Magnetizable colloids on strongly polar carriers – preparation and manifold characterization

Comparative analysis of the structure of sterically stabilized ferrofluids on polar carriers by small-angle neutron scattering

“…Approximate volume fraction of the surfactants in the samples was 1.7 times greater than that of magnetite [4]. Precise determination of this value, as well as the magnetite content by mass density in the case of doubly stabilized ferrofluids is a difficult problem, since the concentration ratio between absorbed and free surfactants is unknown.…”

“…Details of the preparation procedure are fully covered in previous works [3,4,16,17]. The samples with pentanol (SPENT) and methyl-ethyl-ketone (SM) carriers were prepared by dispersing oleic acid monolayer covered magnetite nanoparticles, extracted from the same petroleum based primary magnetic fluid.…”

“…The samples with pentanol (SPENT) and methyl-ethyl-ketone (SM) carriers were prepared by dispersing oleic acid monolayer covered magnetite nanoparticles, extracted from the same petroleum based primary magnetic fluid. For redispersion of particles in the organic polar carriers technical grade dodecylbenzenesulphonic acid (DBS) was used as secondary surfactant, according to the carrier liquid exchange procedure described in [4]. The water based samples SW1, SW2 and SW3 were individually prepared, using different combination of surfactants to form the stabilizing bilayer on magnetite nanoparticles [4].…”

“…For redispersion of particles in the organic polar carriers technical grade dodecylbenzenesulphonic acid (DBS) was used as secondary surfactant, according to the carrier liquid exchange procedure described in [4]. The water based samples SW1, SW2 and SW3 were individually prepared, using different combination of surfactants to form the stabilizing bilayer on magnetite nanoparticles [4]. Taking into account the biological aspect, in the case of sample SW3 the procedure was probed for the carrier of natural origin, which is sap-water extracted from plants containing some amount of natural salts.…”

“…The problem can be solved through the double layer sterical stabilization method, involving a primary surfactant layer chemisorbed on the particle surface and a secondary surfactant of the same or another type (depending on adsorption properties), physically adsorbed on the previous layer. In recent years, a certain progress in the synthesis of stable polar ferrofluids with large volume fractions of magnetic materials using double-layer sterical stabilization method (e.g., pentanol-based ferrofluid, ϕ m ∼ 20%) has been achieved [3,4]. In this respect, the structure of this type of ferrofluids and its comparison with that of non-polar ferrofluids is of current interest.…”