Role of initiator‐transfer agent‐terminator (iniferter) in radical polymerizations: Polymer design by organic disulfides as iniferters

Abstract

Polymer formations by radical polymerization of vinyl monomer (M) initiated by an initiator (R-R') are expressed by Eq. (I), if no chain transfer reaction occurs and the termination proceeds via a recombination of the growing radicals.Therefore, radical polymerization may simply be considered as a successive insertion reaction of the monomer molecules into the R-R' bond of the initiator leading to a polymer with two initiator fragments bonded at its both ends. The radical polymerization of styrene initiated by 2,2 '-azoisobutyronitrile is only an example close to such a case'). The above assumptions are, however, generally not realized, and thus the number of initiator fragments per polymer molecule is always less than 2.If the initiator used has a high reactivity for a chain transfer to the initiator, or a part of the radical produced by the initiator easily undergoes primary radical termination, a polymer with two initiator fragments, similar to Eq. (l), can be obtained [Eq. (211. R-R'+nM + R+M+R'(2) Therefore, the choice of such initiators in vinyl polymerization opens the possibility of synthesizing easily monofuntional or a,o-bifunctional oligomers and polymers via radical mechanism, and thus designing a polymer structure by radical polymerization.Thus, we may call such initiators initiator-tranuer agent (inifer), and/or initiatorterminator (initer). Since it is difficult to distinguish between "inifer" and "initer" for usual radical initiators, however, we propose to call them initiator-tranuer agentterminator (iniferter). The concept of "inifer" in cationic polymerization has already been proposed by Kennedy2).When iniferters such as phenylazotriphenylmethane, phenylphenylazosulfide, 1,3diphenyltriazene, alkyl perbenzoates, monosulfides etc., are used in radical polymerization, monofunctional polymers are produced, as shown in Eq.(3), as an example.

Design of Nonionic Surfactants for Supercritical Carbon Dioxide

“…We synthesized PS-b-PFOA diblock copolymers ( Fig. 1) with the "iniferter" technique developed by Otsu (18)(19)(20). We first synthesized the lyophobic PS segment of the surfactant by using tetraethylthiuram disulfide as the initiator.…”

Developments in CO2 research

“…Controlled free-radical polymerizations were used to synthesize most of the fluoroacrylates via iniferter [16] and atom-transfer radical polymerization (ATRP) [17] techniques. The CO 2 -phobic block has been synthesized to include polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(tert-butyl acrylate) (PTBA), poly(vinyl acetate) (PVAc), and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) [18][19][20].…”

Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB) n block copolymers

“…The term 'iniferter' is used for free radical initiators with simultaneous chain transfer and terminating properties, thereby providing a pseudo-living polymerization (13)(14)(15)(16). This technique enabled us to synthesize a novel type of multiblock copolymer, consisting of alternating polybutadiene (PB) and (styrene-eo-acrylonitrile) (SAN) blocks (17,18), or alternating polybutadiene and (styrene-eo-maleic anhydride) (SMA) blocks (19).…”