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While this does create a radical on the affected monomer, resonance stabilization of this radical discourages further propagation (Figure 20). [2] Figure 20: Chain transfer from polypropylene to monomer. To initiator: a polymer chain reacts with an initiator, which terminates that polymer chain, but creates a new radical initiator (Figure 21 ...
Propagation: Propagating radical chains of length n in their active (radical) form, P n •, add to monomer, M, to form longer propagating radicals, P n+1 •. RAFT pre-equilibrium: A polymeric radical with n monomer units (P n ) reacts with the RAFT agent to form a RAFT adduct radical.
The free radical chain reaction is sometimes referred to as the Bolland-Gee mechanism [6] [7] or the basic autoxidation scheme (BAS) [8] and was originally based on the oxidation of rubbers, [9] but remains generally accurate for many materials. It can be divided into three stages: initiation, propagation, and termination. [10]
Chain propagation (two steps) A radical abstracts a hydrogen atom from methane, leaving a primary methyl radical. The methyl radical then abstracts Cl • from Cl 2 to give the desired product and another chlorine radical. Methane chlorination: propagation The radical will then participate in another propagation reaction: the radical chain.
In chemistry, chain propagation (sometimes just referred to as propagation) is a process in which a reactive intermediate is continuously regenerated during the course of a chemical chain reaction. For example, in the chlorination of methane , there is a two-step propagation cycle involving as chain carriers a chlorine atom and a methyl radical ...
The expression ‘controlled polymerization’ is sometimes used to describe a radical or ionic polymerization in which reversible-deactivation of the chain carriers is an essential component of the mechanism and interrupts the propagation that secures control of one or more kinetic features of the polymerization or one or more structural ...
The species X is a persistent radical, or a species that can generate a stable radical, that cannot terminate with itself or propagate but can only reversibly "terminate" with the propagating radical (from the propagating polymer chain) P*. P* is a radical species that can propagate (k p) and irreversibly terminate (k t) with another P
Living free radical polymerization is a type of living polymerization where the active polymer chain end is a free radical. Several methods exist. Several methods exist. IUPAC recommends [ 1 ] to use the term " reversible-deactivation radical polymerization " instead of "living free radical polymerization", though the two terms are not synonymous.