One‐step synthesis of block copolymers using a hydroxyl‐functionalized trithiocarbonate RAFT agent as a dual initiator for RAFT polymerization and ROP

Abstract

A range of well-defined block copolymers were synthesized using 4-cyano-4-(dodecylsulfanylthiocarbonyl)sulfanylpentanol (CDP) as a dual initiator for reversible additionfragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP) in a one-step process. Styrene, (meth)acrylate, and acrylamide monomers were polymerized in a controlled manner for one block composed of vinyl monomers, and d-valerolactone (VL), e-caprolactone (CL), trimethylene carbonate (TMC), and L-lactide (LA) were used for the other block composed of cyclic monomers. Diphenyl phosphate was used as a catalyst for the ROP of VL, CL, and TMC, and 4-dimethyamino pyridine for the ROP of LA. These catalysts did not interfere with RAFT polymerization and the synthesis of various block copolymers proceeded in a controlled manner. CDP was found to be a very useful dual initiator for a one-step synthesis of various block copolymers by a combination of RAFT polymerization and ROP. V C 2012 Wiley Periodicals, Inc. J.

Controlled One‐Pot Synthesis of Polystyrene‐block‐Polycaprolactone Copolymers by Simultaneous RAFT and ROP

“…Li et al devised a synthetic method consisting of simultaneous RAFT and ROP, of styrene and lactide, respectively, to prepare a diblock macromonomer that was subsequently used in a ring‐opening metathesis polymerization “grafting through” reaction to produce double‐brush copolymers. Recently, Youk's group reported the successful one‐pot synthesis of poly(alkyl methacrylate)‐ block ‐polyester and poly(vinylpyrrolidone)‐ block ‐polyester copolymers …”

“…These straightforward strategies were facilitated by hydroxyl‐functional molecules that worked concomitantly as a chain transfer agent (CTA) for RAFT and co‐initiator for ROP. However, there is a fundamental difference between the approaches of Howdle and co‐workers and Li et al and Youk and co‐workers that arises from the addition–fragmentation mechanism; in the former case, the CTA was 2‐(benzylsulfanylthiocarbonylsulfanyl)ethanol (1), of which the alcohol function is part of the Z activating group, whereas the free radical leaving group R is not involved in the ROP. As a consequence, the segments of an AB diblock copolymer will be covalently bound by a trithiocarbonate group situated between A and B. Alternatively, in the synthetic methods of Li and Youk the co‐initiator for ROP is attached to the leaving group R, thus leaving the main CTA moiety at the chain end of the RAFT polymer.…”

One-step synthesis of poly(2-oxazoline)-based amphiphilic block copolymers using a dual initiator for RAFT polymerization and CROP

“…On the other hand, a gradual increase in PDI with increasing reaction time was observed, which was assumed to be due to termination and/or chain transfer reactions in the CROP of MeOx [22][23][24] because the RAFT polymerization of MMA using CDP was reported to be very successful [2]. Table 1 lists the one-step synthesis results of the PMMA-b-PMeOx block copolymer using CDPS at various monomers feed ratios at 60 °C for 18 h. At all feed ratios, PMMA-bPMeOx block copolymers with narrow MW distributions were obtained.…”

“…4-Cyano-4-(dodecylsulfanylthiocarbonyl)sulfanylpentanol (CDP) was first synthesized as described elsewhere [2]. CDP (3 g, 7.69 mmol) was dissolved in 30 mL of anhydrous MC and cooled in an ice bath.…”

“…Recent studies have reported the synthesis of amphiphilic diblock copolymers using dual initiators for reversible addition-fragmentation chain transfer (RAFT) polymerization of a vinyl monomer and ring-opening polymerization (ROP) of a cyclic monomer in an one-step or one-pot procedure [1][2][3][4][5]. The block derived from the vinyl monomer was hydrophilic and the other block derived from the cyclic monomer was hydrophobic.…”