SURFACTANT DISSOLUTION AND WATER SOLUBILIZATION IN CHLORINE-FREE LIQUEFIED GAS PROPELLANTS

The initial water content of a group of 15 pharmaceutically and toxico logically acceptable surfactants showed a tendency to increase with th e surfactant hydrophilic-lipophilic balance (HLB) value. Surfactant so lubility was determined in chlorine-free ''alternative propellants'' ( n-butane, propane, dimethyl ether [DME], 1,1,1,2-tetrafluoroethane (HF A-134a), and 1,1,1,2,3,3,3-heptafluoropropane [HFA-227ea], and trichlo romonofluoromethane [CFC-11] in the absence of cosolvents such as etha nol. Water-soluble surfactants such as Carbowax(R), Sentry(R), PEG 300 , Tween(R) 20 and Brij(R) 30 with high HLB values showed appreciable s olubility in HFA-134a and HFA-227ea. In systems containing greater tha n or equal to 80% propellant by weight, each single-phase propellant-s urfactant blend was screened for its ability to solubilize iodine and dissolve or solubilize water with increasing surfactant concentration. This screening was performed to investigate the possibility of formul ating high-volatility, single-phase systems with increased polarity an d solvency from these conventional excipients and vehicles. Ternary-ph ase diagrams show the regions of apparent single and multiple phase be havior in each system. Despite the increased polarity of the hydrofluo roalkanes (HFAs), appreciable water solubility was seen only with thes e surfactants in DME and in the hydrocarbons (HCs) n-butane and propan e.