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Solvent Effects on ATRP of Oligo(ethylene glycol) Methacrylate. Exploring the Limits of Control
KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.ORCID-id: 0000-0003-0663-0751
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.ORCID-id: 0000-0002-8348-2273
2009 (engelsk)Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 42, nr 9, s. 3302-3308Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Five copper complexes in combination with six monomer-solvent mixtures have been used to investigate the solvent effects oil ATRP of oligo(ethylene glycol) methacrylate (OEGMA). The redox properties of the copper complexes in OEGMA-solvent mixtures and the apparent rate constants (k(p)(app)) for ATRP of OEGMA were correlated to the degree of control over the polymerizations. Based on this correlation, a general discussion of the limits of control in ATRIP is carried out. One of the key parameters for control in ATRP is the propagation rate constant, making the choice of monomer essential for the design of ail ATRP system. Also, the solvent effects oil the ATRP equilibrium constant (K-ATRP) affect the limit of control (i.e., the apparent rate constant above which control is lost). The choice of copper complex is also more important than the choice of solvent for the design of a well-controlled ATRP system.

sted, utgiver, år, opplag, sider
2009. Vol. 42, nr 9, s. 3302-3308
Emneord [en]
TRANSFER RADICAL POLYMERIZATION; PROPAGATION RATE COEFFICIENTS; ACTIVATION RATE CONSTANTS; METHYL-METHACRYLATE; AMBIENT-TEMPERATURE; AQUEOUS-MEDIA; COMPLEXES; STYRENE; COPPER; COUNTERION
Identifikatorer
URN: urn:nbn:se:kth:diva-18388DOI: 10.1021/ma8028425ISI: 000265781300012Scopus ID: 2-s2.0-66549102560OAI: oai:DiVA.org:kth-18388DiVA, id: diva2:336435
Merknad
QC 20100525Tilgjengelig fra: 2010-08-05 Laget: 2010-08-05 Sist oppdatert: 2017-12-12bibliografisk kontrollert
Inngår i avhandling
1. Understanding the mechanisms behind atom transfer radical polymerization: exploring the limit of control
Åpne denne publikasjonen i ny fane eller vindu >>Understanding the mechanisms behind atom transfer radical polymerization: exploring the limit of control
2011 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Atom transfer radical polymerization (ATRP) is one of the most commonly employed techniques for controlled radical polymerization. ATRP has great potential for the development of new materials due to the ability to control molecular weight and polymer architecture. To fully utilize the potential of ATRP as polymerization technique, the mechanism and the dynamics of the ATRP equilibrium must be well understood.

In this thesis, various aspects of the ATRP process are explored through both laboratory experiments and computer modeling. Solvent effects, the limit of control and the use of iron as the mediator have been investigated. It was shown for copper mediated ATRP that the redox properties of the mediator and the polymerization properties were significantly affected by the solvent. As expected, the apparent rate constant (kpapp) increased with increasing activity of the mediator, but an upper limit was reached, where after kpapp was practically independent of the mediator potential. The degree of control deteriorated as the limit was approached.

In the simulations, which were based on the thermodynamic properties of the ATRP equilibrium, the same trend of increasing kpapp with increasing mediator activity was seen and a maximum was also reached. The simulation results could be used to describe the limit of control. The maximum equilibrium constant for controlled ATRP was correlated to the propagation rate constant, which enables the design of controlled ATRP systems.

Using iron compounds instead of copper compounds as mediators in ATRP is attractive from environmental aspects. Two systems with iron were investigated. Firstly, iron/EDTA was investigated as mediator as its redox properties are within a suitable range for controlled ATRP. The polymerization of styrene was heterogeneous, where the rate limiting step is the adsorption of the dormant species to the mediator surface. The polymerizations were not controlled and it is possible that they had some cationic character.

In the second iron system, the intention was to investigate how different ligands affect the properties of an ATRP system with iron. Due to competitive coordination of the solvent, DMF, the redox and polymeri­zation properties were not significantly affected by the ligands. The differences between normal and reverse ATRP of MMA, such as the degree of control, were the result of different FeIII speciation in the two systems.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2011. s. 64
Serie
Trita-CHE-Report, ISSN 1654-1081 ; 2011:021
Emneord
polymerization, controlled radical polymerization, atom transfer radical polymerization, kinetics, catalysis, electrochemistry
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-32104 (URN)978-91-7415-933-2 (ISBN)
Disputas
2011-04-29, Sal K2, Teknikringen 28, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Forskningsfinansiär
Swedish Research Council, 621-2005-6190
Merknad
QC 20110406Tilgjengelig fra: 2011-04-06 Laget: 2011-04-06 Sist oppdatert: 2011-04-13bibliografisk kontrollert

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