dimers (82%), monomers with loss of diene conjugation, volatile compounds (4-5%) and water. The resulting dimers contain carbonyl and hydroxyl groups and double bonds scattered between carbon 8 and carbon 10. Linoleate hydroperoxides can dimerize by one of the termination reactions discussed in Chapter 1. The termination reactions involving combination of alkyl, alkoxyl, or peroxyl radical intermediates produce dimers with carbon-carbon, carbon ether, or peroxy links. The carbon-carbon and carbon-oxygen linked dimers are favored at elevated temperatures and the peroxy-linked dimers at ambient temperatures. The peroxy-linked dimers may also decompose to the ether-linked and carbon-carbon linked dimers via the corresponding alkyl and alkoxyl radical intermediates. 

FIGURE 11.2 Straight-chain starch molecule, amylose (CAS 9005-82-7). It is made up of glucose units polymerized by dehydration to form ether links. Once incoipoated into the chains, they are called anhydroglucose units. The a-links shown create a polymer that has a chemically similar monomer but is physically and chemically different from cellulose, formed using p-links (see Figure 10.1),... 

These three monomers are linked together by enzymatic dehydrogenation via phenoxy radicals into a three-dimensional irregular polymer network with C-C and C-O-C linkages. One third of the phenyl-propane units are linked by carbon-carbon bonds, two thirds by ether bonds. Lignins of different origin differ in their structure. 

A munber of other synthetic polymer networks have been developed and commercialised for liquid chromatography including polyvinylacetate cross-linked with butanediol divinyl ether, Merkogel GPC packings (Merck), polyvinylalcohol, Frac-togel and Toyopearl (Toyo Soda), a hydroxylated acrylic monomer cross-linked with a bifunctional agent, Trisacryl (Sepracor) and a hydrophilic vinyl polymer, TSKgel PW (Toyo Soda). 

Hexamethylolmelamine can further condense in the presence of an acid catalyst ether linkages can also form (see Urea Eormaldehyde ). A wide variety of resins can be obtained by careful selection of pH, reaction temperature, reactant ratio, amino monomer, and extent of condensation. Eiquid coating resins are prepared by reacting methanol or butanol with the initial methylolated products. These can be used to produce hard, solvent-resistant coatings by heating with a variety of hydroxy, carboxyl, and amide functional polymers to produce a cross-linked film. 

The polymeric products can be made to vary widely in physical properties through controlled variation in the ratios of monomers employed in thek preparation, cross-linking, and control of molecular weight. They share common quaHties of high resistance to chemical and environmental attack, excellent clarity, and attractive strength properties (see Acrylic ester polymers). In addition to acryHc acid itself, methyl, ethyl, butyl, isobutyl, and 2-ethylhexyl acrylates are manufactured on a large scale and are available in better than 98—99% purity (4). They usually contain 10—200 ppm of hydroquinone monomethyl ether as polymerization inhibitor. 

Synthesis of Silicone Monomers and Intermediates. Another important reaction for the formation of Si—C bonds, in addition to the direct process and the Grignard reaction, is hydrosdylation (eq. 3), which is used for the formation of monomers for producing a wide range of organomodified sihcones and for cross-linking sihcone polymers (8,52—58). Formation of ether and ester bonds at sihcon is important for the manufacture of curable sihcone materials. Alcoholysis of the Si—Cl bond (eq. 4) is a method for forming silyl ethers. HCl removal is typically accomphshed by the addition of tertiary amines or by using NaOR in place of R OH to form NaCl. 

---