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Catalytic chain transfer polymerization is not a strictly living form of polymerization. Yet it figures significantly in the development of later forms of living free radical polymerization. Discovered in the late 1970s in the USSR it was found that cobalt porphyrins were able to reduce the molecular weight during polymerization of methacrylates.
The second strategy is based on a degenerative transfer (DT) of the propagating radical between transfer agent that acts as a dormant species (i.e. Reversible addition−fragmentation chain-transfer polymerization). The DT based CRP's follow the conventional kinetics of radical polymerization, that is slow initiation and fast termination, but ...
Chain transfer can be either introduced deliberately into a polymerization (by use of a chain transfer agent) or it may be an unavoidable side-reaction with various components of the polymerization. Chain transfer reactions occur in most forms of addition polymerization including radical polymerization, ring-opening polymerization, coordination ...
The essential feature is that the product of chain transfer is also a chain transfer agent with similar activity to the precursor transfer agent. [5] 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 ...
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 ...
In polymer chemistry, degenerative chain transfer (also called degenerate chain transfer) is a process that can occur in a radical polymerization where the active site is transferred from one site along the polymer chain to another site, without changing the active site's reactivity (hence the term "degenerate," signifying that the pre- and post-transfer active sites have the same energy or ...
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.
One of the major drawbacks of the process is that catalytic chain transfer polymerization does not produce macromonomers of use in free radical polymerizations, but instead produces addition-fragmentation agents. When a growing polymer chain reacts with the addition fragmentation agent the radical end-group attacks the vinyl bond and forms a bond.