Mechanism of alternating inter‐intramolecular propagation. I. Methacrylic anhydride

Abstract

The solution polymerization of methacrylic anhydride, a monomer which undergoes predominantly inter‐intramolecular propagation, shows kinetics similar to vinyl polymerization. The overall rate of polymerization is proportional to the square root of the initiator concentration and to the 3/2 power of the monomer concentration. The apparent, overall energy of activation was found to be 23.0 kcal./mole when azobisisobutyronitrile was used as the initiator. The value of Ep − Et/2 obtained is 8.0 kcal./mole. This compares with the value of Ep − Et/2 found for methacrylic acid in the same solvent (DMF) of 9.8 kcal./mole. Both values are in the range of values for other vinyl monomers. The polymer obtained from reactions carried out at monomer concentrations of 17% and lower were completely soluble, showed low amounts of residual unsaturation, and did not appear to be branching to a measureable extent. At higher monomer concentrations, gel was formed, and the polymers showed higher residual unsaturation levels. Poly(methacrylic anhydride) hydrolyzed to the polyacid did not show any enhancement in crystallinity over the polyacid prepared directly from methacrylic acid. Both show only low orders of crystalline content.

Cyclopolymerization of diepoxides

“…Since, according to the infrared spectra of tetrahydrofuran and tetrahydropyran, the five-membered cyclic ether shows greater ring strain, it is not unexpected that 1,2,4,5-diepoxypentane (11) does not produce a soluble polymer. Although little difference apparently exists between the kinetics of intra-intermolecular and inter-intermolecular propagation, 22 the difference in the frequency factor for the intramolecular and intermolecular steps would be expected to be relatively large in the formation of the somewha t strained furan ring.…”

Synthesis of Soluble Poly(methacrylic anhydride) by Radical Cyclopolymerization

“…11−14 Such monomers include methacrylic anhydride (MAA) and diacrylate anhydride (AA). 9,15,16 In particular, MAA, a 1,6-divinyl compound, is known to undergo cyclopolymerization in dilute solutions via radical polymerization to produce soluble polymers. 17,18 Butler and co-workers made significant contributions to the development of anhydride-based cyclic polymers, particularly the radical homo-and copolymerization of MAA and AA.…”

“…Anhydride-based divinyl monomers can undergo cyclopolymerization, the products of which have potential biomedical applications due to their ability to undergo surface erosion. − Such monomers include methacrylic anhydride (MAA) and diacrylate anhydride (AA). ,, In particular, MAA, a 1,6-divinyl compound, is known to undergo cyclopolymerization in dilute solutions via radical polymerization to produce soluble polymers. , Butler and co-workers made significant contributions to the development of anhydride-based cyclic polymers, particularly the radical homo- and copolymerization of MAA and AA. The main challenge in each of these systems was the relative suppression of the often-predominant cross-linking that occurs during radical polymerization of divinyl monomers under commonly used conditions. ,, In order to achieve cyclopolymers of MAA, the polymerization of this monomer needs to be controlled such that cyclopropagation is significantly greater than intermolecular propagation, which leads to cross-linking even at low conversion.…”