Coagulation properties of a magnetic fluid stabilized with polydimethylsiloxane

Abstract

The stability of a stabilized with polydimethylsiloxane (PDMS) magnetic fluid to alcohols of a saturated homologous series was investigated. We used alcohols with a linear molecular structure and their possible isomers. It was found that the solubility of the PDMS stabilized particles strongly depends on the length of the coagulant molecules and, quite unexpectedly, on the degree of isomerization. The first tested coagulants, ethanol and acetone, did not mix with PDMS stabilized magnetic fluid. The next member of the homologous series, linear propanol, is an effective coagulant that causes a sharp precipitation of particles. Meanwhile, with isopropanol, coagulation occurs very smoothly. The butanol isomers differ even more. Normal butanol causes the liquid to coagulate at a higher concentration than propanol. Whereas tert-butanol is mixed with PDMS stabilized magnetic fluid in any proportion. The last linear alcohol in the homologous series that can serve as a coagulant is hexanol-1. The next members of the homologous series no longer mix with the PDMS stabilized magnetic fluid. This is typical only for linear molecules. For example, 2ethylhexanol (isooctanol) perfectly dissolves PDMS stabilized particles. This property can be used to separate mixtures of isomers and linear molecules.