Novel Difunctional Reversible Addition Fragmentation Chain Transfer (RAFT) Agent for the Synthesis of Telechelic and ABA Triblock Methacrylate and Acrylate Copolymers

Abstract

The design of a novel difunctional chain transfer agent (CTA) based on the propagating core (R group) approach is detailed. Successful synthesis of ABA block copolymers of poly(butyl methacrylate)-b-poly(methyl methacrylate)-b-poly(butyl methacrylate) and poly(butyl acrylate)-b-poly(methyl methacrylate)-b-poly(butyl acrylate) with targeted molecular weight and polydisperity indices in the range 1.2−1.4 is reported. The effect of free radical initiator concentration with respect to CTA concentration on block efficiency is investigated and lower concentrations were found to increase reaction time, but significantly reduce termination reactions. The consequence of difunctionality on homo and block extension polymerizations is discussed, with the polymerization of methyl and butyl methacrylate being more controlled than butyl acrylate.

Living Radical Polymerization by the RAFT Process - A Second Update

“…St [184] MMA [88] 323 [185] 40 [186] S S O O St [186] St-b-MAH [186] St-b-MAH-b-NIPAM [186] 41* [187,188] S S (MMA) [64,187,189] BA [187] EHA [188] St [190] TBAM [191] DEAM [187] DMAM [187] NAM [191] NIPAM [187,189] BA/St [192] EHA-b-MA [188] TBAM-b-NAM [191] DMAM/NAS [193] NAM-b-TBAM [191] 42* S S Ph CN MMA [194] 376 [195] 376-b-MMA [195] BA [196] MMA [189] NIPAM [189] MMA-b-NIPAM [189] MMA/283 [197] MMA/284 [197] St/2VP [198] St/348 [199] THPA-b-St [200] THPA-b-St/373 [201] 44 [202] [200] 47 [203] …”

Synthesis and characterization of diethyl-dithiocarbamic acid 2-[4-(2-diethylthiocarbamoylsulfanyl-2-phenyl-acetyl)-2,5-dioxo-piperazin-1-yl]-2-oxo-1-phenyl-ethyl ester as new reversible addition-fragmentation chain transfer agent for polymerization of ethyl methacrylate

“…[29] The chosen R group with phenylacetyl moiety is already known to be very effective in the controlled polymerization of methacrylate monomers. [30] -XCHPh group that X is carbonyl group, is suitable R group with a high fragmentation rate for methacrylate monomers. Carbonyl group acts as a suitable electron withdrawing group.…”

“…Carbonyl group acts as a suitable electron withdrawing group. [29,30] In addition, the R group increases fragmentation rate by its spatial hindrance. The new bifunctional RAFT agent has central R group containing diketopiperazine cycle and fragmentation/reinitiation occurs from two sides of RAFT agent.…”

Original approach to multiblock copolymers via reversible addition–fragmentation chain transfer polymerization

“…29 Methacrylate polymerization is one of the most challenging systems to control via the RAFT process. Indeed, steric hindrance tends to prevent the addition of a methacrylate bulky tertiary propagating radical to the thiocarbonyl thio group of the CTA.…”