Polymer chains grafted “to” and “from” layered silicate clay platelets

Mittal, Vikas

doi:10.1016/j.jcis.2007.05.046

Cited by 49 publications

(21 citation statements)

References 50 publications

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“…[85] The exfoliation of montmorillonite-layered silicate was possible by immobilization of an azo initiator and polymerization of lauryl methacrylate in the presence of SG1. [86] Thermogravimetry was used by Billon and co-workers to study the effect of the size of an initiator system on its grafting density (Si particles). [87] Therefore, initiators for the uni-and bimolecular initiation of NMP and an ATRP initiator were compared.…”

Section: Polymer Brushes By Unimolecular-initiated Polymerization Usimentioning

confidence: 99%

Polymer Brushes by Nitroxide‐Mediated Polymerization

Brinks

Studer

2009

Macromol. Rapid Commun.

122

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This review article describes the preparation of polymer brushes by nitroxide-mediated radical polymerization using either the 'grafting to' or the 'grafting from' approach. The use of TEMPO as a classical initiator is intensively described. More sophisticated nitroxides are also included in the discussion. Brush formation on flat surfaces such as wafers and also on particles is reported. Finally, some applications of polymer brushes are presented.

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Section: Polymer Brushes By Unimolecular-initiated Polymerization Usimentioning

confidence: 99%

Polymer Brushes by Nitroxide‐Mediated Polymerization

Brinks

Studer

2009

Macromol. Rapid Commun.

122

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“…Free radical polymerization of styrene with azo bis(iso -butyronitrile) as initiator led to the generation of exfoliated polystyrene -clay nanocomposites. Mittal [43] also reported the partial exchange of fi ller surface with methacryloxyethyltrimethylammonium chloride and the remaining surface with nonreactive modifi cation as shown in Figure 1.19 . The free radical polymerization of lauryl methacrylate in the presence of modifi ed montmorillonite led to the tethering of poly(lauryl methacrylate) chains to the fi ller surface.…”

Section: In -Situ Synthesis Of Polymer Nanocompositesmentioning

confidence: 95%

In‐situ Synthesis of Polymer Nanocomposites

Mittal

2011

In‐Situ Synthesis of Polymer Nanocomposites

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IntroductionIt was the pioneering work of Toyota researchers toward the development of polymeric nanocomposites in the early 90s [1,2] , in which electrostatically held 1 -nmthick layers of the layered aluminosilicates were dispersed in the polyamide matrix on a nanometer level, which led to an exponential growth in the research in these layered silicate nanocomposites. These nanocomposites were based on the in -situ synthesis approach in which monomer or monomer solution was used to swell the fi ller interlayers followed by polymerization. Subsequently, Giannelis and coworkers [3,4] also reported the route of melt intercalation for the synthesis of polymer nanocomposites.Montmorillonite has been the most commonly used layered aluminosilicate in most of the studies on polymer nanocomposites. The general formula of montmorillonites is M x (Al 4 − x Mg x )Si 8 O 20 (OH) 4 [5, 6] . Its particles consist of stacks of 1 -nmthick aluminosilicate layers (or platelets) with a regular gap in between (interlayer). Each layer consists of a central Al -octahedral sheet fused to two tetrahedral silicon sheets. In the tetrahedral sheets, silicon is surrounded by four oxygen atoms, whereas in the octahedral sheets, aluminum atom is surrounded by eight oxygen atoms. Isomorphic substitutions of aluminum by magnesium in the octahedral sheet generate negative charges, which are compensated for by alkaline -earth -or hydrated alkali -metal cations. Owing to the low charge density (0.25 -0.5 equiv. mol − 1 ) of montmorillonites, a larger area per cation is available on the surface that leads to a lower interlayer spacing in the modifi ed montmorillonite after surface ion exchange with alkyl ammonium ions. On the contrary, the minerals with high charge density (1 equiv. mol − 1 ) like mica have much smaller area per cation and can lead to much higher basal plane spacing after surface modifi cation; however, owing to very strong electrostatic forces present in the interlayers due to the increased number of ions, these minerals do not swell in water and thus do not allow the cation exchange. In contrast, aluminosilicates with medium charge densities of 0.5 -0.8 equiv. mol − 1 like vermiculite offer a potential of partial swelling in water and cation exchange that can lead to much higher basal plane spacing in In-situ Synthesis of Polymer Nanocomposites, First Edition. Edited by Vikas Mittal.

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“…Surface reactions on the clay have been studied extensively so as to generate polymer chains and achieve much higher basal plane spacing values; this would otherwise be diffi cult to achieve via the exchange of preformed long chains, owing to problems of solubility and steric hindrance. The two forms of polymerization reaction are represented in Figure 1.11 a: (i) polymerization " to " the surface, which is generally achieved by exchanging a monomer on the fi ller surface, followed by its polymerization with the external monomer; and (ii) polymerization " from " the surface, in which generally an initiator is bound ionically to the fi ller surface, which then is used to initiate the polymerization of an externally added monomer [38] . Other than these two options, a number of other possibilities of surface reactions exist, including surface esterifi cation .…”

Section: Advances In Filler Surface Modifi Cationsmentioning

confidence: 99%

Polymer Nanocomposites: Synthesis, Microstructure, and Properties

Mittal

2010

Optimization of Polymer Nanocomposite Properties

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Polymer chains grafted “to” and “from” layered silicate clay platelets

Cited by 49 publications

References 50 publications

Polymer Brushes by Nitroxide‐Mediated Polymerization

Polymer Brushes by Nitroxide‐Mediated Polymerization

In‐situ Synthesis of Polymer Nanocomposites

Polymer Nanocomposites: Synthesis, Microstructure, and Properties

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