Thermodynamic studies based on corresponding states theory for solutions of polystyrene in ethyl methyl ketone

Abstract

S U M M A R Y :The polymer solution theory on the corresponding state principle developed by FLORY was examined by comparing the thermodynamic parameters calculated theoretically with experimental results. The osmotic pressure of the polystyrene/ethyl methyl ketone system was determined for solutions of polymer concentrations 10 to 30 % at 10 to 55°C. Using X,, and Qlz parameters best fitting to these data, the calculated parameters were compared with experimental results. Both the entropy parameter vl and enthalpy parameter x~.~ were negative and decreased with increasing temperature. FLORY'S theory elucidates appreciably well the thermodynamic quantities with the use of the adjustable parameters XlZ and Q,,, but there seems to remain still some disagreement with experimental results. SHULTZ-FLORY'S method for determining the @-temperature was discussed based on this theory. Z U S A M M E N F A S S U N G :Die FLoRysche Theorie iiber das Prinzip der iibereinstimmenden Zustande fur Polymerlosungen wurde gepriift, indem die theoretisch berechneten Parameter mit experimentellen Ergebnissen verglichen wurden. Der osmotische Druck des Systems Polystyrol/Athylmethylketon wurde fur Polymerkonzentrationen zwischen 10 und 30 % bei 10 bis 55OC gemessen.Unter Verwendung der Parameter X l z und Q12, die den erhaltenen Daten am besten entsprachen, wurden die berechneten Parameter mit den experimentellen Ergebnissen verglichen. Der Entropie-Parameter v1 sowie der Enthalpie-Parameter ,yH,l waren negativ und nahmen mit steigender Temperatur ab. Mit Hilfe der anpassungsfahigen Parameter XI, und Q I z gibt die FLoRYsche Theorie die thermodynamischen Gro8en ziemlich gut wieder, obwohl eine geringe Abweichung von den experimentellen Ergebnissen zu bestehen scheint. Die SHULTZ-FLORYsche Methode zur Bestimmung der @-Temperatur wurde auf der Grundlage dieser Theorie diskutiert.

The prediction of the optimum compositions of a parenteral nanoemulsion system loaded with a low water solubility drug for the treatment of schizophrenia by artificial neural networks

“…16 A nanoemulsion is thermodynamically stable transparent (or translucent) system of oil, water, and surfactants, having a droplet size usually in the range of 20-200 nm. 17,18 It has been proven that a very small particle size of emulsion can provide effective encapsulation for delivery in the human body. 19 Nanoemulsions present good drug delivery and parenteral delivery due to their small nanometer size particles, biocompatibility, relative stability, ability to solubilize high quantities of hydrophobic compounds, ability to reduce the toxicity of drugs, and ability to protect drugs from hydrolysis and enzymatic degradation under physiological conditions.…”