POLYACRYLIC ACID-COATED IRON OXIDE MAGNETIC NANOPARTICLES: THE POLYMER MOLECULAR WEIGHT EFFECT

LAURA M. SANCHEZ; DANIEL A. MARTIN; VERA A. ALVAREZ; JIMENA S. GONZALEZ

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 543 p. 28 - 37

0927-7757

Magnetic nanoparticles (MNPs), in particular, magnetic iron oxide-based nanoparticles were found to be usefulas catalysts and as devices for data storage, environmental remediation and several biomedical applications, dueto their excellent properties, such as biocompatibility and high magnetic moment. Polyacrylic acid (PAA) is aweak polyelectrolyte that can be used to stabilize the MNPs. To the best of our knowledge, the influence of PAAmolecular weight and PAA concentration over the magnetic and structural properties of iron oxide nanoparticleshas not been previously reported. The aim of this paper is to describe the differences evidenced in the propertiesof different magnetic materials by using PAA for iron oxides stabilization by one-pot coprecipitation synthesis.Iron oxide-based magnetic nanoparticles stabilized by polyacrylic acid (PAA) polymers were efficiently preparedand exhaustively characterized. The influence on the employment of two different low PAA molecular weights,Mw 1800 g/mol and 5000 g/mol, in three different iron salts: PAA ratios was analyzed. In summary, the mainresults showed that: for a certain PAA reactor feed higher oligomer quantities are present in MNPs as higher isthe involved molecular weight of the polymeric chain; when molecular weight raises the contribution of loopsand tails also does it, allowing having higher polymer contents. For both PAA?s Mw employed as the adsorbedPAA increases particles hydrodynamic diameters decreases, and their distribution becomes narrower; the PAAadsorbs onto iron oxides by chemisorption (the most probable interaction is the bidentate bridging). For thestudied cases z potential values depend much more on the PAA?s quantity adsorbed onto the iron oxides than onthe PAA?s Mw. MNPs are superparamagnetic and choosing the right shape of particle distribution is not central for getting estimates of the magnetization saturation, the average particle diameter and its standard deviation,while better fits are found with Normal and Log-Normal particle size distributions.