The atom-transfer radical polymerization of methyl methacrylate at room temperature starting from monolayers of initiators, which are covalently anchored to silicon substrates, is described. The control of layer thickness and molecular weight, a constant graft density, and a narrow molecular weight distribution of the polymers produced provide evidence for a controlled surface-initiated polymerization, and dense surface-attached polymer brushes on the SiO2 surfaces are obtained under mild reaction conditions.

R. Dhamodharan

Department Of Chemistry

Ayothi Ramakrishnan

poly(methyl methacrylate)

polymer

Silicon

silicon dioxide

article

chemical reaction

density

Growth

Molecular weight

Polymerization

Room temperature

synthesis

Thickness

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

Controlled Growth of PMMA Brushes on Silicon Surfaces at Room Temperature

Macromolecular Rapid Communications

We demonstrate, for the first time, the synthesis of model poly(benzyl methacrylate) [P(BnMA)] brushes of very high thickness (>300 nm) on silicon wafer. P(BnMA) brush is also synthesized from the surface of silica nanoparticles, from a covalently anchored initiator monolayer, using ambient temperature ATRP. The kinetic studies and block copolymerization from the surface anchored P(BnMA)-Br macroinitiator showed that the polymerization was controlled in nature. AFM, ellipsometry, and water contact angle were used for the characterization of the polymer brush. The grafting density of the P(BnMA) brush, formed by immersion in a dilute monomer solution, was relatively less (∼11% less) in comparison to that obtained by immersion in neat monomer under similar conditions. The P(BnMA)-Br macroinitiator brushes were used to synthesize P(BnMA-b-S) diblock copolymer brushes by the ATRP of styrene at 95 °C. The P(BnMA-b-S) brushes showed stimulus response to a selective solvent and various nanopatterns were observed according to the composition of the block copolymer. © 2011 American Chemical Society.

Langmuir

Synthesis and morphological study of thick benzyl methacrylate-styrene diblock copolymer brushes

The surface-initiated ATRP of benzyl methacrylate, methyl methacrylate, and styrene from magnetite nanoparticle is investigated, without the use of sacrificial (free) initiator in solution. It is observed that the grafting density obtained is related to the polymerization kinetics, being higher for faster polymerizing monomer. The grafting density was found to be nearly 2 chains/nm 2 for the rapidly polymerizing benzyl methacrylate. In contrast, for the less rapidly polymerizing styrene, the grafting density was found to be nearly 0.7 chain/nm 2. It is hypothesized that this could be due to the relative rates of surface-initiated polymerization versus conformational mobility of polymer chains anchored by one end to the surface. An amphiphilic diblock polymer based on 2-hydroxylethyl methacrylate is synthesized from the polystyrene monolayer. The homopolymer and block copolymer grafted MNs form stable dispersions in various solvents. In order to evaluate molecular weight of the polymer that was grafted on to the surface of the nanoparticles, it was degrafted suitably and subjected to gel permeation chromatography analysis. Thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to confirm the grafting reaction. © to the authors 2009.

Fulltext

Nanoscale Research Letters

Synthesis of polymer grafted magnetite nanoparticle with the highest grafting density via controlled radical polymerization

Poly(methyl methacrylate) in the brush form is grown from the surface of magnetite nanoparticles by ambient temperature atom transfer radical polymerization (ATATRP) using a phosphonic acid based initiator. The surface initiator was prepared by the reaction of ethylene glycol with 2-bromoisobutyrl bromide, followed by the reaction with phosphorus oxychloride and hydrolysis. This initiator is anchored to magnetite nanoparticles via physisorption. The ATATRP of methyl methacrylate was carried out in the presence of CuBr/PMDETA complex, without a sacrificial initiator, and the grafting density is found to be as high as 0.90 molecules/nm 2. The organic-inorganic hybrid material thus prepared shows exceptional stability in organic solvents unlike unfunctionalized magnetite nanoparticles which tend to flocculate. The polymer brushes of various number average molecular weights were prepared and the molecular weight was determined using size exclusion chromatography, after degrafting the polymer from the magnetite core. Thermogravimetric analysis, X-ray photoelectron spectra and diffused reflection FT-IR were used to confirm the grafting reaction.

Grafting of poly(methyl methacrylate) brushes from magnetite nanoparticles using a phosphonic acid based initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP)

In this work, we describe the use of hydridosilanes for the attachment of polymer monolayers to SiO2 surfaces. In one approach, first a benzophenone group containing hydridosilane is self-assembled on the SiO 2 surface followed by photochemical attachment of polymer chains deposited onto the monolayer. In a second approach an ATRP initiator is self-assembled to the substrate surface, again using hydridosilane anchor groups. The surface-attached initiator groups are subsequently used for the growth of surface-attached polymer chains in a surface-initiated polymerization reaction. It is shown that, while chlorosilanes require rather stringent exclusion of moisture during self-assembly, the hydridosilanes are rather robust and functional monolayers are formed even under ambient conditions. That in turn allows for the use of silanes in standard printing processes. In contrast to printing of chlorosilanes, which must be carried out under strictly anhydrous conditions, printing of hydridosilanes thus represents a simple and versatile technique for the generation of microstructured surfaces. © 2008 American Chemical Society.

Macromolecules

A robust method for the immobilization of polymer molecules on SiO 2 surfaces

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.

Journal of Polymer Science, Part A: Polymer Chemistry

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

Chemical Reviews

Atom Transfer Radical Polymerization

Journal of the American Chemical Society

Atom Transfer Radical Polymerization from Nanoparticles:  A Tool for the Preparation of Well-Defined Hybrid Nanostructures and for Understanding the Chemistry of Controlled/“Living” Radical Polymerizations from Surfaces

Advanced Materials

Controlled Surface-Initiated Polymerizations in Aqueous Media

Surface-Initiated Atom Transfer Radical Polymerization on Gold at Ambient Temperature

Using Atom Transfer Radical Polymerization To Amplify Monolayers of Initiators Patterned by Microcontact Printing into Polymer Brushes for Pattern Transfer

Controlled growth of PMMA brushes on silicon surfaces at room temperature

Journal	Macromolecular Rapid Communications
ISSN	10221336
Open Access	No