Stabilization of magnetic fluid with polydimethylsiloxane kills three birds with one stone

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 molecular weight of the coagulant 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 the most 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 tret-butanol mixes 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 do not mix with the PDMS stabilized magnetic fluid. This is typical only for linear molecules. For example, 2-ethylhexanol (isooctanol) perfectly dissolves PDMS stabilized particles. This property can be used to separate mixtures of isomers and linear molecules.