- Addition polymerization
where n is the
degree of polymerization.
The main characteristics are:
* polymerisation process takes place in three distinct steps:
# chain initiation, usually by means of an
initiatorwhich starts the chemical process. Typical initiators include any organic compound with a labile group: e.g. azo (-N=N-), disulfide (-S-S-), or peroxide (-O-O-). Two examples are benzoyl peroxideand AIBN.
chain termination, which occurs either by combination or disproportionation. Termination, in radical polymerisation, is when the free radicals combine and is the end of the polymerisation process.
* some side reactions may occur, such as: chain transfer to monomer, chain transfer to solvent, and chain transfer to polymer.
* unlike condensation polymerisation (also known as
** high molecular weight polymer is formed at low conversion
** no small molecules, such as H2O, are eliminated in this process
* new monomer adds on the growing polymer chain via the reactive active centre which can be a
free radicalin free radical addition polymerisation
carbocationin cationic addition polymerisation
carbanionin anionic addition polymerisation
organometalliccomplex in coordination polymerisation
* the monomer molecule can be a
unsaturated compoundlike ethyleneor acetylenewhich make them reactive, see vinyl polymer
Alicyclic compound, see ring-opening polymerisation
* given special reactants and reaction conditions an addition polymerization can be considered a
* above a certain
ceiling temperature, no polymerisation occurs.
benzoyl peroxideis a radical initiatorfor the free radical addition polymerisation of styreneto produce polystyrene.
Aluminium chlorideis an initiator for the cationic addition polymerisation of isobutyleneto form isobutyl synthetic rubber.
Wikimedia Foundation. 2010.
Look at other dictionaries:
addition polymerization — grandininė polimerizacija statusas T sritis chemija apibrėžtis Grandininė reakcija tarp aktyviojo centro ir monomero, kurios metu susidaro makromolekulė. atitikmenys: angl. addition polymerization; chain polymerization rus. цепная полимеризация … Chemijos terminų aiškinamasis žodynas
addition polymerization — noun : polymerization without formation of a by product distinguished from condensation polymerization * * * Chem. See under polymerization (def. 2) … Useful english dictionary
addition polymerization — Chem. See under polymerization (def. 2). * * * … Universalium
Anionic addition polymerization — An anionic addition polymerization of vinyl monomers is an addition polymerization initiated by a strong base and anion, such as an alkali amide, or an organometallic compound, such as n butyllithium. A nucleophilic carbanion is formed containing … Wikipedia
Polymerization — An example of alkene polymerization, in which each Styrene monomer unit s double bond reforms as a single bond with another styrene monomer and forms polystyrene. In polymer chemistry, polymerization is a process of reacting monomer molecules… … Wikipedia
polymerization — /peuh lim euhr euh zay sheuhn, pol euh meuhr /, n. Chem. 1. the act or process of forming a polymer or polymeric compound. 2. the combination of many like or unlike molecules to form a more complex product of higher molecular weight, with… … Universalium
Addition polymer — An addition polymer is a polymer which is formed by an addition reaction, where many monomers bond together via rearrangement of bonds without the loss of any atom or molecule. This is in contrast to a condensation polymer which is formed by a… … Wikipedia
Addition reaction — An addition reaction, in chemistry, is in its simplest terms an organic reaction where two or more molecules combine to form a larger one.There are two main types of polar addition reactions: * Electrophilic addition * Nucleophilic addition Other … Wikipedia
Living polymerization — In polymer chemistry, living polymerization is a form of addition polymerization where the ability of a growing polymer chain to terminate has been removed Ref|1. This can be accomplished in a variety of ways. Chain termination and chain transfer … Wikipedia
Ring-opening polymerization — In polymer chemistry, ring opening polymerization is a form of addition polymerization, in which the terminal end of a polymer acts as a reactive center, where further cyclic monomers join to form a larger polymer chain through ionic propagation … Wikipedia