Synthesis of Multiblock Polymer Containing Narrow Polydispersity Blocks

Abstract

Summary: We have developed a new strategy to prepare multiblock polymers and copolymers via one‐ or two‐step polymerization using a polymerizable cyclic trithiocarbonate (CTTC), 4,7‐diphenyl‐[1,3]dithiepane‐2‐thione. CTTC undergoes ring‐opening process to incorporate a trithiocarbonate moiety. The trithiocarbonate moiety in turn, functions as a reversible addition fragmentation chain transfer (RAFT) agent. Through this mechanism, multiblock polystyrenes and polystyrene‐block‐ poly(butyl acrylate) copolymers containing various narrow polydispersity blocks can be prepared.Integrated process of ring‐opening and RAFT polymerizations involving cyclic trithiocarbonates.magnified imageIntegrated process of ring‐opening and RAFT polymerizations involving cyclic trithiocarbonates.

Towards a Living Radical Polymerization of Styrene by Using Dithiolactone as a New Type of Mediating Agent

“…For this reason, a number of cyclic thiocarbonylthio compounds including 5-and 6-membered CTTCs were synthesized and evaluated as chain-transfer agents by our group. [6] However, our preliminary outcomes contrasted with the results reported by Hong et al [4,5] using 7-membered CTTCs. Indeed, we found that 5-and 6-membered CTTCs were inactive vis-à -vis propagating polystyryl or polybutylacrylyl radicals.…”

“…[3] Recently, Hong et al [4] reported the use of cyclic trithiocarbonates (CTTCs) as a new type of mediating agent in the radical polymerization of styrene and butyl acrylate. [5] The mechanism proposed for these cyclic agents is similar to the original RAFT mechanism for conventional trithiocarbonates, except that the fragmentation step is a ringopening reaction. Therefore, the reinitiating P n -R radical is composed of a P n tail bonded to thiocarbonylthio moieties (Scheme 1b, where Z ¼ SR').…”

Living Radical Polymerization by the RAFT Process—A First Update

“…[197,211] One method of synthesizing these involves a ring opening RAFT polymerization making use of the cyclic trithiocarbonate 106 (Scheme 16). [211] Multiblock copolymers have also been prepared from the multi-dithiocarbamate 107. [126] …”

Multiblock Copolymers of Styrene and Butyl Acrylate via Polytrithiocarbonate-Mediated RAFT Polymerization

“…In addition, RAFT polymerization with polytrithiocarbonates has already been used to prepare segmented copolymers composed of poly(N,N-dimethylacrylamide) (DMA) and poly(N-isopropylacrylamide) (NIPAM) [31], of polystyrene and poly(4-tert-butylstyrene) [32] and of a random DMA-NIPAM copolymer and poly(4-vinylpyridine) [33]. It has been shown that this strategy can also be carried out preparing the polytrithiocarbonates in situ by employing cyclic trithiocarbonates in the first polymerization [34,35]. It goes without saying that in principle also RAFT agents with other chemical groups (e.g., difunctional dithiocarbamates [36]) can be utilized.…”