Pursuit of reinitiation efficiency of resonance‐stabilized monomeric allyl radical generated via “degradative monomer chain transfer” in allyl polymerization

Abstract

For a deeper understanding of allyl polymerization mechanism, the reinitiation efficiency of resonance-stabilized monomeric allyl radical was pursued because in allyl polymerization it is commonly conceived that the monomeric allyl radical generated via the allylic hydrogen abstraction of growing polymer radical from monomer, i.e., ''degradative monomer chain transfer,'' has much less tendency to initiate a new polymer chain and, therefore, this monomer chain transfer is essentially a termination reaction. Based on the renewed allyl polymerization mechanism in our preceding article, the monomer chain transfer constant in the polymerization of allyl benzoate was estimated to be 2.7 Â 10 À2 at 80 C under the polymerization condition, where the coupling termination reaction of growing polymer radical with allyl radical was negligible and, concurrently, the reinitiation reaction of allyl radical was enhanced significantly. The reinitiation efficiencies of monomeric allyl radical were pursued by the dead-end polymerizations of allyl benzoate at 80, 105, and 130 C using a small amount of initiators; they increased remarkably with raised temperature. Thus, the enhanced reinitiation reactivity of allyl radical at an elevated temperature could bias the wellknown degradative monomer chain transfer characteristic of allyl polymerization toward the chain transfer in common vinyl polymerization.

Synthesis of novel copolymers obtained from acceptor/donor radical copolymerization of phosphonated allyl monomers and maleic anhydride

“…It is widely recognized that conventional radical homopolymerization of allyl monomers usually leads to low molecular weights oligomers (DP n less than 50 units); this behavior is generally ascribed to chain transfer process occurring onto the methylene group of allyl monomers, then limiting the propagation reaction 14, 15, 24. As already mentioned in the introduction part, allyl monomers are good electron‐donating monomers, and their radical copolymerizations with electron‐accepting monomers mainly afford alternated copolymers.…”

“…Free radical copolymerization of MA/ABE affords low molecular weights oligomers with rather low polydispersity values. This behavior is ascribed to predominant radical transfer onto ABE, referred to as “degradative monomer chain transfer.” Inoue et al14 have therefore estimated the chain transfer constant C m of allyl acetate of about 3.7 × 10 −2 at 80 °C. The MA/phosphonate allyl monomers free radical copolymerizations show different trend, as compared to MA/ABE copolymerization.…”

“…We also showed that, depending on both the reaction conditions and of the R substituent, the resulting polymeric species could have either hyperbranched (with high M w values) or linear structure (with low M w values). Indeed, it is well‐known that the radical homopolymerization of allyl monomers usually results in low M w oligomers, mainly due to degradative chain transfer 13–15. The weakness of the allyl CH bond arises from the high resonance stability of the allyl radical, which is too stable to reinitiate polymerization and undergoes termination by reaction with a propagating radical 11…”

PMMA-supported near-infrared (NIR) luminescent hybrid materials doped with Zn2Ln2-arrayed Schiff-base complexes

“…As shown in Figure 1S, These results, incomparable to photodimerization of 4,4'-bpe-bridged complexes by [2+2] cycloaddition [14], should be attributable to degradative chain transfer [18] of the central C=C double bond in free or coordinated 4,4'-bpe, from which lower reactivity of the resonance-stabilized monomeric radical formed from these two conjugated monomers than that of MMA leads much less tendency to initiate a new polymer chain. It is worth noting that 1 H NMR analysis of PMMA@1 further shows the lower molar ratio of 77:1 than the initial feed molar ratio (100:1) of MMA with 1, which should be due to the loss of MMA from oligometric PMMA.…”

Structure–Property Relationship of Thin Plasma Deposited Poly(allyl alcohol) Films

“…First experiments to plasma polymerize AAl were carried out by Denaro et al [3]. They investigated the glow discharge polymerization of different organic vapours.…”