Oligomerization of acrylates

Feldman et a .210 211 and Wulff et ul v have examined other forms of template controlled oligomerization of acrylic monomers. The template (23) has initiator and transfer agent groups attached to a rigid template of precisely defined structure.210 "11 Polymerization of MMA in the presence of 23 gave a 3 unit oligo(MMA) as ca 66% of the polymeric product. The stereochemistry of the oligomer was reported to be different" from that of atactic PMMA. 

The products formed by the co-oligomerization of acrylic esters with butadiene (102,106) provide useful information concerning the nature and configuration of the intermediates involved. Naked-nickel, methyl acrylate, and butadiene do not react together.7 However, reaction does occur if the nickel-ligand system is used. The formation of the Diels-Alder adduct between the diene and olefin (a cyclohexene derivative) can be suppressed by adding the reactants dropwise to the catalyst (Table XVI footnote C). 

When it comes to preparing oligomers, i.e., polymers of very low molecular weight, free-radical processes are usually not very useful. In triethyl phosphite, methyl methacrylate has been oligomerized using AIBN as initiator. The resultant product was said to have degrees of polymerization of between 1 and 3 when the ratio of triethyl phosphite to monomer exceeded 1. The oligomerization of acrylic or methacrylic acids in this solvent proceeded without the use of an initiator and were considered to be anionic polymerizations [60]. 

Telomers with degree of polymerization of 10—50 were obtained by redox oligomerization of acrylic acid ... 

The nonsaturated esters with tt-C=C bonds and without activated a-C—H bonds (esters of acrylic acid (CH2=CHCOOR) and esters of vinyl alcohols (RC(0)0CH=CH2)) are oxidized by the chain mechanism with chain propagation via the addition of peroxyl radicals to the double bond. Oligomeric peroxides are formed as primary products of this chain reaction. The kinetic scheme includes the following steps in the presence of initiator I and at p02 sufficient to support [02] > 10 4 mol L-1 in the liquid phase [49]. 

Specific catalytic activity of the composites obtained was at least several times higher than the same value for the random copolymer Nafion (even in an esterification reaction considered to be a diffusion-uncontrolled reaction). For the oligomerization reaction of decene-1 with strong diffusion control, the specific catalytic activity of the composites was 35 times higher than that for the random copolymer. Esterification of acrylic acid and alkylation of mesitilene by a substituted phenol were also performed using the composite catalyst. 

From dimeric to oligomeric sodium acrylate having a molecular weight of 500 was easily biodegraded. However, it seems that the specific microbes utilizing this polyvinyl-type copolymers as a sole carbon source are relatively scarce in the environment, and the biodegradability of these types of copolymers differ according to... 

Influence of temperature on the process of polymerization of acrylic acid in dioxane and toluene was examined. It was found that in dioxane an increase in temperature destroys the oligomeric auto-associations of acrylic acid and gives rise to monomer-solvent association, making matrix effect less pronounced. In toluene, an increase in temperature converts the cyclodimeric autoassociations of the monomer into linear oligomers and the matrix effect appears. 

Template copolymerization seems to be applied to the synthesis of copolymers with unconventional sequences of units. As it was shown, by copolymerization of styrene with oligomers prepared from p-cresyl-formaldehyde resin esterified by methacrylic or acrylic acid - short ladder-type blocks can be introduced to the macromolecule. After hydrolysis, copolymer with blocks of acrylic or methacrylic acid groups can be obtained. Number of groups in the block corresponds to the number of units in oligomeric multimonomer. Such copolymers cannot be obtained by the conventional copolymerization. 

We have recently (2,2) reported the stereoregular anionic oligomerization of 2-vinyTpyridine and various alkyl acrylates in THF and similar low dielectric constant media (Eq. 1) ... 

The coupling of the unsubstituted carbon atom of the mono-olefin with the Cs chain, which was observed in the co-oligomerization of styrene with butadiene, and of acrylic esters with butadiene, is not, however, a general phenomenon. For example, the co-oligomerization of 1-decene with butadiene using nickel-tricyclohexylphosphine as catalyst leads (after... 

A method for producing oligomeric butyl acrylate having a controlled molecular weight containing diethanolamine termini by photopolymerization in microemulsions is described. The sensitizer consisted of methylene blue while the photoinitiator consisted of the diethanolamine free radical. 

One of the most significant steps in the preparation of carbon fibers from acrylic precursor fibers is the oligomerization of the nitrile groups. This reaction has originally been studied in context with the problem of thermal discoloration of PAN (e.g. McCarthney Grassie and McNeill Grassie and Hay It was supposed to lead to a so-called ladder structure ... 

There are reports in the literature showing that ionic initiation of the CN oligomerization may be advantageous under certain conditions (e.g. Grassie Menikheim However, the above discussions indicates that stabilization of acrylic fibers in the absence of added ionic substances is quite feasible, provided proper attention is given to concentration as well as molar volume of the comonomer from an economic point of view it is certainly more attractive. 

Crosslinking by chemical bond formation was tried with maleic anhydride. It is known that the addition of dienophiles such as maleic anhydride or acrylamide reduces color formation ( discoloration ) in acrylic fibers. A reasonable explanation for this phenomenon has been given by Marien It is based on a Diels-Alder reaction of the dienophile with cis-dienic structures created during the oligomerization of the... 

When (2,2 -bipyridine)(cycloocta-l,5-diene)nickel was used as the catalyst various isomeric (2,2 -bipyridyl)nickelaspirocycloalkanes 4 and 5a-c were isolated.As expected, treatment of the dispiro complex 4 with methyl acrylate or maleic anhydride released dispiro[2.1.2.1]oc-tane (1) whereas the complexes 5 with one cyclopropane ring opened gave mainly 5-methyl-enespiroheptane 2. The formation of the 4-methylene isomer (from 5c) has not been observed in the dimerization reaction with other nickel(O) complexes. A few more nickel(O) complexes with an ability to catalyze the oligomerization of methylenecyclopropane have been de-scribed. ... 

Catalysts of this type have been studied extensively for the polymerization of butadiene [32], the oligomerization of styrene [33], and the dimerization of acrylates [34]. Indeed it was my becoming aware of this work that led to all of our subsequent discoveries. 

Scheme 8-4 Kammerer s strategy for template control of acrylate oligomerization.

Exploration of the template controlled free-radical oligomerization of other activated olefins began with standard monomers utilized in bulk polymer synthesis and the template 63. Vinyl acetate and acrylonitrile led only to uncontrolled polymerization, while vinylene carbonate did not react under the standard experimental conditions. More exotic monomers, such as vinyl trifluoroacetate and rert-butyl acrylate, were also unsuccessful. Only methyl acrylate polymerization was arrested by template 64 to provide the macrocyclized product 96 in modest yield as a mixture of five diastereomers (Scheme 8-25). Subsequent studies with the more effective thiophenyl-bearing template 63 at lower temperatures improved this yield to 35%. The diastereomer distribution was reminiscent of the methyl methacrylate-derived product, although no stereochemical assignments were made in this case either. 

A dramatic development in the anionic polymerization of acrylate and methacrylate monomers was the discovery that by addition of lithium chloride it was possible to effect the controlled polymerization of f-butyl acrylate [122]. Thus, using oligomeric (a-methylstyryl)lithium as initiator in THE at -78 °C, the molecular weight distribution of the... 

The Clean Air Act demands the elimination of organic solvents use, hence a number of plasticisers and solvents (such as methylene dichloride (MEK), toluene, xylene) are classified as hazardous, which led to development of new, environment compliant systems to develop, such as water borne systems, or use of rapidly curable/dryable oligomers (i.e., printing inks use oligomeric bis acrylates, polyester acrylates and polyurethane acrylates, which can be crosslinked quickly by UV light with the aid of certain sensitisers). 

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