Effects of alcohols and diols on the phase behaviour of quaternary systems.
The aim of the current study was to investigate the effect of different co-surfactants on the phase behaviour of the pseudoternary system water:ethyl oleate:nonionic surfactant blend (sorbitan monolaurate/polyoxyethylene 20 sorbitan mono-oleate). Four aliphatic alcohols (1-propanol, 1-butanol, 1-hexanol and 1-octanol) and four 1, 2-alkanediols (1,2-propanediol, 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol) were used. The co-surfactant-free system forms two different colloidal structures, a water-in-oil microemulsion (w/o ME) and lamellar liquid crystals (LC) and two coarse dispersions, water-in-oil (w/o EM) and oil-in-water (o/w EM) emulsions. Microemulsion region area (%ME), liquid crystalline region area (%LC), amount of amphiphile blend required to produce a balanced microemulsion (%AMPH) and amount of water solubilised (%W) were used as assessment criteria to evaluate the co-surfactants. Seven calculated physico-chemical descriptors were used to represent the different co-surfactants. 1-butanol, 1,2-hexanediol and 1, 2-octanediol produced balanced MEs capable of solubilising a high percentage of both oil and water. A similarity was observed between the descriptors attributed to 1-butanol and 1,2-hexanediol. The requirements of a co-surfactant molecule to produce a balanced microemulsion were: HLB value 7.0-8.0, a carbon backbone of 4-6 atoms, percentage carbon of 60-65%, percentage oxygen of 20-30%, logP value 0.2-0.9 and log 1/S (S: aqueous solubility) close to zero.
Alany
R G
RG
School of Pharmacy, University of Otago, Dunedin, New Zealand.
Rades
T
T
Agatonovic-Kustrin
S
S
Davies
N M
NM
Tucker
I G
IG
D020001:1-Butanol / Q000737:chemistry; D020003:1-Octanol / Q000737:chemistry; D000433:1-Propanol / Q000737:chemistry; D000438:Alcohols / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003102:Colloids / Q000737:chemistry*; D003460:Crystallization; D004655:Emulsions / Q000737:chemistry; D006018:Glycols / Q000737:chemistry*; D006586:Hexanes; D000441:Hexanols / Q000737:chemistry; D009821:Oils; D019946:Propylene Glycol / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water
D000438:Alcohols; D003102:Colloids; D004655:Emulsions; D006018:Glycols; D006586:Hexanes; D000441:Hexanols; D009821:Oils; D013501:Surface-Active Agents; D014867:Water; C036260:1-hexanol; D019946:Propylene Glycol; D020001:1-Butanol; D000433:1-Propanol; D020003:1-Octanol; C119102:1,2-hexanediol