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Propagation proceeds by addition of monomer to the active species, i.e. the carbenium ion. The monomer is added to the growing chain in a head-to-tail fashion; in the process, the cationic end group is regenerated to allow for the next round of monomer addition. [6] General propagation pathway
In both anionic and cationic polymerization, each charged chain end (negative and positive, respectively) is matched by a counterion of opposite charge that originates from the initiator. Because of the charge stability necessary in ionic polymerization, monomers which may be polymerized by this method are few compared to those available for ...
In polymer chemistry, anionic addition polymerization is a form of chain-growth polymerization or addition polymerization that involves the polymerization of monomers initiated with anions. The type of reaction has many manifestations, but traditionally vinyl monomers are used.
It can be further divided into anionic polymerization and cationic polymerization. Ionic polymerization generates many polymers used in daily life, such as butyl rubber, polyisobutylene, polyphenylene, polyoxymethylene, polysiloxane, polyethylene oxide, high density polyethylene, isotactic polypropylene, butadiene rubber, etc. Living anionic ...
The mechanism is affected by the stability of the resulting cationic species. For example, if the atom bearing the positive charge is stabilized by electron-donating groups, polymerization will proceed by the S N 1 mechanism. [20] The cationic species is a heteroatom and the chain grows by the addition of cyclic monomers thereby opening the ...
In chain-growth (or chain) polymerization, the only chain-extension reaction step is the addition of a monomer to a growing chain with an active center such as a free radical, cation, or anion. Once the growth of a chain is initiated by formation of an active center, chain propagation is usually rapid by addition of a sequence of monomers.
The head of an ionic surfactant carries a net positive, or negative, charge. If the charge is negative, the surfactant is more specifically called anionic; if the charge is positive, it is called cationic. If a surfactant contains a head with two oppositely charged groups, it is termed zwitterionic, or amphoteric. Commonly encountered ...
In polymer chemistry, chain transfer is a polymerization reaction by which the activity of a growing polymer chain is transferred to another molecule: [1] [2] + + where • is the active center, P is the initial polymer chain, X is the end group, and R is the substituent to which the active center is transferred.