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Control in RAFT polymerization (scheme 1) is achieved in a far more complicated manner than the homolytic bond formation-bond cleavage of SFRP and ATRP. The CTA for RAFT polymerization must be chosen cautiously because it has an effect on polymer length, chemical composition, rate of the reaction and the number of side reactions that may occur.
RAFT polymerization today is mainly carried out by thiocarbonylthio chain transfer agents. It was first reported by Rizzardo et al. in 1998. [6] RAFT is one of the most versatile methods of controlled radical polymerization because it is tolerant of a very wide range of functionality in the monomer and solvent, including aqueous solutions. [7]
The expression ‘controlled radical polymerization’ is sometimes used to describe a radical polymerization that is conducted in the presence of agents that lead to e.g. atom-transfer radical polymerization (ATRP), nitroxide-(aminoxyl) mediated polymerization (NMP), or reversible-addition-fragmentation chain transfer (RAFT) polymerization.
Reversible Addition-Fragmentation Chain-Transfer Polymerization (RAFT): requires a compound that can act as a reversible chain-transfer agent, such as dithio compound. [2] Stable Free Radical Polymerization (SFRP): used to synthesize linear or branched polymers with narrow molecular weight distributions and reactive end groups on each polymer ...
Living polymerization: A chain polymerization from which chain transfer and chain termination are absent.. Note: In many cases, the rate of chain initiation is fast compared with the rate of chain propagation, so that the number of kinetic-chain carriers is essentially constant throughout the polymerization.
The K ATRP value depends on the homo-cleavage energy of the alkyl halide and the redox potential of the Cu catalyst with different ligands. Given two alkyl halides (R 1-X and R 2-X) and two ligands (L 1 and L 2), there will be four combinations between different alkyl halides and ligands. Let K ij ATRP refer to the K ATRP value for R i-X and L ...
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For example, ATRP is sensitive to oxygen whereas RAFT is insensitive to oxygen; in addition, RAFT has a much greater compatibility with monomers than ATRP. [ 7 ] Radical polymerization with crosslinkers is the other in situ polymerization method, and this process leads to the formation of biomolecule-crosslinked polymer nanocapsules. [ 7 ]