Radical displacement as a termination reaction in allyl ester polymerization

Reassessment of Free-Radical Polymerization Mechanism of Allyl Acetate Based on End-Group Determination of Resulting Oligomers by MALDI-TOF-MS Spectrometry

“…17 Thus, a terminal allyl group characteristic of L-series, be introduced by a following alternative chain termination involving -scission of growing polymer radical through addition-fragmentation transfer, in addition to a well-known degradative monomer chain transfer, although the benzoyloxy and cyanoisopropyl groups as the initial end-groups would be generated by the thermal decomposition of BPO and AIBN as the initiators.…”

“…On the other hand, Sakurada 8,9 and Gaylord 16 have pointed out that although the degradative monomer chain transfer is quite usual in allyl polymerization, monomeric allyl radicals also have an ability of adding monomer, and thus of continuing the chain reaction, referred to as ''effective monomer chain transfer.'' Furthermore, Gaylord 17 reported the radical displacement as a chainend forming reaction by effective monomer chain transfer, i.e., -scission of growing polymer radical through addition-fragmentation transfer as is discussed later, the product radical being active enough to initiate a new polymer chain.…”

Predominant methyl radical initiation preceded by β-scission of alkoxy radicals in allyl polymerization with organic peroxide initiators at elevated temperatures

“…24,[29][30][31][32] However, appreciable I-and J-series peaks were not observed in ABz polymerization at 80 1C, although weak peaks were observed at 140 1C (see Figure 2b). The result shown in Equation 8 could be enhanced at elevated temperatures and at a lower monomer concentration.…”

“…28 Even in allyl polymerization, the formation of oligomers with a terminal allyl group may be observed as a result of the occurrence of b-scission of growing polymer radicals, although Gaylord et al 24 reported the b-scission of growing polymer radicals through additionfragmentation transfer in the polymerization of AAc. Thus, a terminal allyl group characteristic of the I-series (15.03 + (162.19n + 22.98 (Na + ))+41.07) (poly(ABz)s; CH 3 -(CH 2 -CH(CH 2 OCOC 6 H 5 )) n -CH 2 CH¼CH 2 ) and J-series (161.18 + (162.19n + 22.98 (Na + )) + 41.07) (poly(ABz)s; C 6 H 5 COOCH¼CHCH 2 -(CH 2 -CH(CH 2 O-COC 6 H 5 )) n -CH 2 CH¼CH 2 ) could be introduced by the following chain termination involving b-scission of growing polymer radicals through addition-fragmentation transfer:…”

“…This will be discussed below in connection with the b-scission of growing polymer radicals through addition-fragmentation transfer, which leads to the formation of oligomers with a terminal allyl group. 24 Allylic hydrogen abstraction from the ABz monomer by cumyloxy radical In the polymerization of ABz with DCPO, the cumyloxy radical generated may add to the double bond of ABz, abstract allylic hydrogen from ABz to afford monomeric allyl radical, and undergo b-scission to yield a methyl radical and acetophenone as shown in Equation (2). The aforementioned results show that the cumyloxy radical added little directly to the double bond.…”