Synthesis of Polymer Grafted Magnetite Nanoparticle with the Highest Grafting Density via Controlled Radical Polymerization

Abstract

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/nm2for the rapidly polymerizing benzyl methacrylate. In contrast, for the less rapidly polymerizing styrene, the grafting density was found to be nearly 0.7 chain/nm2. 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.

Magnetic Fe3O4@poly(propylene fumarate-co-ethylene glycol) core–shell biomaterials

“…This hints that most of the NHS esters of the copolymer network are already covalently bounded to microparticles, and further amount of MagP®-NH 2 would not lead to higher GD values. Similar behaviour has been reported for poly(hydroxyethyl methacrylate)-graed magnetite nanoparticles, 45 where GD saturated above a certain amount of monomer concentration.…”

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“…The second factor is that the polymerization rate is fast in comparison to conformational relaxation of the growing chains. The rate of polymerization may have a direct influence of the grafting density of the polymer brush as previously reported in literature …”

Two Non‐covalent Methods to Decorate Nanoparticles with Block Copolymers

“…Here, the process is not really limited by the diffusion of reactive species (monomers) to the surface and, therefore, thick polymer brushes with high grafting density (>1 chain/nm 2 ) can be obtained. [ 5 ] Controlled/"living" free-radical polymerizations like atom transfer radical polymerization (ATRP) or reversible addition fragmentation chain transfer (RAFT) usually offer a good control over the brush thickness and architecture. [ 6 ] The physical adsorption of polymers remains the most straightforward approach to build a (co)polymer layer onto a substrate.…”

“…In addition, the “grafting to” approach does not permit to control the chain orientation, which implies the impossibility to form ordered layers as noticed by Rakhmatullina et al Such limitations can be overcome with the “grafting from” technique, which involves the covalent attachment of an initiator onto the substrate, followed by in situ surface‐initiated polymerization to obtain a tethered polymer brush. Here, the process is not really limited by the diffusion of reactive species (monomers) to the surface and, therefore, thick polymer brushes with high grafting density (>1 chain/nm 2 ) can be obtained . Controlled/“living” free‐radical polymerizations like atom transfer radical polymerization (ATRP) or reversible addition fragmentation chain transfer (RAFT) usually offer a good control over the brush thickness and architecture .…”