1. A Commercial RAFT Agent with Broad Applicability
BM1565
Ivan Martinez-Botella, James Gardiner, Thomas M. Kohl, Ashley L. Cornell, Christian H. Hornung, John Tsanaktsidis
CSIRO Manufacturing
The latest RAFT Agent made commercially available: BM1565 (2-cyanobutan-2-yl 4-chloro-3,5-dimethyl-1H-pyrazole-1-carbodithioate) has proven to be the most versatile of the low odour, low cost RAFT Agents accessible in large quantities.
Background
RAFT (Reversible Addition-Fragmentation chain Transfer) polymerisation technology has the ability to produce polymers having a well-defined molecular architecture, a predetermined molecular weight and low polydispersity (Đ).1
Results
Homopolymers
Table 2: RAFT polymerisations of MAM and LAM in presence of different RAFT Agents. All experiments were conducted with microwave heating at 100 °C. Initiator = 1,1’-azobis(-1-cyanocyclohexane).
Polystyrene was synthesised in the absence of solvent or initiator. BM1565 provided excellent control over molecular weight and polydispersity.
Recently, new methods of synthesis have been developed to provide affordable RAFT Agents with low odour and high purity in gram to metric tonne quantities.
Table 3: RAFT polymerisation of styrene under neat conditions All Experiments were conducted with microwave heating.
Copolymers
Table 4: RAFT polymerisations of a mixture of two monomers in presence of BM1565. All experiments were conducted with microwave heating at 100 °C. Initiator = 1,1’-azobis(-1-cyanocyclohexane).
MAM-LAM Block copolymers
Table 5: Block copolymers prepared with BM1565 as quasi-blocks by addition of the second monomer and additional initiator and solvent to the reaction mixture without isolation of the first block. All Experiments were conducted with microwave heating at 100 °C. Initiator = 1,1’-azobis(-1-cyanocyclohexane).
Table 1: RAFT Agent Availability and Monomer Compatibility (Boron Molecular Pty Ltd )
The dithiocarbamate RAFT Agents are capable of controlling the polymerisation of both types of monomers, more-activated monomers (MAMs) and less-activated monomers (LAMs) toward RAFT polymerisation.2
Homopolymers, copolymers and block copolymers with low polydispersities were synthesised in the presence of BM1565 using MAMs (i.e. styrene (S), N,N-dimethylacrylamide (DMA), methyl methacrylate (MMA) and methyl acrylate (MA)); and LAMs (i.e. vinyl acetate (VA)).
Figure 1: Molar mass distributions for poly(DMA) macro-RAFT Agent prepared with BM1565 ( ̶̶̶̶ ) and the derived poly(DMA)-block-poly(MA) ( - - ). Table 5, first entry.
Figure 2: Molar mass distributions for poly(DMA) macro-RAFT Agent prepared with BM1565 ( ̶̶̶̶ ) and the derived poly(DMA)-block-poly(VA) ( - - ). Table 5, second entry.
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References
[1] J. Chiefari, Y. K.. Chong, F. Ercole, J. Krstina, J. Jeffery, T. P. T Le, R. T. A. Mayadunne, G. F. Meijs, C. L. Moad, G. Moad, E. Rizzardo, S. H. Thang, Macromolecules, 1998, 31(16), 5559.
[2] J. Gardiner, I. Martinez-Botella, J. Tsanaktsidis, G. Moad, Polym. Chem., 2016, 7,