Controlled synthesis of multiblock copolymers by pseudoliving radical polymerization via the reversible addition-fragmentation chain-transfer mechanism

Abstract

With the use of two classes of reversible addition fragmentation chain transfer agentsdithiobenzoates and trithiocarbonates-multiblock copolymers based on styrene and n butyl acrylate, which are the best studied monomers in these processes, are synthesized. It is shown that the polymers containing dithiobenzoate and trithiocarbonate groups are highly efficient for the synthesis of block copolymers, which is independent of the number of stages at which the polymeric RAFT agents are used in polymerization: In all cases, the polymeric RAFT agent is fully consumed in the polymerization of the "alien" monomer. The mechanism governing chain formation during the synthesis of multiblock copolymers, that is, the character of monomer insertion into the polymer chain, via one or both ends, is studied. It is found that the order of monomer loading determines the ratio of chains growing through one or two ends. The thermal stability of amphiphilic multiblock copolymers, their solubility in various solvents, and self organizing ability are inves tigated.

Synthesis of amphiphilic copolymers based on acrylic acid, fluoroalkyl acrylates and n-butyl acrylate in organic, aqueous–organic, and aqueous media via RAFT polymerization

“…Hence, the formation of triblock copolymers proceeds via the insertion of new monomers between the trithiocarbonate group and the terminal monomer unit of the attached polymeric substituent. 13,14,62 Fig . 5b and c show the transformation of the MWDs with conversion for the products of the copolymerization of BA and HFBA (at a molar ratio of 80 : 20) in the presence of Pol-A (b) and Cop-H5 (c).…”

Polymerizations by RAFT: Developments of the Technique and Its Application in the Synthesis of Tailored (Co)polymers

“…Classical RAFT controlled polymerizations have been employed extensively for synthesizing such multiblock copolymers. [ 179–189 ] In 2013, Perrier and co‐workers reported for the first time a RAFT controlled synthetic route that could provide multiblock copolymers combining precisely defined, high‐order structures of well‐defined molecular weight distributions with a wide range of functional groups. [ 190 ] This simple and scalable synthesis was based on a one‐pot, sequential polymerization at very high yields (over 99%).…”

Liquid crystalline side-chain triblock copolymers consisting of a nematic central subblock edged by photochromic azobenzene-containing fragments: their synthesis, structure and photooptical behaviour

“…Aiming at the controlled synthesis of LC symmetrical triblock copolymers we have applied RAFT polymerization using bifunctional symmetrical trithiocarbonate BMITC, the latter has been already successfully used for the RAFT polymerization of various vinyl monomers (e.g., acrylates, styrene, vinyl acetate, and acrylonitrile). 64 The reversible chain transfer reactions occurring in the polymerization mediated by symmetric trithiocarbonates are as follows:…”