SherbyNet - /page/wikibook/entry.mu

Micron Document

<!DOCTYPE html>

<title>Living polymerization</title>

</head>

Living polymerization

</h1>

</header>

In <a href="Polymer_chemistry" title="Polymer chemistry">polymer chemistry</a>, living polymerization is a form of <a href="Chain_growth_polymerization" class="mw-redirect" title="Chain growth polymerization">chain growth polymerization</a> where the ability of a growing <a href="Polymer_chain" class="mw-redirect" title="Polymer chain">polymer chain</a> to <a href="Chain_termination" title="Chain termination">terminate</a> has been removed.<a href="#cite_note-1">[1]</a><a href="#cite_note-2">[2]</a> This can be accomplished in a variety of ways. <a href="Chain_termination" title="Chain termination">Chain termination</a> and <a href="Chain_transfer_reaction" class="mw-redirect" title="Chain transfer reaction">chain transfer reactions</a> are absent and the rate of <a href="Chain_initiation" class="mw-redirect" title="Chain initiation">chain initiation</a> is also much larger than the rate of <a href="Chain_propagation" title="Chain propagation">chain propagation</a>. The result is that the polymer chains grow at a more constant <a href="Reaction_rate" title="Reaction rate">rate</a> than seen in traditional chain <a href="Polymerization" title="Polymerization">polymerization</a> and their lengths remain very similar (i.e. they have a very low <a href="Polydispersity_index" class="mw-redirect" title="Polydispersity index">polydispersity index</a>). Living polymerization is a popular method for synthesizing <a href="Block_copolymer" class="mw-redirect" title="Block copolymer">block copolymers</a> since the polymer can be synthesized in stages, each stage containing a different <a href="Monomer" title="Monomer">monomer</a>. Additional advantages are predetermined <a href="Molar_mass" title="Molar mass">molar mass</a> and control over <a href="End-group" class="mw-redirect" title="End-group">end-groups</a>.

/* start https://en.wikipedia.org/ */

.mw-parser-output .quotebox{background-color:#F9F9F9;border:1px solid #aaa;box-sizing:border-box;padding:10px;font-size:88%;max-width:100%}.mw-parser-output .quotebox.floatleft{margin:.5em 1.4em .8em 0}.mw-parser-output .quotebox.floatright{margin:.5em 0 .8em 1.4em}.mw-parser-output .quotebox.centered{overflow:hidden;position:relative;margin:.5em auto .8em auto}.mw-parser-output .quotebox.floatleft span,.mw-parser-output .quotebox.floatright span{font-style:inherit}.mw-parser-output .quotebox>blockquote{margin:0;padding:0;border-left:0;font-family:inherit;font-size:inherit}.mw-parser-output .quotebox-title{text-align:center;font-size:110%;font-weight:bold}.mw-parser-output .quotebox-quote>:first-child{margin-top:0}.mw-parser-output .quotebox-quote:last-child>:last-child{margin-bottom:0}.mw-parser-output .quotebox-quote.quoted:before{font-family:"Times New Roman",serif;font-weight:bold;font-size:large;color:gray;content:" “ ";vertical-align:-45%;line-height:0}.mw-parser-output .quotebox-quote.quoted:after{font-family:"Times New Roman",serif;font-weight:bold;font-size:large;color:gray;content:" ” ";line-height:0}.mw-parser-output .quotebox .left-aligned{text-align:left}.mw-parser-output .quotebox .right-aligned{text-align:right}.mw-parser-output .quotebox .center-aligned{text-align:center}.mw-parser-output .quotebox .quote-title,.mw-parser-output .quotebox .quotebox-quote{display:block}.mw-parser-output .quotebox cite{display:block;font-style:normal}@media screen and (max-width:640px){.mw-parser-output .quotebox{width:100%!important;margin:0 0 .8em!important;float:none!important}}

/* end https://en.wikipedia.org/ */

</style><div class="quotebox pullquote floatright" style="width:30%; ;">

<div class="quotebox-title" style=""><a href="International_Union_of_Pure_and_Applied_Chemistry" title="International Union of Pure and Applied Chemistry">IUPAC</a> definition</div>

Living polymerization: A chain polymerization from which chain transfer and chain termination are absent.

Note: In many cases, the rate of chain initiation is fast compared with the rate of chain propagation, so that the number of kinetic-chain carriers is essentially constant throughout the polymerization.<a href="#cite_note-3">[3]</a>

</blockquote>

</div>

Living polymerization is desirable because it offers precision and control in macromolecular synthesis. This is important since many of the novel/useful properties of polymers result from their microstructure and molecular weight. Since <a href="Molecular_weight" class="mw-redirect" title="Molecular weight">molecular weight</a> and <a href="Dispersity" title="Dispersity">dispersity</a> are less controlled in non-living polymerizations, this method is more desirable for materials design<a href="#cite_note-Cowie-4">[4]</a><a href="#cite_note-Principles-5">[5]</a>

In many cases, living polymerization reactions are confused or thought to be synonymous with controlled polymerizations. While these polymerization reactions are very similar, there is a distinction between the definitions of these two reactions. While living polymerizations are defined as polymerization reactions where termination or chain transfer is eliminated, controlled polymerization reactions are reactions where termination is suppressed, but not eliminated, through the introduction of a dormant state of the polymer.<a href="#cite_note-Cowie-4">[4]</a><a href="#cite_note-Principles-5">[5]</a> However, this distinction is still up for debate in the literature.

The main living polymerization techniques are:

<ul><li><a href="Living_anionic_polymerization" class="mw-redirect" title="Living anionic polymerization">Living anionic polymerization</a></li>

<li><a href="Living_cationic_polymerization" title="Living cationic polymerization">Living cationic polymerization</a></li>

<li>Living <a href="Ring-opening_metathesis_polymerization" title="Ring-opening metathesis polymerization">ring-opening metathesis polymerization</a></li>

<li><a href="Living_free_radical_polymerization" class="mw-redirect" title="Living free radical polymerization">Living free radical polymerization</a></li>

<li>Living chain-growth polycondensations</li></ul>

<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>

Living polymerization was demonstrated by <a href="Michael_Szwarc" title="Michael Szwarc">Michael Szwarc</a> in 1956 in the anionic polymerization of <a href="Styrene" title="Styrene">styrene</a> with an <a href="Alkali_metal" title="Alkali metal">alkali metal</a> / <a href="Naphthalene" title="Naphthalene">naphthalene</a> system in <a href="Tetrahydrofuran" title="Tetrahydrofuran">tetrahydrofuran</a> (THF). Szwarc showed that <a href="Electron_transfer" title="Electron transfer">electron transfer</a> occurred from <a href="Radical_anion" title="Radical anion">radical anion</a> of <a href="Naphthalene" title="Naphthalene">naphthalene</a> to <a href="Styrene" title="Styrene">styrene</a>. The initial radical anion of styrene converts to a <a href="Dianion" title="Dianion">dianion</a> (or equivalently disodio-) species, which rapidly added styrene to form a "two – ended living polymer." An important aspect of his work, Szwarc employed the <a href="Aprotic_solvent" class="mw-redirect" title="Aprotic solvent">aprotic solvent</a> <a href="Tetrahydrofuran" title="Tetrahydrofuran">tetrahydrofuran</a>, which dissolves but is otherwise unreactive toward the organometallic intermediates. After initial addition of monomer to the initiator system, the <a href="Viscosity" title="Viscosity">viscosity</a> increased (due to increased polymer chain growth), but eventually cease after depletion of monomer concentration. However, he found that addition of more monomer caused an increase in viscosity, indicating growth of the polymer chain, and thus concluded that the polymer chains had never been terminated.<a href="#cite_note-ReferenceA-6">[6]</a> This was a major step in polymer chemistry, since control over when the polymer was quenched, or terminated, was generally not a controlled step. With this discovery, the list of potential applications expanded dramatically.<a href="#cite_note-7">[7]</a>

Today, living polymerizations are used widely in the production of many types of polymers or plastics. For instance, <a href="Poly(phthalaldehyde)" title="Poly(phthalaldehyde)">poly(phthalaldehyde)</a> polymer, first developed in 1967, can be synthesized via both <a href="Living_cationic_polymerization" title="Living cationic polymerization">living cationic</a> and <a href="Living_anionic_polymerization" class="mw-redirect" title="Living anionic polymerization">living anionic</a> polymerization reactions producing both the cyclic or linear form of the polymer respectively. The approach offers control of the chemical makeup of the polymer and, thus, the structural and electronic properties of the material. This level of control rarely exists in non-living polymerization reactions.<a href="#cite_note-Principles-5">[5]</a><a href="#cite_note-McNeil_1-8">[8]</a>

<div class="mw-heading mw-heading2"><h2 id="Fast_rate_of_initiation:_low_polydispersity">Fast rate of initiation: low polydispersity</h2></div>

One of the key characteristics of a living polymerization is that the chain termination and transfer reactions are essentially eliminated from the four elementary reactions of <a href="Chain-growth_polymerization" title="Chain-growth polymerization">chain-growth polymerization</a> leaving only <a href="Initiation_(chemistry)" title="Initiation (chemistry)">initiation</a> and (chain) propagation reactions.

A key characteristic of living polymerization is that the rate of initiation (meaning the dormant chemical species generates the active chain propagating species) is much faster than the rate of chain propagation. Thus all of the chains grow at the same rate (the rate of propagation).

The high rate of initiation (together with absence of termination) results in low (or narrow) polydispersity index (PDI), an indication of the broadness in the distribution of polymer chains.<a href="#cite_note-9">[9]</a> The extended lifetime of the propagating chain allowing for co-block polymer formation and end group functionalization to be performed on the living chain. These factors also allow predictable molecular weights, expressed as the number average molecular weight (Mn). For an ideal living system, assuming efficiency for generating active species is 100%, where each initiator generates only one active species the <a href="Kinetic_chain_length" title="Kinetic chain length">Kinetic chain length</a> (average number of monomers the active species reacts with during its lifetime) at a given time can be estimated by knowing the concentration of monomer remaining. The number average molecular weight, <a href="Molar_mass_distribution#number_average_molecular_mass" title="Molar mass distribution">Mn</a>, increases linearly with percent conversion during a living polymerization

<mfrac>

<mrow>

<msub>

</mrow>

</msub>

</mrow>

<mrow>

<msub>

</mrow>

</msub>

</mrow>

</mfrac>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \ v={\frac {[M]_{0}-[M]}{[I]_{0}}}}</annotation>

</semantics>

</math><img src="./db304320640f163330c3130db03ff9691e1a8ffa.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:17.009ex; height:6.509ex;" alt="{\displaystyle \ v={\frac {[M]_{0}-[M]}{[I]_{0}}}}" loading="lazy"><a href="#cite_note-Principles-5">[5]</a></dd></dl>

<div class="mw-heading mw-heading2"><h2 id="Techniques">Techniques</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Living_anionic_polymerization">Living anionic polymerization</h3></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Living_anionic_polymerization" class="mw-redirect" title="Living anionic polymerization">Living anionic polymerization</a></div>

As early as 1936, <a href="Karl_Ziegler" title="Karl Ziegler">Karl Ziegler</a> proposed that anionic polymerization of styrene and butadiene by consecutive addition of monomer to an alkyl lithium initiator occurred without chain transfer or termination. Twenty years later, living polymerization was demonstrated by Szwarc through the <a href="Anionic_addition_polymerization" title="Anionic addition polymerization">anionic polymerization</a> of <a href="Styrene" title="Styrene">styrene</a> in <a href="THF" class="mw-redirect" title="THF">THF</a> using <a href="Sodium_naphthalene" title="Sodium naphthalene">sodium naphthalene</a> as an initiator.<a href="#cite_note-10">[10]</a><a href="#cite_note-ReferenceA-6">[6]</a><a href="#cite_note-11">[11]</a>

The naphthalene anion initiates polymerization by reducing styrene to its radical anion, which dimerizes to the dilithiodiphenylbutane, which then initiates the polymerization. These experiments relied on Szwarc's ability to control the levels of impurities which would destroy the highly reactive organometallic intermediates.

<div class="mw-heading mw-heading4"><h4 id="Living_α-olefin_polymerization">Living α-olefin polymerization</h4></div>

<a href="Alpha-olefins" class="mw-redirect" title="Alpha-olefins">α-olefins</a> can be polymerized through an anionic coordination polymerization in which the metal center of the catalyst is considered the counter cation for the <a href="Anionic" class="mw-redirect" title="Anionic">anionic</a> end of the alkyl chain (through a M-R coordination). Ziegler-Natta initiators were developed in the mid-1950s and are heterogeneous initiators used in the polymerization of alpha-olefins. Not only were these initiators the first to achieve relatively high molecular weight poly(1-alkenes) (currently the most widely produced thermoplastic in the world PE(<a href="Polyethylene" title="Polyethylene">Polyethylene</a>) and PP (<a href="Polypropylene" title="Polypropylene">Polypropylene</a>)<a href="#cite_note-b1-12">[12]</a> but the initiators were also capable of stereoselective polymerizations which is attributed to the <a href="Chirality_(chemistry)" title="Chirality (chemistry)">chiral</a> <a href="Crystal_structure" title="Crystal structure">Crystal structure</a> of the heterogeneous initiator.<a href="#cite_note-Principles-5">[5]</a> Due to the importance of this discovery Ziegler and Natta were presented with the <a rel="nofollow" class="external text" href="https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1963/">1963 Nobel Prize in chemistry</a>. Although the active species formed from the Ziegler-Natta initiator generally have long lifetimes (on the scale of hours or longer) the lifetimes of the propagating chains are shortened due to several chain transfer pathways (<a href="Beta-Hydride_elimination" class="mw-redirect" title="Beta-Hydride elimination">Beta-Hydride elimination</a> and transfer to the co-initiator) and as a result are not considered living.<a href="#cite_note-Principles-5">[5]</a>

Metallocene initiators are considered as a type of Ziegler-Natta initiators due to the use of the two-component system consisting of a <a href="Transition_metal" title="Transition metal">transition metal</a> and a group I-III metal co-initiator (for example <a href="Methylalumoxane" class="mw-redirect" title="Methylalumoxane">methylalumoxane</a> (MAO) or other alkyl aluminum compounds). The <a href="Metallocene" title="Metallocene">metallocene</a> initiators form homogeneous single site <a href="Catalyst" class="mw-redirect" title="Catalyst">catalysts</a> that were initially developed to study the impact that the catalyst structure had on the resulting polymers structure/properties; which was difficult for multi-site heterogeneous Ziegler-Natta initiators.<a href="#cite_note-b1-12">[12]</a> Owing to the discrete single site on the metallocene catalyst researchers were able to tune and relate how the ancillary ligand (those not directly involved in the chemical transformations) structure and the symmetry about the chiral metal center affect the microstructure of the polymer.<a href="#cite_note-13">[13]</a> However, due to chain breaking reactions (mainly Beta-Hydride elimination) very few metallocene based polymerizations are known.<a href="#cite_note-Principles-5">[5]</a>

By tuning the steric bulk and electronic properties of the ancillary ligands and their <a href="Substituent" title="Substituent">substituents</a> a class of initiators known as <a href="Chelation" title="Chelation">chelate</a> initiators (or post-metallocene initiators) have been successfully used for <a href="Stereospecificity" title="Stereospecificity">stereospecific</a> living polymerizations of alpha-olefins. The chelate initiators have a high potential for living polymerizations because the ancillary ligands can be designed to discourage or inhibit chain termination pathways. Chelate initiators can be further broken down based on the ancillary ligands; ansa-cyclopentyadienyl-amido initiators, alpha-diimine chelates and phenoxy-imine chelates.<a href="#cite_note-Principles-5">[5]</a>

<ul><li>Ansa-cyclopentadienyl-amido (CpA) initiators</li></ul>

CpA initiators have one <a href="Cyclopentadienyl" title="Cyclopentadienyl">cyclopentadienyl</a> substituent and one or more nitrogen substituents coordinated to the metal center (generally a Zr or Ti) (Odian). The dimethyl(pentamethylcyclopentyl)zirconium acetamidinate in figure___ has been used for a stereospecific living polymerization of 1-hexene at −10 °C. The resulting poly(1-hexene) was <a href="Tacticity#Isotactic_polymers" title="Tacticity">isotactic</a> (stereochemistry is the same between adjacent repeat units) confirmed by 13C-NMR. The multiple trials demonstrated a controllable and predictable (from catalyst to <a href="Monomer" title="Monomer">monomer</a> ratio) Mn with low Đ. The polymerization was further confirmed to be living by sequentially adding 2 portions of the monomer, the second portion was added after the first portion was already polymerized, and monitoring the Đ and Mn of the chain. The resulting polymer chains complied with the predicted Mn (with the total monomer concentration = portion 1 +2) and showed low Đ<a href="#cite_note-Ansa_chelates-14">[14]</a> suggesting the chains were still active, or living, as the second portion of monomer was added (5).

<ul><li>α-diimine chelate initiators</li></ul>

α-diimine chelate initiators are characterized by having a <a href="Diimine" title="Diimine">diimine</a> chelating ancillary ligand structure and which is generally coordinated to a late transition (i.e. Ni and Pd) metal center.

Brookhart et al. did extensive work with this class of catalysts and reported living polymerization for α-olefins<a href="#cite_note-Maurice_Brookhart-15">[15]</a> and demonstrated living α-olefin carbon monoxide alternating copolymers.<a href="#cite_note-MAurice_B_2-16">[16]</a>

<div class="mw-heading mw-heading3"><h3 id="Living_cationic_polymerization">Living cationic polymerization</h3></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Living_cationic_polymerization" title="Living cationic polymerization">Living cationic polymerization</a></div>

Monomers for living cationic polymerization are electron-rich alkenes such as vinyl ethers, <a href="Isobutylene" title="Isobutylene">isobutylene</a>, <a href="Styrene" title="Styrene">styrene</a>, and N-vinylcarbazole. The initiators are binary systems consisting of an electrophile and a Lewis acid. The method was developed around 1980 with contributions from Higashimura, Sawamoto and Kennedy. Typically, generating a stable carbocation for a prolonged period of time is difficult, due to the possibility for the cation to be quenched by a β-protons attached to another monomer in the backbone, or in a free monomer. Therefore, a different approach is taken<a href="#cite_note-Cowie-4">[4]</a><a href="#cite_note-Principles-5">[5]</a><a href="#cite_note-Goethals-17">[17]</a>

In this example, the carbocation is generated by the addition of a Lewis acid (co-initiator, along with the halogen "X" already on the polymer – see figure), which ultimately generates the carbocation in a weak equilibrium. This equilibrium heavily favors the dormant state, thus leaving little time for permanent quenching or termination by other pathways. In addition, a weak nucleophile (Nu:) can also be added to reduce the concentration of active species even further, thus keeping the polymer "living".<a href="#cite_note-Cowie-4">[4]</a><a href="#cite_note-Principles-5">[5]</a><a href="#cite_note-Goethals-17">[17]</a> However, it is important to note that by definition, the polymers described in this example are not technically living due to the introduction of a dormant state, as termination has only been decreased, not eliminated (though this topic is still up for debate). But, they do operate similarly, and are used in similar applications to those of true living polymerizations.

<div class="mw-heading mw-heading3"><h3 id="Living_ring-opening_metathesis_polymerization">Living ring-opening metathesis polymerization</h3></div>

Given the right reaction conditions <a href="Ring-opening_metathesis_polymerization" title="Ring-opening metathesis polymerization">ring-opening metathesis polymerization</a> (ROMP) can be rendered living. The first such systems were described by <a href="Robert_H._Grubbs" title="Robert H. Grubbs">Robert H. Grubbs</a> in 1986 based on <a href="Norbornene" title="Norbornene">norbornene</a> and <a href="Tebbe's_reagent" title="Tebbe's reagent">Tebbe's reagent</a> and in 1978 Grubbs together with <a href="Richard_R._Schrock" title="Richard R. Schrock">Richard R. Schrock</a> describing living polymerization with a <a href="Tungsten" title="Tungsten">tungsten</a> carbene complex.<a href="#cite_note-18">[18]</a>

Generally, ROMP reactions involve the conversion of a cyclic olefin with significant ring-strain (>5 kcal/mol), such as cyclobutene, norbornene, cyclopentene, etc., to a polymer that also contains double bonds. The important thing to note about ring-opening metathesis polymerizations is that the double bond is usually maintained in the backbone, which can allow it to be considered "living" under the right conditions.<a href="#cite_note-Grubbs-19">[19]</a>

For a ROMP reaction to be considered "living", several guidelines must be met:<a href="#cite_note-Grubbs-19">[19]</a>

<ol><li>Fast and complete initiation of the monomer. This means that the rate at which an initiating agent activates the monomer for polymerization, must happen very quickly.</li>

<li>How many monomers make up each polymer (the degree of polymerization) must be related linearly to the amount of monomer you started with.</li>

<li>The <a href="Dispersity" title="Dispersity">dispersity</a> of the polymer must be < 1.5. In other words, the distribution of how long your polymer chains are in your reaction must be very low.</li></ol>

With these guidelines in mind, it allows you to create a polymer that is well controlled both in content (what monomer you use) and properties of the polymer (which can be largely attributed to polymer chain length). It is important to note that living ring-opening polymerizations can be anionic or cationic.

Because living polymers have had their termination ability removed, this means that once your monomer has been consumed, the addition of more monomer will result in the polymer chains continuing to grow until all of the additional monomer is consumed. This will continue until the metal catalyst at the end of the chain is intentionally removed by the addition of a quenching agent. As a result, it may potentially allow one to create a <a href="Block_copolymer" class="mw-redirect" title="Block copolymer">block</a> or <a href="Gradient_copolymers" class="mw-redirect" title="Gradient copolymers">gradient copolymer</a> fairly easily and accurately. This can lead to a high ability to tune the properties of the polymer to a desired application (electrical/ionic conduction, etc.)<a href="#cite_note-Principles-5">[5]</a><a href="#cite_note-Grubbs-19">[19]</a>

<div class="mw-heading mw-heading3"><h3 id=""Living"_free_radical_polymerization">"Living" free radical polymerization</h3></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Reversible-deactivation_radical_polymerization" title="Reversible-deactivation radical polymerization">Reversible-deactivation radical polymerization</a></div>

Starting in the 1970s several new methods were discovered which allowed the development of living polymerization using <a href="Radical_(chemistry)" title="Radical (chemistry)">free radical</a> chemistry. These techniques involved <a href="Catalytic_chain_transfer" title="Catalytic chain transfer">catalytic chain transfer</a> polymerization, iniferter mediated polymerization, stable free radical mediated polymerization (SFRP), <a href="Atom_transfer_radical_polymerization" title="Atom transfer radical polymerization">atom transfer radical polymerization</a> (ATRP), <a href="Reversible_addition-fragmentation_chain_transfer" class="mw-redirect" title="Reversible addition-fragmentation chain transfer">reversible addition-fragmentation chain transfer</a> (<a href="RAFT_(chemistry)" class="mw-redirect" title="RAFT (chemistry)">RAFT</a>) polymerization, and iodine-transfer polymerization.

In "living" radical polymerization (or controlled radical polymerization (CRP)) the chain breaking pathways are severely depressed when compared to conventional radical polymerization (RP) and CRP can display characteristics of a living polymerization. However, since chain termination is not absent, but only minimized, CRP technically does not meet the requirements imposed by IUPAC for a living polymerization (see introduction for IUPAC definition). This issue has been up for debate the view points of different researchers can be found in a special issue of the Journal of Polymer Science titled <a rel="nofollow" class="external text" href="http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1099-0518(20000515)38:10%3C%3E1.0.CO;2-C/issuetoc">Living or Controlled ?</a>. The issue has not yet been resolved in the literature so it is often denoted as a "living" polymerization, quasi-living polymerization, pseudo-living and other terms to denote this issue.

There are two general strategies employed in CRP to suppress chain breaking reactions and promote fast initiation relative to propagation. Both strategies are based on developing a dynamic equilibrium amongst an active propagating radical and a dormant species.<a href="#cite_note-Braunecker_CRP-20">[20]</a>

The first strategy involves a reversible trapping mechanism in which the propagating radical undergoes an activation/deactivation (i.e. <a href="Atom-transfer_radical-polymerization" class="mw-redirect" title="Atom-transfer radical-polymerization">Atom-transfer radical-polymerization</a>) process with a species X. 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 (kp) and irreversibly terminate (kt) with another P*. X is normally a nitroxide (i.e. <a href="TEMPO" title="TEMPO">TEMPO</a> used in <a href="Nitroxide_Mediated_Radical_Polymerization" class="mw-redirect" title="Nitroxide Mediated Radical Polymerization">Nitroxide Mediated Radical Polymerization</a>) or an organometallic species. The dormant species (Pn-X) can be activated to regenerate the active propagating species (P*) spontaneously, thermally, using a catalyst and optically.<a href="#cite_note-Braunecker_CRP-20">[20]</a><a href="#cite_note-Matyjaszewski-21">[21]</a>

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. <a href="Reversible_addition%E2%88%92fragmentation_chain-transfer_polymerization" title="Reversible addition−fragmentation chain-transfer polymerization">Reversible addition−fragmentation chain-transfer polymerization</a>). The DT based CRP's follow the conventional kinetics of radical polymerization, that is slow initiation and fast termination, but the transfer agent (Pm-X or Pn-X) is present in a much higher concentration compared to the radical initiator. The propagating radical species undergoes a thermally neutral exchange with the dormant transfer agent through atom transfer, group transfer or addition fragment chemistry.<a href="#cite_note-Braunecker_CRP-20">[20]</a>

<div class="mw-heading mw-heading3"><h3 id="Living_chain-growth_polycondensations">Living chain-growth polycondensations</h3></div>

Chain growth polycondensation polymerizations were initially developed under the premise that a change in substituent effects of the polymer, relative to the monomer, causes the polymers end group to be more reactive this has been referred to as "reactive intermediate polycondensation". The essential result is monomers preferentially react with the activated polymer end groups over reactions with other monomers. This preferred reactivity is the fundamental difference when categorizing a polymerization mechanism as chain-growth as opposed to <a href="Step-growth_polymerization" title="Step-growth polymerization">step-growth</a> in which the monomer and polymer chain end group have equal reactivity (the reactivity is uncontrolled). Several strategies were employed to minimize monomer-monomer reactions (or self-condensation) and polymerizations with low D and controllable Mn have been attained by this mechanism for small molecular weight polymers.<a href="#cite_note-Yokozawa_1-22">[22]</a> However, for high molecular weight polymer chains (i.e. small initiator to monomer ratio) the Mn is not easily to controlled, for some monomers, since self-condensation between monomers occurred more frequently due to the low propagating species concentration.<a href="#cite_note-Yokozawa_1-22">[22]</a>

<div class="mw-heading mw-heading4"><h4 id="Catalyst-transfer_polycondensation">Catalyst-transfer polycondensation</h4></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Living_chain-growth_polycondensation" class="mw-redirect" title="Living chain-growth polycondensation">Living chain-growth polycondensation</a></div>

<a href="Catalyst_transfer_polycondensation" class="mw-redirect" title="Catalyst transfer polycondensation">Catalyst transfer polycondensation</a> (CTP) is a chain-growth polycondensation mechanism in which the monomers do not directly react with one another and instead the monomer will only react with the polymer end group through a catalyst-mediated mechanism.<a href="#cite_note-Yokozawa_1-22">[22]</a> The general process consists of the catalyst activating the polymer end group followed by a reaction of the end group with a 2nd incoming monomer. The catalyst is then transferred to the elongated chain while activating the end group (as shown below).<a href="#cite_note-Yokozawa_2-23">[23]</a>

Catalyst transfer polycondensation allows for the living polymerization of π-conjugated polymers and was discovered by Tsutomu Yokozawa in 2004<a href="#cite_note-Yokozawa_2-23">[23]</a> and Richard McCullough.<a href="#cite_note-24">[24]</a> In CTP the propagation step is based on organic cross coupling reactions (i.e. <a href="Kumada_coupling" title="Kumada coupling">Kumada coupling</a>, <a href="Sonogashira_coupling" title="Sonogashira coupling">Sonogashira coupling</a>, <a rel="nofollow" class="external text" href="https://www.organic-chemistry.org/namedreactions/negishi-coupling.shtm">Negishi coupling</a>) top form carbon carbon bonds between difunctional monomers. When Yokozawa and McCullough independently discovered the polymerization using a metal catalyst to couple a <a href="Grignard_Reaction" class="mw-redirect" title="Grignard Reaction">Grignard reagent</a> with an organohalide making a new carbon-carbon bond. The mechanism below shows the formation of poly(3-alkylthiophene) using a Ni initiator (Ln can be <a href="1%2C3-Bis(diphenylphosphino)propane" title="1,3-Bis(diphenylphosphino)propane"> 1,3-Bis(diphenylphosphino)propane (dppp)</a>) and is similar to the conventional mechanism for <a href="Kumada_coupling" title="Kumada coupling">Kumada coupling</a> involving an <a href="Oxidative_addition" title="Oxidative addition">oxidative addition</a>, a <a href="Transmetalation" title="Transmetalation">transmetalation</a> and a <a href="Reductive_elimination" title="Reductive elimination">reductive elimination</a> step. However, there is a key difference, following reductive elimination in CTP, an associative complex is formed (which has been supported by intra-/intermolecular oxidative addition competition experiments<a href="#cite_note-McNeil_1-8">[8]</a>) and the subsequent oxidative addition occurs between the metal center and the associated chain (an intramolecular pathway). Whereas in a coupling reaction the newly formed alkyl/aryl compound diffuses away and the subsequent oxidative addition occurs between an incoming Ar–Br bond and the metal center.

The associative complex is essential to for polymerization to occur in a living fashion since it allows the metal to undergo a preferred intramolecular oxidative addition and remain with a single propagating chain (consistent with chain-growth mechanism), as opposed to an intermolecular oxidative addition with other monomers present in the solution (consistent with a step-growth, non-living, mechanism).<a href="#cite_note-Kiriy-25">[25]</a><a href="#cite_note-Bryan_8395–8405-26">[26]</a> The monomer scope of CTP has been increasing since its discovery and has included poly(phenylene)s, poly(fluorine)s, poly(selenophene)s and poly(pyrrole)s.<a href="#cite_note-Kiriy-25">[25]</a><a href="#cite_note-Bryan_8395–8405-26">[26]</a>

<div class="mw-heading mw-heading3"><h3 id="Living_group-transfer_polymerization">Living group-transfer polymerization</h3></div>

Group-transfer polymerization also has characteristics of living polymerization.<a href="#cite_note-27">[27]</a> It is applied to alkylated <a href="Methacrylate" title="Methacrylate">methacrylate</a> monomers and the initiator is a <a href="Silyl_ketene_acetal" class="mw-redirect" title="Silyl ketene acetal">silyl ketene acetal</a>. New monomer adds to the initiator and to the active growing chain in a <a href="Michael_reaction" class="mw-redirect" title="Michael reaction">Michael reaction</a>. With each addition of a monomer group the trimethylsilyl group is transferred to the end of the chain. The active <a href="Chain-end" class="mw-redirect" title="Chain-end">chain-end</a> is not ionic as in anionic or cationic polymerization but is covalent. The reaction can be catalysed by bifluorides and bioxyanions such as tris(dialkylamino)sulfonium bifluoride or tetrabutyl ammonium bibenzoate. The method was discovered in 1983 by <a href="Owen_Webster" title="Owen Webster">Owen Webster</a><a href="#cite_note-28">[28]</a> and the name first suggested by <a href="Barry_Trost" title="Barry Trost">Barry Trost</a>.

<div class="mw-heading mw-heading2"><h2 id="Applications">Applications</h2></div>

Living polymerizations are used in the commercial synthesis of many polymers.

<div class="mw-heading mw-heading3"><h3 id="Copolymer_synthesis_and_applications">Copolymer synthesis and applications</h3></div>

<a href="Copolymer" title="Copolymer">Copolymers</a> are polymers consisting of multiple different monomer species, and can be arranged in various orders, three of which are seen in the figure below.

While there exist others (alternating copolymers, graft copolymers, and stereoblock copolymers), these three are more common in the scientific literature.<a href="#cite_note-Cowie-4">[4]</a> In addition, block copolymers can exist as many types, including triblock (A-B-A), alternating block (A-B-A-B-A-B), etc.

Of these three types, block and gradient copolymers are commonly synthesized through living polymerizations, due to the ease of control living polymerization provides. Copolymers are highly desired due to the increased flexibility of properties a polymer can have compared to their homopolymer counterparts. The synthetic techniques used range from ROMP to generic anionic or cationic living polymerizations.<a href="#cite_note-Cowie-4">[4]</a><a href="#cite_note-Principles-5">[5]</a>

Copolymers, due to their unique tunability of properties, can have a wide range of applications. One example (of many) is nano-scale <a rel="nofollow" class="external text" href="https://www.nist.gov/mml/msed/electronics_materials/templatedassembly.cfm">lithography</a> using block copolymers. One used frequently is a block copolymer made of polystyrene and poly(methyl methacrylate) (abbreviated PS-b-PMMA). This copolymer, upon proper thermal and processing conditions, can form cylinders on the order of a few tens of nanometers in diameter of PMMA, surrounded by a PS matrix. These cylinders can then be etched away under high exposure to UV light and acetic acid, leaving a porous PS matrix.<a href="#cite_note-In_7855–7860-29">[29]</a><a href="#cite_note-30">[30]</a><a href="#cite_note-31">[31]</a>

The unique property of this material is that the size of the pores (or the size of the PMMA cylinders) can be easily tuned by the ratio of PS to PMMA in the synthesis of the copolymer. This can be easily tuned due to the easy control given by living polymerization reactions, thus making this technique highly desired for various nanoscale patterning of different materials for applications to catalysis, electronics, etc.

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}

/* end https://en.wikipedia.org/ */

</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;">

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite id="CITEREFHalasa1981" class="citation journal cs1">Halasa, A. F. (1981). "Recent Advances in Anionic Polymerization". Rubber Chemistry and Technology. 54 (3): 627–640. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.5254%2F1.3535823">10.5254/1.3535823</a>.</cite>

</li>

<li id="cite_note-2"><a href="#cite_ref-2">^</a> Moad, Graeme and Solomon, David H. (2006) The Chemistry of Radical Polymerization. 2nd ed. Elsevier. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-08-044286-2</bdi>

</li>

<li id="cite_note-3"><a href="#cite_ref-3">^</a> <cite id="CITEREFJenkinsKratochvílSteptoSuter1996" class="citation journal cs1">Jenkins, A. D.; Kratochvíl, P.; Stepto, R. F. T.; Suter, U. W. (1996). <a rel="nofollow" class="external text" href="http://pac.iupac.org/publications/pac/pdf/1996/pdf/6812x2287.html">"Glossary of basic terms in polymer science (IUPAC Recommendations 1996)"</a>. <a href="Pure_and_Applied_Chemistry" title="Pure and Applied Chemistry">Pure and Applied Chemistry</a>. 68 (12): 2287–2311. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1351%2Fpac199668122287">10.1351/pac199668122287</a>.</cite>

</li>

<li id="cite_note-Cowie-4">^ <a href="#cite_ref-Cowie_4-0">a</a> <a href="#cite_ref-Cowie_4-1">b</a> <a href="#cite_ref-Cowie_4-2">c</a> <a href="#cite_ref-Cowie_4-3">d</a> <a href="#cite_ref-Cowie_4-4">e</a> <a href="#cite_ref-Cowie_4-5">f</a> <cite id="CITEREFCowie2007" class="citation book cs1">Cowie, J.M.G. (2007). Polymers chemistry and physics of modern materials (3rd ed / J.M.G. Cowie and Valeria Arrighi ed.). Boca Raton: Taylor & Francis. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9780849398131</bdi>.</cite>

</li>

<li id="cite_note-Principles-5">^ <a href="#cite_ref-Principles_5-0">a</a> <a href="#cite_ref-Principles_5-1">b</a> <a href="#cite_ref-Principles_5-2">c</a> <a href="#cite_ref-Principles_5-3">d</a> <a href="#cite_ref-Principles_5-4">e</a> <a href="#cite_ref-Principles_5-5">f</a> <a href="#cite_ref-Principles_5-6">g</a> <a href="#cite_ref-Principles_5-7">h</a> <a href="#cite_ref-Principles_5-8">i</a> <a href="#cite_ref-Principles_5-9">j</a> <a href="#cite_ref-Principles_5-10">k</a> <a href="#cite_ref-Principles_5-11">l</a> <cite id="CITEREFOdian2004" class="citation book cs1">Odian, George (2004). Principles of polymerization (4. ed.). Hoboken, NJ: Wiley-Interscience. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0471274001</bdi>.</cite>

</li>

<li id="cite_note-ReferenceA-6">^ <a href="#cite_ref-ReferenceA_6-0">a</a> <a href="#cite_ref-ReferenceA_6-1">b</a> <cite id="CITEREFSzwarcLevyMilkovich1956" class="citation journal cs1">Szwarc, M.; Levy, M.; Milkovich, R. (1956). "Polymerization Initiated by Electron Transfer to Monomer. A New Method of Formation of Block Polymers1". Journal of the American Chemical Society. 78 (11): 2656–2657. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja01592a101">10.1021/ja01592a101</a>.</cite>

</li>

<li id="cite_note-7"><a href="#cite_ref-7">^</a> <cite id="CITEREFM._Szwarc1956" class="citation journal cs1">M. Szwarc (1956). ""Living" polymers". Nature. 178 (4543): 1168. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1038%2F1781168a0">10.1038/1781168a0</a>.</cite>

</li>

<li id="cite_note-McNeil_1-8">^ <a href="#cite_ref-McNeil_1_8-0">a</a> <a href="#cite_ref-McNeil_1_8-1">b</a> <cite id="CITEREFMcNeil2013" class="citation journal cs1">McNeil, Anne; Bryan, Zachary (2013). "Evidence for a preferential intramolecular oxidative addition in Ni-catalyzed cross-coupling reactions and their impact on chain-growth polymerizations". Chem. Sci. 4 (4): 1620–1624. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1039%2FC3SC00090G">10.1039/C3SC00090G</a>.</cite><code class="cs1-code">{{cite journal}}</code>: CS1 maint: multiple names: authors list (link)

</li>

<li id="cite_note-9"><a href="#cite_ref-9">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://goldbook.iupac.org/LT07156.html">"Living polymer"</a>. Gold Book. <a href="International_Union_of_Pure_and_Applied_Chemistry" title="International Union of Pure and Applied Chemistry">International Union of Pure and Applied Chemistry </a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1351%2Fgoldbook.LT07156">10.1351/goldbook.LT07156</a>. Retrieved 4 January 2023.</cite>

</li>

<li id="cite_note-10"><a href="#cite_ref-10">^</a> <cite id="CITEREFSzwarc1956" class="citation journal cs1">Szwarc, M. (1956). "'Living' Polymers". Nature. 178 (4543): 1168–1169. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1956Natur.178.1168S">1956Natur.178.1168S</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1038%2F1781168a0">10.1038/1781168a0</a>.</cite>

</li>

<li id="cite_note-11"><a href="#cite_ref-11">^</a> Tatemoto, Masayoshi and Nakagawa, Tsuneo "Segmented polymers containing fluorine and iodine and their production" <a rel="nofollow" class="external text" href="https://patents.google.com/patent/US4158678">U.S. patent 4,158,678</a>. Priority date 30 June 1976.

</li>

<li id="cite_note-b1-12">^ <a href="#cite_ref-b1_12-0">a</a> <a href="#cite_ref-b1_12-1">b</a> <cite id="CITEREFCraverCarraher,_C.2000" class="citation book cs1">Craver, C.; Carraher, C. (2000). Applied Polymer Science: 21st Century. Elsevier. pp. 1022–1023.</cite>

</li>

<li id="cite_note-13"><a href="#cite_ref-13">^</a> <cite id="CITEREFCoates2000" class="citation journal cs1">Coates, Geoffrey W. (April 2000). "Precise Control of Polyolefin Stereochemistry Using Single-Site Metal Catalysts". Chemical Reviews. 100 (4): 1223–1252. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fcr990286u">10.1021/cr990286u</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/11749265">11749265</a>.</cite>

</li>

<li id="cite_note-Ansa_chelates-14"><a href="#cite_ref-Ansa_chelates_14-0">^</a> <cite id="CITEREFJayaratneSita2000" class="citation journal cs1">Jayaratne, K.; Sita, L (2000). "Stereospecific Living Ziegler−Natta Polymerization of 1-Hexene". J. Am. Chem. Soc. 122 (5): 958–959. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja993808w">10.1021/ja993808w</a>.</cite>

</li>

<li id="cite_note-Maurice_Brookhart-15"><a href="#cite_ref-Maurice_Brookhart_15-0">^</a> <cite id="CITEREFKillianTempelJohnsonBrookhart1996" class="citation journal cs1">Killian, C. M.; Tempel, D. J.; Johnson, L. K.; Brookhart, M. (1996). "Living Polymerization of α-Olefins Using NiII−α-Diimine Catalysts. Synthesis of New Block Polymers Based on α-Olefins". Journal of the American Chemical Society. 118 (46): 11664–11665. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja962516h">10.1021/ja962516h</a>.</cite>

</li>

<li id="cite_note-MAurice_B_2-16"><a href="#cite_ref-MAurice_B_2_16-0">^</a> <cite id="CITEREFBrookhartRixDesimoneBarborak1992" class="citation journal cs1">Brookhart, M.; Rix, F. C.; Desimone, J. M.; Barborak, J. C. (1992). "Palladium(II) catalysts for living alternating copolymerization of olefins and carbon monoxide". Journal of the American Chemical Society. 114 (14): 5894–5895. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja00040a082">10.1021/ja00040a082</a>.</cite>

</li>

<li id="cite_note-Goethals-17">^ <a href="#cite_ref-Goethals_17-0">a</a> <a href="#cite_ref-Goethals_17-1">b</a> <cite id="CITEREFGoethalsDuprez,_F2007" class="citation journal cs1">Goethals, E; Duprez, F (2007). "Carbocationic polymerizations". Progress in Polymer Science. 32 (2): 220–246. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.progpolymsci.2007.01.001">10.1016/j.progpolymsci.2007.01.001</a>.</cite>

</li>

<li id="cite_note-18"><a href="#cite_ref-18">^</a> <cite id="CITEREFSchrockFeldmanCannizzoGrubbs1987" class="citation journal cs1">Schrock, R. R.; Feldman, J.; Cannizzo, L. F.; Grubbs, R. H. (1987). "Ring-opening polymerization of norbornene by a living tungsten alkylidene complex". <a href="Macromolecules_(journal)" title="Macromolecules (journal)">Macromolecules</a>. 20 (5): 1169–1172. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1987MaMol..20.1169S">1987MaMol..20.1169S</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fma00171a053">10.1021/ma00171a053</a>.</cite>

</li>

<li id="cite_note-Grubbs-19">^ <a href="#cite_ref-Grubbs_19-0">a</a> <a href="#cite_ref-Grubbs_19-1">b</a> <a href="#cite_ref-Grubbs_19-2">c</a> <cite id="CITEREFBielawskiGrubbs,_Robert_H.2007" class="citation journal cs1"><a href="Christopher_Bielawski" title="Christopher Bielawski">Bielawski, Christopher W.</a>; Grubbs, Robert H. (2007). "Living ring-opening metathesis polymerization". Progress in Polymer Science. 32 (1): 1–29. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.progpolymsci.2006.08.006">10.1016/j.progpolymsci.2006.08.006</a>.</cite>

</li>

<li id="cite_note-Braunecker_CRP-20">^ <a href="#cite_ref-Braunecker_CRP_20-0">a</a> <a href="#cite_ref-Braunecker_CRP_20-1">b</a> <a href="#cite_ref-Braunecker_CRP_20-2">c</a> <cite id="CITEREFBrauneckerMatyjaszewski,_Krzysztof2007" class="citation journal cs1">Braunecker, Wade A.; Matyjaszewski, Krzysztof (2007). "Controlled/living radical polymerization: Features, developments, and perspectives". Progress in Polymer Science. 32 (1): 93–146. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.progpolymsci.2006.11.002">10.1016/j.progpolymsci.2006.11.002</a>.</cite>

</li>

<li id="cite_note-Matyjaszewski-21"><a href="#cite_ref-Matyjaszewski_21-0">^</a> <cite id="CITEREFMatyjaszewski" class="citation web cs1">Matyjaszewski. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140314175012/http://www.cmu.edu/maty/crp/feature-development-crp/features.html#feature%202">"Features of Controlled "Living" Polymerization"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.cmu.edu/maty/crp/feature-development-crp/features.html#feature%202">the original</a> on 14 March 2014.</cite>

</li>

<li id="cite_note-Yokozawa_1-22">^ <a href="#cite_ref-Yokozawa_1_22-0">a</a> <a href="#cite_ref-Yokozawa_1_22-1">b</a> <a href="#cite_ref-Yokozawa_1_22-2">c</a> <cite id="CITEREFYokozawaYokoyama2007" class="citation journal cs1">Yokozawa, T.; Yokoyama, A. (2007). "Chain-growth polycondensation: The living polymerization process in polycondensation". Progress in Polymer Science. 32: 147–172. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.progpolymsci.2006.08.001">10.1016/j.progpolymsci.2006.08.001</a>.</cite>

</li>

<li id="cite_note-Yokozawa_2-23">^ <a href="#cite_ref-Yokozawa_2_23-0">a</a> <a href="#cite_ref-Yokozawa_2_23-1">b</a> <cite id="CITEREFMiyakoshiYokoyama,_AkihiroYokozawa,_Tsutomu2005" class="citation journal cs1">Miyakoshi, Ryo; Yokoyama, Akihiro; Yokozawa, Tsutomu (2005). <a rel="nofollow" class="external text" href="https://figshare.com/articles/Catalyst_Transfer_Polycondensation_Mechanism_of_Ni_Catalyzed_Chain_Growth_Polymerization_Leading_to_Well_Defined_Poly_3_hexylthiophene_/3251725">"Catalyst-Transfer Polycondensation. Mechanism of Ni-Catalyzed Chain-Growth Polymerization Leading to Well-Defined Poly(3-hexylthiophene)"</a>. Journal of the American Chemical Society. 127 (49): 17542–17547. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja0556880">10.1021/ja0556880</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/16332106">16332106</a>.</cite>

</li>

<li id="cite_note-24"><a href="#cite_ref-24">^</a> <cite id="CITEREFIovuSheina,_Elena_E.Gil,_Roberto_R.McCullough,_Richard_D.2005" class="citation journal cs1">Iovu, Mihaela Corina; Sheina, Elena E.; Gil, Roberto R.; McCullough, Richard D. (October 2005). "Experimental Evidence for the Quasi-"Living" Nature of the Grignard Metathesis Method for the Synthesis of Regioregular Poly(3-alkylthiophenes)". Macromolecules. 38 (21): 8649–8656. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2005MaMol..38.8649I">2005MaMol..38.8649I</a>. <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.206.3875">10.1.1.206.3875</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fma051122k">10.1021/ma051122k</a>.</cite>

</li>

<li id="cite_note-Kiriy-25">^ <a href="#cite_ref-Kiriy_25-0">a</a> <a href="#cite_ref-Kiriy_25-1">b</a> <cite id="CITEREFKiriySenkovskyy,_VolodymyrSommer,_Michael2011" class="citation journal cs1">Kiriy, Anton; Senkovskyy, Volodymyr; Sommer, Michael (4 October 2011). "Kumada Catalyst-Transfer Polycondensation: Mechanism, Opportunities, and Challenges". Macromolecular Rapid Communications. 32 (19): 1503–1517. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fmarc.201100316">10.1002/marc.201100316</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/21800394">21800394</a>.</cite>

</li>

<li id="cite_note-Bryan_8395–8405-26">^ <a href="#cite_ref-Bryan_8395–8405_26-0">a</a> <a href="#cite_ref-Bryan_8395–8405_26-1">b</a> <cite id="CITEREFBryanMcNeil,_Anne_J.2013" class="citation journal cs1">Bryan, Zachary J.; McNeil, Anne J. (12 November 2013). "Conjugated Polymer Synthesis via Catalyst-Transfer Polycondensation (CTP): Mechanism, Scope, and Applications". Macromolecules. 46 (21): 8395–8405. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2013MaMol..46.8395B">2013MaMol..46.8395B</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fma401314x">10.1021/ma401314x</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:101567648">101567648</a>.</cite>

</li>

<li id="cite_note-27"><a href="#cite_ref-27">^</a> Davis, Fred J. (2004) Polymer chemistry: a practical approach. Oxford University Press. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-19-850309-5</bdi> .

</li>

<li id="cite_note-28"><a href="#cite_ref-28">^</a> <cite id="CITEREFWebsterHertlerSogahFarnham1983" class="citation journal cs1">Webster, O. W.; Hertler, W. R.; Sogah, D. Y.; Farnham, W. B.; RajanBabu, T. V. (1983). "Group-transfer polymerization. 1. A new concept for addition polymerization with organosilicon initiators". <a href="J._Am._Chem._Soc." class="mw-redirect" title="J. Am. Chem. Soc.">J. Am. Chem. Soc.</a> 105 (17): 5706–5708. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja00355a039">10.1021/ja00355a039</a>.</cite>

</li>

<li id="cite_note-In_7855–7860-29"><a href="#cite_ref-In_7855–7860_29-0">^</a> <cite id="CITEREFInLa,_Young-HyePark,_Sang-MinNealey,_Paul_F.2006" class="citation journal cs1">In, Insik; La, Young-Hye; Park, Sang-Min; <a href="Paul_Nealey" title="Paul Nealey">Nealey, Paul F.</a>; Gopalan, Padma (August 2006). "Side-Chain-Grafted Random Copolymer Brushes as Neutral Surfaces for Controlling the Orientation of Block Copolymer Microdomains in Thin Films". Langmuir. 22 (18): 7855–7860. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fla060748g">10.1021/la060748g</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/16922574">16922574</a>.</cite>

</li>

<li id="cite_note-30"><a href="#cite_ref-30">^</a> <cite id="CITEREFLiuGong,_YanchunHe,_LongbinXie,_Bo2010" class="citation journal cs1">Liu, Yuanjun; Gong, Yanchun; He, Longbin; Xie, Bo; Chen, Xi; Han, Min; Wang, Guanghou (2010). "Formation of periodic nanoring arrays on self-assembled PS-b-PMMA film under rapid solvent-annealing". Nanoscale. 2 (10): 2065–8. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2010Nanos...2.2065L">2010Nanos...2.2065L</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1039%2Fc0nr00207k">10.1039/c0nr00207k</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/20820641">20820641</a>.</cite>

</li>

<li id="cite_note-31"><a href="#cite_ref-31">^</a> <cite id="CITEREFEdwardsMontague,_M._F.Solak,_H._H.Hawker,_C._J.2004" class="citation journal cs1">Edwards, E. W.; Montague, M. F.; Solak, H. H.; Hawker, C. J.; Nealey, P. F. (4 August 2004). "Precise Control over Molecular Dimensions of Block-Copolymer Domains Using the Interfacial Energy of Chemically Nanopatterned Substrates". Advanced Materials. 16 (15): 1315–1319. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fadma.200400763">10.1002/adma.200400763</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:95470388">95470388</a>.</cite>

</li>

</ol></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li>IUPAC <a href="Gold_Book" class="mw-redirect" title="Gold Book">Gold Book</a> <a rel="nofollow" class="external text" href="https://goldbook.iupac.org/terms/view/L03597">Definition</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20070929181711/http://organicdivision.org/essays_2002/keaton.pdf">Living Ziegler-Natta Polymerization Article</a></li>

<li><a rel="nofollow" class="external text" href="http://www.weizmann.ac.il/ICS/booklet/18/pdf/levy.pdf">Living polymers 50 years of evolution Article</a></li></ul></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-05-26" href="https://en.wikipedia.org/wiki/?title=Living_polymerization&oldid=1292277667">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

</div>

</div></div>

</div>

</main>

</div>

</body></html>