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In polymer chemistry, living polymerization is a form of chain growth polymerization where the ability of a growing polymer chain to terminate has been removed. This can be accomplished in a variety of ways. Chain termination and chain transfer reactions are absent and the rate of chain initiation is also much larger than the rate of chain propagation. The result is that the polymer chains grow at a more constant rate than seen in traditional chain polymerization and their lengths remain very similar (i.e. they have a very low polydispersity index). Living polymerization is a popular method for synthesizing block copolymers since the polymer can be synthesized in stages, each stage containing a different monomer. Additional advantages are predetermined molar mass and control over end-group

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  • Lebende Polymerisation (de)
  • Polymérisation vivante (fr)
  • Polimerizzazione vivente (it)
  • Living polymerization (en)
  • Levende polymerisatie (nl)
  • Polimeryzacja żyjąca (pl)
  • 活性聚合反應 (zh)
rdfs:comment
  • La polymérisation vivante est une polymérisation en chaîne où les centres actifs sont pérennes. Cela implique l'absence de réactions de transfert de chaîne ou de terminaison. Cette propriété particulière est notamment utilisée pour synthétiser des copolymères à blocs. (fr)
  • Unter einer lebenden Polymerisation versteht man Kettenpolymerisationen, bei denen keine Abbruchreaktionen und Kettenübertragungen auftreten. Unter „lebenden Bedingungen“ wird die Kontrolle von Molmassen mit enger Verteilung möglich. Des Weiteren lassen sich unter diesen Voraussetzungen klar definierte Polymerstrukturen, wie zum Beispiel Blockcopolymere mit bestimmten Sequenzlängen erzeugen. Der Nachteil dieser Reaktionsführung ist die hohe Sensitivität gegenüber Verunreinigungen. Aus diesem Grund sind Schutzgastechnik und absolut trockene, sowie reine Chemikalien fundamentale Voraussetzungen. Der Begriff living polymerisation wurde 1956 von Michael Szwarc für die anionische Polymerisation von Styrol in aprotischen Lösungsmitteln eingeführt. (de)
  • In polymer chemistry, living polymerization is a form of chain growth polymerization where the ability of a growing polymer chain to terminate has been removed. This can be accomplished in a variety of ways. Chain termination and chain transfer reactions are absent and the rate of chain initiation is also much larger than the rate of chain propagation. The result is that the polymer chains grow at a more constant rate than seen in traditional chain polymerization and their lengths remain very similar (i.e. they have a very low polydispersity index). Living polymerization is a popular method for synthesizing block copolymers since the polymer can be synthesized in stages, each stage containing a different monomer. Additional advantages are predetermined molar mass and control over end-group (en)
  • Nella chimica dei polimeri, una polimerizzazione vivente è un tipo di polimerizzazione a catena in cui non si ha fase di terminazione e la catena continua a propagarsi. Questo si può verificare in diversi modi. Condizioni necessarie affinché si parli di questo tipo di polimerizzazione: * Non si hanno né fase di terminazione * La reazione di inizio è velocissima, molto di più che quella di propagazione. La definizione ufficiale della IUPAC è: "una polimerizzazione a catena in cui il trasferimento di catena e la terminazione sono assenti". (it)
  • Polimeryzacja żyjąca – rodzaj polimeryzacji łańcuchowej, w której zostały wyeliminowane wszystkie reakcje terminacji (zakończania łańcucha polimerów) a szybkość reakcji inicjowania jest przynajmniej o jeden rząd większa od szybkości reakcji propagacji (wzrostu łańcuchów polimeru). Polimeryzacja żyjąca jest bardzo trudna technicznie do przeprowadzenia, ale ma szereg unikatowych zalet, dla których dąży się do jej osiągania, np.: (pl)
  • Levende polymerisatie is een bijzondere vorm van additiepolymerisatie, waarbij er geen ketenoverdracht of terminatiereactie plaatsvindt. In het ideale geval gebeuren de verschillende stappen - initiatie, propagatie en terminatie - achter elkaar. Na de initiatie zullen de polymeerketens gelijktijdig aangroeien met dezelfde snelheid, totdat alle monomeer is opgebruikt. Het gevolg is dat alle polymeerketens vrijwel even lang zijn, of anders gezegd: de polydispersiteit van het polymeer is bijna gelijk aan 1 (in het ideale geval zijn alle polymeerketens exact even lang en is de polydispersiteit gelijk aan 1, dit wil zeggen dat het polymeer monodispers is). (nl)
  • 活性聚合反應在高分子化學中是一種鏈增長聚合反應,然而在活性聚合反應中,聚合物鏈的活性端並不具有的能力。這種聚合反應中缺少反應和鏈轉移反應,且聚合起始的速度遠比鏈成長的速度來得大,以上特性產生的結果是:聚合物鏈生長的速度比傳統聚合方法的速度還來得恆定,且這些鏈的長度是相似的(即它們具有非常低的)。活性聚合反應對於區段共聚物的合成是一種常用的方法,由於可以分階段進行合成,所以可以控制不同階段合成的鏈段上具有不同的單體。另外的優點是可以預定想合成的聚合物的分子量,及控制末端基團。 IUPAC 定義活性聚合反應: 不具鏈轉移及鏈終止反應的鏈增長聚合反應注: 在許多情況下, 鏈的起始反應速度比鏈的延長速度來得快, 使動能鏈所帶的能量在聚合反應中是穩定的。 活性聚合反應是理想的聚合反應,因為它為聚合物的合成提供了精準度及可控性──由於聚合物的特性常常表現在他們的微觀結構以及分子量上,這兩點非常重要。相較之下,要在非活性聚合反應中,對分子量和的可控性是比較低的。 在許多情況下,活性聚合反應會被混淆或認為是控制聚合反應。雖然這兩個反應非常相似,但還是有明顯的區別來區分這兩個反應。活性聚合反應被定義為終止或鏈轉移被移除的聚合反應,可控制聚合反應終止的地方被抑制,但不被移除,藉此來引發聚合物的休眠狀態。然而,這區分仍然是一個有爭議的文獻。 主要的活性聚合反應技術是: (zh)
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