Synthesis of Polystyrene-Coated Superparamagnetic and Ferromagnetic Cobalt Nanoparticles

Abstract

Polystyrene-coated cobalt nanoparticles (NPs) were synthesized through a dual-stage thermolysis of cobalt carbonyl (Co2(CO)8). The amine end-functionalized polystyrene surfactants with varying molecular weight were prepared via atom-transfer radical polymerization technique. By changing the concentration of these polymeric surfactants, Co NPs with different size, size distribution, and magnetic properties were obtained. Transmission electron microscopy characterization showed that the size of Co NPs stabilized with lower molecular weight polystyrene surfactants (Mn = 2300 g/mol) varied from 12–22 nm, while the size of Co NPs coated with polystyrene of middle (Mn = 4500 g/mol) and higher molecular weight (Mn = 10,500 g/mol) showed little change around 20 nm. Magnetic measurements revealed that the small cobalt particles were superparamagnetic, while larger particles were ferromagnetic and self-assembled into 1-D chain structures. Thermogravimetric analysis revealed that the grafting density of polystyrene with lower molecular weight is high. To the best of our knowledge, this is the first study to obtain both superparamagnetic and ferromagnetic Co NPs by changing the molecular weight and concentration of polystyrene through the dual-stage decomposition method.

A novel and efficient method for synthesizing magnetic PS-PMMA@Fe3O4 microspheres for protein separation and detection

“…The automatic chemiluminescent immunoassay greatly shortens the detection time of samples and improves the repeatability of detection methods for a large number of samples through clinical analysis, environmental analysis,food analysis and other elds of [1][2][3][4][5] .Magnetic microbeads have shown great promise in immunoassay equipment, because of the use of magnetic microbeads as a separation tool in chemical immunoassay platforms and as special biomolecular immobilization carriers [6][7][8][9] . Binding to surface-modifying groups, such as carboxyl and amino groups, can provide a high density of antibodies or proteins, increasing the ease of attachment to proteins, and target antigens can be directly captured, easily isolated, and immunoanalyzed [10][11][12] .…”

An efficient method for the preparation of magnetic Co3O4 nanoparticles and the study of their catalytic application

“…Some recent reports in this matter are Co 3 O 4 -SiO 2 nanocomposites for CO oxidation (Jia et al, 2011), Co 3 O 4 @SiO 2 NPs for the preparation of 3,4-dihydroquinoxalins (Ghasemzadeh et al, 2016), Co 3 O 4 for the reduction of 4nitrophenols (Al Nafiey et al, 2017), Co 3 O 4 @SiO 2 for the preparation of indazoles (Ghasemzadeh et al, 2017), Co 3 O 4 NPs as a photocatalyst for methylene blue degradation (Vennela et al, 2019), and Co 3 O 4 @SiO 2 core/shell-nylon as an adsorbent for the removal of Congo red from wastewater (Mohammadi et al, 2020). There are also several methods for the synthesis of these NPs, including sol-gel, chemical pyrolysis, microemulsion, chemical vapor deposition (CVD), coprecipitation, microwave, decomposition of organic precursors, and hydrothermal methods (He et al, 2004;Yoshikawa et al, 2004;Ştefănescu et al, 2008;Ozkaya et al, 2009;Gupta et al, 2011;Alagiri et al, 2013;Salavati-Niasari and Khansari, 2014;Gopinath et al, 2016;Diallo et al, 2017;Izu et al, 2017;Jamil et al, 2018;Tan et al, 2018;Yetim, 2021). However, some of the aforementioned methods face problems of high reaction temperature, high pressure, and the use of expensive precursors.…”

Preparation of Functionalized Magnetic Polystyrene Microspheres and Their Application in Food Safety Detection

“…These microspheres have both the functional properties of polymer materials and the magnetic response of inorganic nanoparticles. They can attract functional groups (such as amino, carboxyl, and aldehyde) through modifying polymer materials, so as to graft enzymes, catalysts and other guest molecules [ 24 ]. At the same time, magnetic polymer composite microspheres can also realize magnetic separation and directional movement under the action of external magnetic fields.…”