Ether Monomers

Both alkyl and aryl vinyl ethers and a variety of unsaturated cyclic ethers will undergo free-radical copolymerization with MA, under mild conditions, to give equimolar copolymers. DuPlessis and coworkers have shown that dialkyl maleates and alkyl vinyl ethers will also undergo equimolar copolymerization. This occurs even though all of the monomers are very sluggish to free-radical homopolymerization. In some cases, spontaneous or thermal copolymerization can even occur between vinyl ethers and MA, such as 1,2-dimethoxyethylene, p-dioxene, and conjugated dihydro-anisole. It is also known that vinyl ethers will polymerize in the presence of amide-MA mixtures, with the amide-MA CTC playing the role of initiator.  

Spontaneous copolymerization of vinyl ethers with MA are accelerated in the presence of trialkylaluminum compounds.For example, spontaneous copolymerization of -butyl vinyl ether-MA readily occurs in the presence of trioctylaluminum. Electron spin resonance, infrared, cryoscopic, and other analytical studies show that activation is achieved by the trioctylaluminum- 

A commercially useful product, the equimolar methyl vinyl ether MA copolymer is easily prepared in the aromatic solvents at In the 

High-molecular-weight copolymer is produced by a large excess of methyl vinyl ether, methylene chloride solvent, lauroyl peroxide initiator, and conducting the copolymerization under pressure at 40-60°C. The copolymers are easily isolated and the excess ether is recovered for recycling. 

A variety of other alkyl vinyl ethers, such as ethyl, 

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Vinyl ether monomers and polymers, AJ-Vinylamide polymers. 

One class of materials with some inherent PSA properties includes polyvinyl-ethers. Vinyl ether monomers are industrially derived from the reaction of acetylene with alcohols [117]. The most common alcohols used are methanol, ethanol or isobutanol. A generic structure of the vinyl ether is shown below ... 

Anon, Rockwell Inti Corp, Energetic Epoxy-Ether Monomers And Their Polymers , FrP 2196998 (1974) CA 83, 60349 (1975)... 

Vinyl ethers constitute a third class of monomers which have been cationically polymerized in C02. While fluorinated vinyl ether monomers such as those described in Sect. 2.1.2 can be polymerized homogeneously in C02 because of the high solubility of the resulting amorphous fluoropolymers, the polymerization of hydrocarbon vinyl ethers in C02 results in the formation of C02-insoluble polymers which precipitate from the reaction medium. The work in this area reported to date in the literature includes precipitation polymerizations and does not yet include the use of stabilizing moieties such as those described in the earlier sections on dispersion and emulsion polymerizations (Sect. 3). 

The objective of the present work was to determine the influence of the light intensity on the polymerization kinetics and on the temperature profile of acrylate and vinyl ether monomers exposed to UV radiation as thin films, as well as the effect of the sample initial temperature on the polymerization rate and final degree of cure. For this purpose, a new method has been developed, based on real-time infrared (RTIR) spectroscopy 14, which permits to monitor in-situ the temperature of thin films undergoing high-speed photopolymerization, without introducing any additive in the UV-curable formulation 15. This technique proved particularly well suited to addressing the issue of thermal runaway which was recently considered to occur in laser-induced polymerization of divinyl ethers 13>16. 

Alkenyloxystyrene monomers such as 4-allyloxystyrene are useful components of photocured cationically polymerizable compositions. Used alone or in combination with divinyl ethers they provide low viscosity formulations, which are excellent solvents for commercial onium salt photoinitiators. Photocuring rates are comparable to vinyl ether monomers and the initially photocured alkenyloxystyrene polymers may be further heat processed to yield crosslinked phenolic type resins having outstanding thermal resistance properties. The new materials have good adhesive properties and are potentially useful where a combination of ease of processability and high performance is required. 

This chemistry was also performed on one trisphenol, 1,1,1 -tris(4-hydro-xyphenyl)ethane (THPE). The resulting tris(trifluorovinyl ether) monomer forms a thermoset polymer upon curing. 

Figure 3.3. Synthesis of trifluorovinyl ether monomers and perfluorocyclobutane aromatic ether polymers.

Hydroxy-containing fluorovinyl ether monomers (5,6) were prepared in excellent yields (80-90%) in a single step from the corresponding esters (1,3)12"14 with sodium borohydride in absolute ethanol. Protection of the sensitive vinyl ether groups was not required during the reduction. In contrast, the use of a more powerful reducing agent, such as lithium aluminum hydride, resulted in the reduction of the double bond ... 

The hydroxylated vinyl ether monomers can be further fuctionalized on the hydroxy group. For example, the conversion of 5 to its various derivatives 16-20 is straightforwad, and thus provides the entry to new difunctional fluorinated monomers.23... 

Carbon dioxide has also proven to be an exemplary medium for the polymerization of TFE with perfluorinated alkylvinyl ether monomers containing sulfonyl fluoride such as CF2=CF0CF2CF(CF3)0CF2CF2S02F (PSEVPE). As seen in Table 13.2, the dramatic difference in the number of acid end groups between the commercial sample and those made in C02 indicates that chain-transfer processes stemming from vinyl ether radical arrangement are not nearly as prevalent in C02 as in conventional systems. 

Table 13.2. Copolymerization of (S02F)-Functional Perfluorinated Alkyl Vinyl Ether Monomer with TFE...

After isolation, the intermediate products were reacted with zinc in acetonitrile or a glyme solvent to provide the trifluorovinyl ether monomers. This reaction with zinc is also sensitive to the presence of protic substances in the reaction mixture, and forms the same tetrafluoroethyl ether by-product in an undesirable side reaction. The reaction of the 2-bromotetrafluoroethyl ether reactants with zinc involves the formation of zinc organometallic species as an intermediate, and this species is sensitive to hydrolysis by water or acidic substances (Figure 3.6). 

Thia-8-oxoguanosine, 2 823 Thiaboranes, 4 170, 204 preparation, 4 205 Thiacrown ether monomers, 23 707 Thiacrown ether polymer ligands, 23 702 Thiamine, 2 737-738, 25 781, 795-796. 

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