Tailored polymers by free radical processes

Abstract

This paper describes a versatile and effective method for the control of free radical polymerization and its use in the preparation of narrow polydispersity polymers of various architectures. Living character is conferred to conventional free radical polymerization by the addition of a thiocarbonylthio compound of general structure S=C(Z)SR, for example, S=C(Ph)SC(CH3)2Ph. The mechanism involves Reversible Addition-Fragmentation chain Transfer and, for convenience of referral, we have designated it the RAFT polymerization. The process is compatible with a very wide range of monomers including functional monomers such as acrylic acid, hydroxyethyl methacrylate, and dimethy laminoethyl methacrylate. Examples of narrow polydispersity (51.2) homopolymers, copolymers, gradient copolymers, end-functional polymers, star polymers, A-B diblock and A-B-A triblock copolymers are presented.

Living Radical Polymerization by the RAFT Process

“…[2][3][4][5][6][7][8] It is no longer a formidable task to apply radical polymerization to the synthesis of blocks, stars, or other polymers of complex architecture. New materials that have the potential of revolutionizing a large part of the polymer industry are beginning to appear.…”

“…RAFT polymerization, also devised in our laboratories, [13,14] is one of the most recent entrants in this field and arguably the most convenient and versatile. [5][6][7] In this paper, we report on the development, scope and mechanism of living radical polymerization with reversible addition-fragmentation chain transfer. The paper will emphasize research carried out at CSIRO but is augmented by the work of other groups, where appropriate, to provide a more complete picture.…”

“…[5,13] Initiation and radical-radical termination occur as in conventional radical polymerization. In the early stages of the polymerization, addition of a propagating radical (P • n ) to the thiocarbonylthio compound [RSC(Z) S, 1] followed by fragmentation of the intermediate radical gives rise to a polymeric thiocarbonylthio compound [P n S(Z)C S, 4] and a new radical (R • ).…”

“…[203] A difference between copolymers synthesized by RAFT copolymerization and those synthesized by conventional radical copolymerization is that copolymers formed by RAFT copolymerization are gradient copolymers whereas those formed by the conventional process are blends. It is possible to synthesize block polymers in a batch polymerization by taking advantage of disparate reactivity ratios between particular monomer pairs (BA-MMA, [5,7] tBA-VAc, [110] S-MAH [51,70,79,80] ). The composition can be further tailored by use of suitable monomer feed protocols.…”

“…S, [44,53] AA, [13,14] MA, [14,64,77,81] BA-b-AA, [14,77] MA-b-EA [14,77] BA, [9,14,44,77] (MMA), [44] S [9,82] 22 [9] S, [6,9,13,14,44,53,55] MA, [44,81,83,84] S-AN, [13,14] S-MMA, [14] MMA-HEMA, [13,14] BA, [9,14] MMA, [13,14,44,52,77] BzMA, [77] MMA-BA, [5] HEMA-iBMA-MMA-S, [14] DMAEMA, [6] XMA, [65,66] AM, [73] MMA-b-MAA, [14,77] MMA-...…”