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This is an example of a controlled/living cationic polymerization. Note that the "termination" step has been placed in equilibrium with an "initiation" step in either direction. Nu: is a weak nucleophile that can reversibly leave, while the MXn is a weak Lewis acid M bound to a halogen X to generate the carbocation.
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.
Taking star polymers as an example, RAFT differs from other forms of living radical polymerization techniques in that either the R- or Z-group may form the core of the star (See Figure 10). While utilizing the R-group as the core results in similar structures found using ATRP or NMP, the ability to use the Z-group as the core makes RAFT unique.
Living anionic polymerization is a living polymerization technique involving an anionic propagating species. Living anionic polymerization was demonstrated by Szwarc and co workers in 1956. Their initial work was based on the polymerization of styrene and dienes.
Living cationic polymerization is a living polymerization technique involving cationic propagating species. [1] [2] It enables the synthesis of very well defined polymers (low molar mass distribution) and of polymers with unusual architecture such as star polymers and block copolymers and living cationic polymerization is therefore as such of commercial and academic interest.
A special case of chain-growth polymerization leads to living polymerization. Ziegler–Natta polymerization allows considerable control of polymer branching. Polymerization of ethylene. Diverse methods are employed to manipulate the initiation, propagation, and termination rates during chain polymerization.
Also known as living radical polymerization, controlled radical polymerization, reversible deactivation radical polymerization (RDRP) relies on completely pure reactions, preventing termination caused by impurities. Because these polymerizations stop only when there is no more monomer, polymerization can continue upon the addition of more monomer.
A variety of techniques may be employed for the synthesis of a polymeric material with a range of architectures, for example living polymerization. Chain length A common means of expressing the length of a chain is the degree of polymerization , which quantifies the number of monomers incorporated into the chain.