Acrylic anhydride, cyclopolymerization

The radical polymerization of acrylic anhydride(AA) as a typical 1,6-diene has been investigated in detail in terms of cyclopolymerization. Thus, in 1958 Crawshaw and Butler(31) and Jones(32) have independently demonstrated that AA could be polymerized in solution by an alternating intramolecular-intermolecular chain propagation or cyclopolymerization, leading to the formation of saturated, linear polymers consisting exclusively of six-membered ring anhydride structure. Later, Mercier and Smets(33)... 

Cyclopolymerization is an intramolecular ring formation reaction. For example, as well as double bonds attached to the main chain [Equation (16-54a), rings in the main chain (Equations (16-54b) and (16-54c)] can also be formed in the polymerization of the acrylic anhydride, a 1-6 diene ... 

Thus, we investigated in detail the factors influencing intramolecular addition modes in the radical cyclopolymerization of some unconjugated dienes, including diallyl and dimethallyl dicarboxy-lates, acrylic and methacrylic anhydrides, and allyl -substituted acrylates and discussed the selectivity of reaction mode of intramolecular hh or ht addition in terms of the thermodynamical standpoint. The present article gives a summary of our recent work including published papers(18-23). 

On the other hand, we reexamined in detail the ring size of the cyclic structural units of poly-AA s by means of IR, 1H-NMR, and C-NMR spectroscopy these analytical procedures were applied to the structural analysis of poly-AA, the poly(acrylic acid) derived from hydrolysis of the poly-AA, and the poly(methyl acrylate) obtained by subsequent esterification of the poly(acryl-ic acid) in comparison with the corresponding model polymers of five- or six-membered ring structure. Then, we investigated in detail the effects of polymerization conditions on the ring size of poly-AA s, i.e., on the intramolecular addition modes in the cyclopolymerization of AA since five- or six-membered ring anhydride structure can be formed via intramolecular hh or ht addition of the uncyclized radical to the internal double bond(22,23). 

As the example of 2-vinyl butadiene has already shown, the free radical polymerization of dienes is particularly interesting. Because of the two bifunctional double bonds, 1,4-dienes, CH2=CH—R—CH=CH2, are normally tetrafunctional and therefore lead to branching and cross-linking even at relatively low yield. With certain initiators, however, 1,3-dienes such as CH2=CH—CH=CH2, butadiene, or CH2==C(CH3)—CH=CH2, isoprene, react bifunctionally to form unbranched 1,4-poly (dienes). Symmetric 1,6-dienes, and frequently also symmetric 1,5-dienes, likewise give more or less unbranched molecules. In contrast to the l,4-poly(dienes), however, the 1,6- and l,5-poly(dienes) only possess slight unsaturation. That is, intramolecular ring formation by a cyclopolymerization occurs, for example, in the 1,6-diene acrylic acid anhydride. 

The polymerization of acrylic and methacrylic anhydride is interesting because linear polymers can be obtained in contrast to the cross-linked networks usually formed from difunctional vinyl monomers [588-590]. In a cyclopolymerization reaction, alternating... 

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