Radical Ring-Opening Copolymerization of 2-Methylene 1,3-Dioxepane and Methyl Methacrylate:  Experiments Originally Designed To Probe the Origin of the Penultimate Unit Effect

Abstract

Pulsed-laser polymerization experiments were conducted on the copolymerization of 2-methylene 1,3-dioxepane (MDO) and methyl methacrylate (MMA) at 40 °C. Reactivity ratios, based on the terminal model, were determined from copolymer compositional analyses as r MDO = 0.057 and r MMA = 34.12. The average propagation rate coefficients, 〈k p〉, were determined for a number of feed compositions ranging from an MDO mole fraction of 0 to 0.916. It was not possible to obtain a 〈k p〉 value for the homopolymerization of MDO as the PLP experiment was compromised by high chain transfer rates to polymer and monomer. The data were fitted to a number of copolymerization models, viz. the terminal and the explicit and implicit penultimate unit models and the bootstrap solvent dependence model. It was found that the terminal and penultimate unit models for copolymerization could not adequately describe the experimental results. A fit to a bootstrap model was successful, but the values obtained indicated a very large, unprecedented, partitioning effect.

Synthesis of Degradable Materials Based on Caprolactone and Vinyl Acetate Units Using Radical Chemistry

“…9 Davis et al have reported copolymerization parameters for copolymerization of MDO with MMA at 40 C as r MDO ¼ 0:057 and r MMA ¼ 34:12 thereby showing the low tendency of cyclic ketene acetals to copolymerize with vinyl monomers. 10 In this work we show very good copolymerizability of MDO with VAc which is due to the similarity in monomer structures in terms of nucleophilic double bond and stability of growing radicals. We calculated Q (monomer reactivity) and e (monomer polarity) values for MDO using a well known Alfrey-Price equation.…”

“…is reported by us 11-18 and others. 10,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The main problem during the copolymerization is the huge reactivity difference between the CKA and the vinyl monomers leading to either low molecular weight homo vinyl polymers without ester linkages or copolymers incorporating only low amounts of the comonomers with block structure, incomplete ring-opening or no ring-opening at all.Keeping in view our broad aim of making new degradable materials with new properties based on the conventional plastics, here an attempt has been made to study the copolymerization behaviour of vinyl acetate (VAc) and MDO under conventional radical polymerization conditions. The resulting materials depending upon the glass transition temperatures could be proposed for further studies as degradable gums, coating materials, adhesives etc.…”

“…[1][2][3][4][5][6][7] A less known route to the formation of poly(caprolactone), first shown by Bailey et al 8 and later followed by some others, 9,10 is by radical ringopening polymerization of 2-methylene-1,3-dioxepane (MDO). 2-methylene-1,3-dioxepane is an interesting cyclic ketene acetal monomer giving poly("-caprolactone) (PCL), on the radical-ring-opening homopolymerization (RROP) and can introduce ester groups onto the vinyl polymer backbones during copolymerizations with vinyl monomers.…”

“…is reported by us [11][12][13][14][15][16][17][18] and others. 10,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The main problem during the copolymerization is the huge reactivity difference between the CKA and the vinyl monomers leading to either low molecular weight homo vinyl polymers without ester linkages or copolymers incorporating only low amounts of the comonomers with block structure, incomplete ring-opening or no ring-opening at all.…”

Precipitation Polymerization of 2-Methylene-1,3-dioxepane in Supercritical Carbon Dioxide

“…MDOP also proceed with 100% ring opening for polymer and easily copolymerize with vinylic monomers such as styrene, N-isopropylacrylamide, methyl acrylate and methyl methacrylate, and so on using AIBN as a thermal radical initiator. [9][10][11][12] These resulting copolymers have degradable caprolactone (CL) units in their molecular backbones.…”