title: Increasing the extensional viscosity of silicone oil reduces the tendency for emulsification.
abstract: OBJECTIVE
  The purpose was to study the emulsification of silicone oil tamponade agents that cause clinical complications. This study aimed to increase the emulsification resistance of silicone oil 1,000 to be at least as resistant as silicone oil 5,000 while maintaining the shear viscosity <5,000 mPa/s to aid injection and removal.
  
  
  METHODS
  High-molecular-weight (423 kDa) poly(dimethyl siloxane) was added to silicone oil 1,000 at 5% and 10% w/w concentration. The shear and extensional viscosity of 1,000 and 5,000, a 50:50 mixture of 1,000 and 5,000 and 5% and 10% w/w additive blends, respectively, of silicone oil were measured using capillary breakup extensional, rotational shear, and capillary extrusion rheometry. In vitro emulsification was assessed qualitatively after agitation using Pluronic F68 or a protein solution as the emulsion stabilizer.
  
  
  RESULTS
  The addition of high-molecular-weight polymer increased the extensional viscosity of the blends at high strain rates to levels equal to or greater than silicone oil 5,000. In all cases, the shear viscosity of the blends was lower than that of silicone oil 5,000. The additive blends were qualitatively as emulsification-resistant as silicone oil 5,000.
  
  
  CONCLUSIONS
  The addition of low concentrations of very-high-molecular-weight polymers of the same chemistry as the bulk oil has the potential to increase the emulsification resistance of the tamponade agents while maintaining ease of injection and removal.
authors.affiliation: Department of Clinical Engineering, School of Clinical Sciences, University of Liverpool, Liverpool, United Kingdom. rlw@liverpool.ac.uk
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Williams
authors.forename: Michael
authors.initials: M
authors.lastname: Day
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Garvey
authors.forename: Robert
authors.initials: R
authors.lastname: English
authors.forename: David
authors.initials: D
authors.lastname: Wong
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004655:Emulsions; D012827:Silicone Oils / Q000737:chemistry*; D014783:Viscosity
chemical_list: D004129:Dimethylpolysiloxanes; D004655:Emulsions; D012827:Silicone Oils; C013830:baysilon