Controlled synthesis of polyacrylonitrile via reversible addition-fragmentation chain-transfer pseudoliving radical polymerization and its thermal behavior

Specific features of the copolymerization of acrylonitrile and acrylamide in the presence of low-molecular-mass and polymeric trithiocarbonates and properties of the obtained copolymers

“…In the presence of trithiocarbonates in DMSO solutions, this process proceeds via a pseudo living mechanism, giv ing rise to the formation of a relatively narrowly dis perse PAN with a molecular mass up to 50 × 10 3 . In this case, the reactions of thermal cyclization and polyconjugated structure formation proceed at lower temperatures than those in PAN obtained in the absence of RAFT agents [13][14][15].…”

“…The obtained data unambiguously point to low values of efficiency of polymeric RAFT agents in polymerization. This result was extremely unex pected because PAN obtained in DMSO in the pres ence of trithiocarbonates and added to a fresh por tion of the monomer and initiator is able to resume a pseudo living process [13,14] and, according to lit erature data, the same ability is characteristic of poly acrylamide during polymerization of N,N dimethyl acrylamide in aqueous salt solutions [26]. It may be assumed that the observed deviation from a pseudo living mechanism in the case of use of copolymer RAFT agents is due to side reactions.…”

“…The polydispersity coefficients of the copolymers undergo practically no changes during the polymerization process, being 1.6-1.7 and The unambiguous evidence for a "living" chain mechanism is the ability of the forming polymer isolated from the reaction medium and added to a new portion of the monomer and initiator to partic ipate in the reversible chain transfer reaction [12]. We showed earlier that PAN synthesized under the action of both BTC and MMATC is an efficient RAFT agent for the polymerization of monomeric AN [13]. It was natural to expect that the obtained copolymers would possess the same property, despite the fact that their polydispersion coeffi cients were relatively high for RAFT processes.…”

“…We showed earlier [13,14] that reversible addition fragmentation chain transfer (RAFT) polymerization may be used to control the molecular mass character istics of PAN as well as its thermal behavior. In the presence of trithiocarbonates in DMSO solutions, this process proceeds via a pseudo living mechanism, giv ing rise to the formation of a relatively narrowly dis perse PAN with a molecular mass up to 50 × 10 3 .…”

“…As the RAFT agents R-S-C(=S)-S-R, dibenzyltrithiocarbonate (where R = CH 2 C 6 H 5 , BTC), S,S' bis (methyl 2 propi onate)trithiocarbonate (R = CH(CH 3 )(COOCH 3 ), MATC), and S,S' bis (methyl 2 isobutyrate)trithio carbonate (R = C(CH 3 ) 2 (COOCH 3 ), MMATC) were synthesized via known procedures and characterized via the NMR method as described earlier [13].…”