Synthesis and properties of helical polystyrene derivatives with amino acid side groups

A series of polystyrene derivatives with chiral amide groups with a controlled molecular weight and narrow molecular weight distribution were synthesized by reversible addition–fragmentation chain transfer (RAFT) radical polymerization.

Tacticity control approached by visible-light induced organocobalt-mediated radical polymerization: the synthesis of crystalline poly(N,N-dimethylacrylamide) with high isotacticity

A crystalline polymer with high isotacticity, controlled molecular weight, and narrow polydispersity was synthesized via radical polymerization.

Yb(NTf2)3/HFIP induced high isotacticity in atom transfer radical polymerization of methyl methacrylate

Highly efficient Lewis acid Yb(NTf₂)₃ (1–8 mol%) for a high triad isotacticity (up to 69%) in bisoxazoline/copper mediated ATRP of MMA in HFIP is described.

Gradient helical copolymers: synthesis, chiroptical properties, thermotropic liquid crystallinity, and self-assembly in selective organic solvents

A series of novel gradient copolymers R-(−)-poly(StN-grad-C8) were synthesized through atom transfer radical copolymerization of an achiral styrenic monomer, N,N-dimethyl-4-ethenylbenzamide (M-StN), and a chiral bulky vinylterphenyl monomer, (−)-2,5-bis{4′-[(R)-sec-octyloxycarbonyl]phenyl}styrene (R-(−)-M-C8).

One-shot controlled/living copolymerization for various comonomer sequence distributions via dual radical and cationic active species from RAFT terminals

One-shot control of comonomer sequence distributions was demonstrated by dual radical and cationic copolymerization using RAFT mediator.

Stereo-, Temporal and Chemical Control through Photoactivation of Living Radical Polymerization: Synthesis of Block and Gradient Copolymers

Nature has developed efficient polymerization processes, which allow the synthesis of complex macromolecules with a perfect control of tacticity as well as molecular weight, in response to a specific stimulus. In this contribution, we report the synthesis of various stereopolymers by combining a photoactivated living polymerization, named photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) with Lewis acid mediators. We initially investigated the tolerance of two different photoredox catalysts, i.e., Ir(ppy)3 and Ru(bpy)3, in the presence of a Lewis acid, i.e., Y(OTf)3 and Yb(OTf)3, to mediate the polymerization of N,N-dimethyl acrylamide (DMAA). An excellent control of tacticity as well as molecular weight and dispersity was observed when Ir(ppy)3 and Y(OTf)3 were employed in a methanol/toluene mixture, while no polymerization or poor control was observed with Ru(bpy)3. In comparison to a thermal system, a lower amount of Y(OTf)3 was required to achieve good control over the tacticity. Taking advantage of the temporal control inherent in our system, we were able to design complex macromolecular architectures, such as atactic block-isotactic and isotactic-block-atactic polymers in a one-pot polymerization approach. Furthermore, we discovered that we could modulate the degree of tacticity through a chemical stimulus, by varying [DMSO]0/[Y(OTf)3]0 ratio from 0 to 30 during the polymerization. The stereochemical control afforded by the addition of a low amount of DMSO in conjunction with the inherent temporal control enabled the synthesis of stereogradient polymer consisting of five different stereoblocks in one-pot polymerization.

Direct Mechanistic Transformations from Isotactic or Syndiotactic Living Anionic Polymerizations of Methyl Methacrylate into Metal-Catalyzed Living Radical Polymerizations

The mechanistic transformations from living anionic polymerizations into living radical polymerizations were examined after halogenating the growing terminal during the stereospecific living anionic polymerization of methyl methacrylate (MMA), directly forming a macroinitiator with a covalent carbon-halogen terminal for subsequent transition metal-catalyzed living radical polymerizations. The quantitative halogenation of the living isotactic or syndiotactic PMMA anion, prepared using tBuMgBr in toluene or diphenylhexyllithium (DPHLi) in THF, respectively, was achieved using CCl₃Br or CCl₄ as a halogen source in the presence of strong Lewis bases, such as 1,8-diazabicyclo[5.4.0]undec-7-ene, to generate stereoregular PMMA with a C-X (X = Br or Cl) bond. The halogenated terminal was then transformed into the radical species through a one-electron redox reaction of the ruthenium catalysts to allow the living radical polymerization of styrene or MMA, resulting in block copolymers that consisted of stereoregular PMMA and polystyrene segments or stereoblock PMMAs.

Living Radical Polymerization by the RAFT Process – A Third Update

This paper provides a third update to the review of reversible deactivation radical polymerization (RDRP) achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition-fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669) and the second in December 2009 (Aust. J. Chem. 2009, 62, 1402). This review cites over 700 publications that appeared during the period mid 2009 to early 2012 covering various aspects of RAFT polymerization which include reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses, and a diverse range of applications. This period has witnessed further significant developments, particularly in the areas of novel RAFT agents, techniques for end-group transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.