Formation of nanoemulsion with long chain oil by W/O microemulsion dilution method

The preparation of nanoemulsions using long chain oil (C20 to C33) with remarkably small droplet size by microemulsion dilution method is generally difficult. In this work, a simple, W/O microemulsion dilution method was used to prepare O/W nanoemulsions with long chain oil in water/Span 80 − Tween 80/paraffin system. With the increase of dilution temperature from 40 to 80 °C, the emulsion droplet diameter decreased from 1.2 μm to 61 nm. The increase in the amount of dilution water led to the increase of the droplet diameter of nanoemulsions. Meanwhile, nanoemulsions with different charge, even positive charge, were also formed by adding various concentration of Jeffamine (D230) or cetyltrimethylammonium bromide (CTAB) in the W/O microemulsions. More importantly, paraffin nanoemulsions, formed in situ when W/O microemulsion was added to water-based drilling fluids, have effective lubrication and permeability plugging ability. Hence, formation of nanoemulsion by microemulsion dilution method demonstrated here is of great importance for practical applications.