Vinyl-type monomers

DiaUyl fumarate polymerizes much more rapidly than diaUyl maleate. Because of its moderate reactivity, DAM is favored as a cross-linking and branching agent with some vinyl-type monomers (1). Cyclization from homopolymerizations in different concentrations in benzene has been investigated (91). DiaUyl itaconate and several other polyfunctional aUyl—vinyl monomers are available. 

A number of reports in the literature describe the use of alkyl thiosulfates to modify reactive vinyl type monomers and/or preformed polymers with the expressed goals of producing polymers with enhanced water solubility (1-61. The alkylthiosulfate modified polymers have been shown to be thermally and photochemically reactive and capable of producing crosslinked films with varying degrees of stability (5). 

Most examples of polymerization used to create nanoparticles occur by a free radical mechanism involving distinct initiation, propagation, and termination processes [39]. Polymerization occurs within a continuous liquid medium, which also comprises the monomer, initiator, and a surfactant. Four different polymerization techniques are described to polymerize vinyl type monomers, namely ... 

The initiation of polymerization by ultraviolet radiation has been of particular interest in the study of free radical processes [1,2]. The test tube demonstration described here is simple and may be used to evaluate the polymerizabil-ity of new monomers or to study some of the physical properties of a polymer. Although the method is particularly effective for acrylic and methacrylic monomers, it may also be applied to the polymerization of a wide range of vinyl -type monomers. 

Interestingly, such a fluoroolefin is quite reactive in contrast to long per-fluorinated chain-vinyl type monomers (e.g. CnF2n+1CH = CH2 with n > 1). 

During the early 1960 s a new class of chemicals containing one or more double bonds was used to treat wood vinyl type monomers that could be polymerized into the solid polymer by means of free radicals (2). This vinyl polymerization was an improvement over the condensation polymerization reaction because the free radical catalyst was neither acidic nor basic, nor does the reaction leave behind a reaction product that must be removed from the final composite, such as water. The acid and base catalysts used with the other treatments degrade the cellulose chain and cause brittleness of the composite. Vinyl polymers have a large range of properties from soft rubber to hard brittle solids depending upon the groups attached to the carbon-carbon backbone. 

Some of the most important linear or chain polymers belong to the category of homopolymers, for example, polyethylene, polyvinylchloride, and polypropylene (see Table 2.1) where the vinyl-type monomer (see Figure 2.34) with different side groups, R, is repeated [8,195],... 

In order to find out how the specific base-base interactions occurring between complementary nucleic acid bases can be utilized for free-radical polymerization systems, the radical copolymerization of vinyl-type monomers bearing complementary nudeic add bases, MAOA (24 a) and MAOU (26 a) was studied in different solvents, using AIBN as the initiator34. ... 

A binding site consists of a polymerisable group, generally a vinyl-type monomer, with a second functional group attached, capable of interacting with the template molecule. After polymerisation the vinylic residue is part of the... 

There are, in general, two ways to prepare new polymers which have valuable and "useful properties. One of them involves the synthesis of a new monomer, which embodies by virtue of its chemical nature some interesting and attractive features. If one then polymerizes such a monomer, one finds in the polymer the desired properties resulting from repetition of a large number of monomeric units. In this manner, many new addition polymers have been made from vinyl-type monomers, which had reactive groups such as —CH—CH2, —SH, or —NHCH2OH. The... 

Copolymerization of Ethylene with Vinyl-Type Monomers... 

Considerable efforts have been directed, during the last few years, to grafting various vinyl and acrylic monomers on cellulosic fibers or films in order to modify their properties in a predetermined way. It was shown that one can graft large amounts of vinyl-type monomers, such as acrylonitrile or acrylic esters on rayon, cotton, cellophane, paper, and wood, thus modifying the properties of the base material in many respects, and improving, particularly, dimensional stability, water repellency, and resistance to thermal and chemical degradation. 

Treatment of solid wood over the years for increased utility included many chemical systems that affected the cell wall and filled the void spaces in the wood. Some of these treatments found commercial applications, while some remain laboratory curiosities. A brief description of the earlier treatments is given for heat-stabilized wood, phenol-formaldehyde-treated veneers, bulking of the cell wall with polyethylene glycol, ozone gas-phase treatment, ammonia liquid- and gas-phase treatment, and p- and y-radiation. Many of these treatments led to commercial products, such as Staybwood, Staypak, Im-preg, and Compreg. This chapter is concerned primarily with wood-polymer composites using vinyl monomers. Generally, wood-polymers imply bulk polymerization of a vinyl-type monomer in the void spaces of solid wood. 

Most vinyl type monomers form during polymerization Fl-T type polymers. However, a certain proportion of H-H polymer may be formed during radicalic polymerization. An example of differentiation between H-T and H-H polymer using pyrolysis data was reported for polystyrene [3]. Although during pyrolysis the yield of monomer is not different between H-T and H-H polymers, other small molecules may indicate the structural differences, as shown in the schemes below that indicate the main compounds formed in the thermal decomposition process for the H-T polymer ... 

Except in monomers like ethylene and tetrafluoroethylene that have identical substituents, the two ends of the double bond in a vinyl type monomer are distinguishable. One C of the double bond can be arbitrarily labeled the head and the other the tail of the monomer, as shown below for vinyl chloride (IV)... 

Except in monomers like ethylene and tetrafluoroethylene where the substituents on the two carbons are identical, the two carbons of the double bond in a vinyl type monomer are distinguishable. One of them can be arbitrarily labeled the head and the other the tail of the monomer, as shown below for vinyl chloride (IV). During polymerization, the monomer in principle can be joined by head-to-tail or head-to-head/tail-to-tail (V) additions, as shown by Eqs. (P2.7.1) and (P2.7.2), respectively. However, head-to-tail enchainmenf is the predominant constitution of most vinyl monomers (see Problem 2.7). 

The simplest way to cany out an addition polymerization reaction of a vinyl-type monomer, CH2=CHX, is to let it stand at room terpperature over prolonged periods of time. However, not only is this pr dure economically unfavorable if attempted on an industrial scale, but the reaction itself is exothermic and may get out of hand if spontaneous polymerization starts in large masses. Technical polymerizations are, therefore, always carried out uuj er controlled heat and catalyst conditions which are closely followed throughout the course of the reaction. 

In connection with bulk polymerization experiments of diallyl o-phthalate, it should be pointed out that this monomer behaves quite differently from vinyl-type monomers in that its rate of polymerization increases linearly with initiator concentration. This phenomenon is conveniently studied by use of a gel-time meter [100]. This instrument also is used to demonstrate that hydroquinone is a more effective inhibitor of the polymerization of a 1% solution of dibenzoyl peroxide in diallyl o-phthalate at 100°C than r-butyl catechol [100]. 

Radical polymerization of MCMs involves the same elementary steps as with ordinary vinyl-type monomers, and the stationary rate (Wp) of the reaction is described by the classical kinetic equation of radical polymerization, the order with respect to the initiator being 0.5 and with respect to the MCM close to 1.0. 

Metal complexes bound to a polymer support most frequently induce ionic polymerization of olefins, dienes and acetylenes, and less commonly radical polymerization of vinyl-type monomers, acting at all reaction stages initiation, chain propagation and termination. Active sites for the addition of monomer molecules to the growing polymer chain can in many cases be regenerated yielding new polymer chains (catalysis via a polymer chain). 

Complexes of Cu(II), Fe(III), V(V), etc., immobilized on polymers, are often used as components of redox systems which are effective as initiators of vinyl-type monomer polymerization. For instance, the system vanadylpolycarboxylate-thio-... 

Uses As comonomer with vinyl-type monomers to produce crosslinked polymers reactive diluent in radiation-cured coatings Manuf./Distrib. ABCR UK http //www.abcr.de, Aldrich http //www.sigma-aldrich.com, Alfa Aesar http //www.aifa.com, Monomer-Polymer Dajac Labs Narchem http //www. narchem. com Allyl alcohol... 

Polyester Resin—Thermosetting resins produced by dissolving unsaturated, generally linear, alkyd resins in a vinyl type monomer such as styrene and capable of being crosslinked by vinyl polymerisation using initiators and promoters. 

The vast majority of chain reaction poly-merize-tions are those generally known as addition polymerizations involving the conversion of vinyl-type monomers. 

Triallyl cyanurate (TAC, 2,4,6 triallyloxyl-1,3/5-triazine) n. (CH2=CHCH20C)3N3. This heterocyclic compound, a solid below 110°C, is highly reactive and is used in co-polymerizations with vinyl-type monomers to form allyl resins. It is also used to... 

Unsaturated polyester resins are complex polymers resulting from a crosslinking reaction of a liquid unsaturated polyester with vinyl-type monomers, most often a styrene monomer. The unsaturated polyester is formed via the condensation reaction of an unsaturated dibasic acid or anhydride, a saturated dibasic acid or anhydride, and a polyfunctional alcohol [32]. 

A typical composition for BMC and SMC includes base resins, catalysts, peroxides accelerators, fillers/chopped GF, thickeners and other additives. The base resins that are usually used are either polyester-based (orthophthalic or isophthalic), which are used with styrene, acrylic, vinyl toluene or di-allyl-phthalate (DAP) monomers, as crosslinkers, or styrene type monomers for general purpose products. Acrylic base resins are used for low shrinkage, while vinyl type monomers for high hot strengths (heat deflection temperatures). Catalysts are used for polyester type resins. Peroxides, such as benzoyl peroxide (BPO) and butyl perbenzoate are used as high temperature catalysts. 

---