Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly( tert

This work presented the surface modification of magnetite nanoparticle (MNP) with poly[(t-butyl acrylate)-stat-(poly(ethylene glycol) methyl ether methacrylate)] copolymers (P[(t-BA)-stat-PEGMA]) via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP). Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp.) such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR). The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC) indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM) revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA) homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA) and their magnetic properties were investigated via vibrating sample magnetometry (VSM)

Magnetite Nanoparticles Functionalized with Thermoresponsive Polymers as a Palladium Support for Olefin and Nitroarene Hydrogenation

A thermoresponsive and recyclable nanomaterial was synthesized by surface modification of magnetite nanoparticles (MNPs) with poly(N-isopropylacrylamide-co-diethylaminoethyl methacrylate) (P(NIPAAm-co-DEAEMA)), having PNIPAAm as a thermoresponsive moiety and PDEAEMA for catalyst binding. Palladium (Pd) nanoparticles were incorporated into this material, and the resulting nanocatalyst was efficient in the hydrogenation of olefins and nitro compounds with turnover frequencies (TOFs) up to 750 h–1. Consistent catalytic activity in 10 consecutive runs was observed when performing the hydrogenation at 45 °C, i.e., above the lower critical solution temperature (LCST) of the copolymer (37 °C), followed by cooling to 15 °C, i.e., below the LCST of the copolymer

Multiresponsive Poly(N-Acryloyl glycine)-Based Nanocomposite and Its Drug Release Characteristics

pH- and thermoresponsive nanocomposite composed of poly(N-acryloyl glycine) (PNAG) matrix and magnetite nanoparticle (MNP) was synthesized and then used for drug controlled release application. The effects of crosslinkers, e.g., ethylenediamine and tris(2-aminoethyl)amine, and their concentrations (1 and 10 mol%) on the size, magnetic separation ability, and water dispersibility of the nanocomposite were investigated. The nanocomposite crosslinked with tris(2-aminoethyl)amine (size ranging between 50 and 150 nm in diameter) can be rapidly separated by a magnet while maintaining its good dispersibility in water. It can respond to the pH and temperature change as indicated by the changes in its zeta potential and hydrodynamic size. From the in vitro release study, theophylline as a model drug was rapidly released when the pH changed from neutral to acidic/basic conditions or when increasing the temperature from 10°C to 37°C. This novel nanocomposite showed a potential application as a magnetically guidable vehicle for drug controlled release with pH- and thermotriggered mechanism

Recyclable magnetite nanoparticle coated with cationic polymers for adsorption of DNA

<p>Magnetite nanoparticle (MNP) grafted with a cationic copolymer between poly(2-(<i>N,N</i>-diethylamino) ethyl methacrylate) and poly(poly(ethylene glycol) methyl ether methacrylate)) for efficient and recyclable adsorption of 5’-fluorescein-tagged DNA (FAM-dT₉) was prepared. MNP having highest degree of positive charge (+32.1 ± 1.9 mV) retained 100% adsorption of FAM-dT₉ during eight adsorption–separation–desorption cycles. The MNP having lower degree of positive charge showed a slight decrease in adsorption percentages (94–98% adsorption) after multiple recycling processes. This biocompatible hybrid material with charged surface and magnetic-responsive properties might be applicable for use as a nanosolid support for efficient and facile separation of various bioentities.</p

Anionic polymer-coated magnetic nanocomposites for immobilization with palladium nanoparticles as catalysts for the reduction of 4-nitrophenol

Abstract This study focuses on the synthesis of magnetite nanoparticles (MNP) coated with poly(poly(ethylene glycol) methacrylate) (PPEGMA) and/or poly(acrylic acid) (PAA) to anchor palladium nanoparticles (Pd) for their application as recyclable catalysts in the reduction of 4-nitrophenol (4NP). It was hypothesized that the abundance of oxygen atoms in PPEGMA enabled coordination with the Pd and provided good water dispersibility of the nanocomposites, while anionic PAA stabilized Pd and reduced the catalyst aggregation through electrostatic repulsion. Three different polymer coatings on MNP (PAA, PPEGMA, and PAA-co-PPEGMA polymers) were investigated to assess their influence on both the catalytic activity and reusability of the catalysts. Transmission electron microscopy (TEM) analysis indicated the distribution of spherical Pd nanoparticles (3–5 nm in diameter) and MNP (9–12 nm in diameter). Photocorrelation spectroscopy (PCS) revealed an average hydrodynamic size of the catalysts ranging from 540 to 875 nm in diameter, with a negative charge on their surface. The Pd content of the catalysts ranged from 4.30 to 6.33% w/w. The nanocomposites coated with PAA-co-PPEGMA polymers exhibited more favorable catalytic activity in the 4NP reduction than those coated with PAA or PPEGMA homopolymers. Interestingly, those containing PAA (e.g., PAA and PAA-co-PPEGMA polymers) exhibited good reusability for the 4NP reduction with a slight decrease in their catalytic performance after 26 cycles. This indicates the important role of carboxyl groups in PAA in maintaining high tolerance after multiple uses. Graphical abstrac