Polymer-encapsulated silver nanoparticles were synthesized and sterically stabilized by a new core-shell type system consisting of poly(S-alt-MA)-graft- PMMA copolymer that acts as a scaffold for the synthesis of size confined nanoparticles. The graft copolymer is synthesized via ambient temperature ATRP using the CuBr/PMDETA catalytic system at ambient temperature. The graft copolymer is hypothesized to function as a scaffold with the anhydride part interacting strongly with the silver ions, while the PMMA graft functions as a polymer brush that stabilizes the dispersion and prevents the particle aggregation due to a 'polymer brush effect'. UV absorption and TEM studies confirm that the synthesized silver composite particles have a core-shell structure. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

R. Dhamodharan

Department Of Chemistry

ABS resins

Agglomeration

ATOM TRANSFER RADICAL POLYMERIZATION

BRUSHES

Copolymerization

Free radical reactions

Graft copolymers

Grafting (chemical)

Metal ions

Monomers

Nanoparticles

Nanostructured materials

Nanostructures

Organic polymers

Photoresists

Plastic products

Probability density function

Scaffolds

Shells (structures)

Silver

Temperature

Ambient temperatures

ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

CATALYTIC SYSTEMS

CONFINED NANOPARTICLES

Core shells

Core-shell structures

CORESHELL POLYMERS

PARTICLE AGGREGATIONS

PARTICLE STABILITIES

PMMA GRAFTS

POLYMER BRUSHES

SILVER COMPOSITE PARTICLES

Silver ions

Silver nanoparticles

Synthesis of

TYPE SYSTEMS

UV ABSORPTIONS

Polymers

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Macromolecular Rapid Communications

Well defined graft copolymers are prepared by "grafting from" atom transfer radical polymerization (ATRP) at room temperature (30°C). The experiments were aimed at grafting methacrylates and styrene at latent initiating sites of polystyrene. For this purpose, the benzylic hydrogen in polystyrene was subjected to allylic bromination with Af-bromosuccinimide and azobisisobutrylnitirle to generate tertiary bromide ATRP initiating sites (Br-C-PS). The use of Br-C-PS with lesser mol % of bromide initiating groups results in better control and successful graft copolymerization. This was used to synthesize a series of new graft copolymers such as PS-g-PBnMA, PS-g-PBMA, PS-g-GMA, and PS-g-(PMMA-b-PtBA) catalyzed by CuBr/PMDETA system, in bulk, at room temperature. The polymers are characterized by GPC, NMR, FTIR, TEM, and TGA. Graft copolymerization followed by block polymerization enabled the synthesis of highly branched polymer brush, in which the grafting density can be adjusted by appropriate choice of bromide concentration in the polystyrene. © 2007 Wiley Periodicals, Inc.

Journal of Polymer Science, Part A: Polymer Chemistry

Grafting of methacrylates and styrene on to polystyrene backbone via a "grafting from" ATRP process at ambient temperature

The synthesis of methyl methacrylate (MMA) brush from the surface of magnetite nanoparticles (core-shell structure), from initiator moieties anchored covalently to the nanoparticles, via room temperature atom transfer radical polymerization (ATRP) is described. The surface-initiated polymerization was carried out from a surface-confined initiator containing a 2-bromoisobutyrate moiety with Cu(l)Br/PMDETA catalytic system. The initiator moiety was covalently anchored to the nanoparticles via a two step modification reaction scheme. Controlled polymerization was observed if ethyl-2-bromoisobutyrate (2-EiBrB) was added as a free/sacrificial initiator. A linear increase of molecular weight and a narrow molecular weight distribution of the PMMA formed in solution, provide evidence for a controlled surface-initiated polymerization, leading to surface-attached polymer brushes under mild conditions. The grafted PMMA provides good stability and dispersibility for the nanoparticles in organic solvents. Copyright © 2006 American Scientific Publishers All rights reserved.

Journal of Nanoscience and Nanotechnology

Surface-initiated atom transfer radical polymerization of methyl methacrylate from magnetite nanopartictes at ambient temperature

Poly(methyl methacrylate) (PMMA) brushes are grown by surface-initiated atom transfer radical polymerization on silicon surfaces at various polymerization temperatures. Kinetic studies show that the layer thickness scales linearly with the degree of polymerization of the polymers under some conditions, indicating a constant graft density of the surface-attached chains. At high temperatures, the layer growth is a controlled process only for short reaction times, and after a rapid increase, the film growth levels off, and a constant thickness is obtained. At lower reaction temperatures, polymers with a lower polydispersity are obtained, but at the expense of a much slower growth rate. Accordingly, intermediate temperatures yield the highest film thickness on experimentally feasible timescales. The reinitiation of these surface-grafted PMMA chains at room temperature to either extend the chains or grow a chemically different polyglycidylmethacrylate block demonstrates the presence of active ends and the living nature of the surface-grafted PMMA chains. © 2006 Wiley Periodicals, Inc.

Growth of poly(methyl methacrylate) brushes on silicon surfaces by atom transfer radical polymerization

The ability to do very rapid bulk atom transfer radical polymerization (ATRP) of benzyl methacrylate using a CuX/PMDETA complex at room temperature was demonstrated in this study. The experimental conditions required to synthesize low- and high-molecular-weight poly(benzyl methacrylate) with low polydispersity are reported here. The controlled/living nature of the polymerization was demonstrated through kinetic studies, and chain-extension studies. © 2004 Wiley Periodicals, Inc.

Very Rapid Copper-Mediated Atom Transfer Radical Polymerization of Benzyl Methacrylate at Ambient Temperature

Novel bifunctional initiators [1,1′-Bi-2-naphthol bis(2-bromo-2-methylpropionate); (R)-, (S)-, and racemic-] were synthesized from the esterification of 1,1′-bi-2-naphthol and used as initiators in atom transfer radical polymerization (ATRP) in conjunction with N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA), and copper (I) bromide or copper (I) chloride. The initiators synthesized were completely characterized by UV, FTIR, NMR, and Mass spectroscopies. A detailed investigation of the ATRP of methyl methacrylate (MMA) with the bifunctional initiators (BBiBN) along with CuBr or CuCl/PMDETA catalyst system in anisole was carried out at 30°. Thus, MMA polymerization is shown to proceed with first-order kinetics, with predicted molecular weight, and narrow polydispersity indices. The ATRP of glycidyl methacrylate (GMA) and tert-butyl acrylate (tBA) were also performed with BBiBN initiator in conjunction with CuBr/PMDETA catalyst system. The polymerization of GMA was carried out at 30°C, but tBA was polymerized at 60°C. Gel permeation chromatography (GPC), FTIR, NMR, UV spectroscopies, and TGA were used for the characterization of the polymers synthesized. © 2004 Wiley Periodicals, Inc.

ATRP of methyl methacrylate using a novel binol ester-based bifunctional initiator

Synthesis of silver nanoparticles using a novel graft copolymer and enhanced particle stability via a "polymer brush effect"

Journal	Macromolecular Rapid Communications
ISSN	10221336
Open Access	No