Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
The goal of this study was to perform the distinction of the quality and structure of the bilayers created, by operating alternative surfactants in different compositions and concentrations. Previous researches presents that aggregations start to be formed in less than CMC (critical micelle concentration), but bilayers also seem to be created in even lower concentrations. In this experiment the compositions and concentrations which avail the achievement of bilayers were investigated. Surface tensiometer was employed to do the measurments.
The bilayers were formed in this work are vesicles which are sort of spherical bilayers AKA liposomes and they are the reason which caused the bluish color of the aqueous solutions. Other kinds like discs are not able to result the bluish color, so the hypothesis in this study was having vesicles in the solutions were made by surfactants.
The experiment was started by measuring surface tension of a mixture of SOS (sodium n-ctyl sulphate) plus DTAB (Dodecyltrimethylammonium) in DI water, from the a higher composition percentage of SOS and a lower composition percentage of DTAB. The procedure was continued by decreaasing in SOS composition and increasing in DTAB composition alternatively. All sets were repeated in identical concentrations from high to low. Bilayers in blue colors were possible to be recognized in lower than CMC in all sets. ST in all samples were measured.
In the next step the experiment repeated with the same material but in NaBr (50mM) solution instead of water. This time more sets were made and again measured by surface tensiometer. A pattern almost like the previous test was performed, but the solubility was much better in NaBr solution as expected and also bilayers were expected to be formed in higher concentrations.
The last sets were created for Gemini surfactants with the spacer of 6 and 3 and were measured by surface tensiometer. But muck lower solubility were identified, instead a much more huge aggregation was collected in all sets, both in DI water and NaBr solution.
Plotting the surface tension measurement (γ) vs. the Ln of concentrations of all sets confirms the investigation that surface tension almost remains the same over CMC, and CMC is the lowest concentration that free surfactants exist and below CMC all surfactants get to create aggregations. Also forming of bilayers happens as decreasing the concentration much better and it does not much depend on the composition.
2015. , 67 p.
Novel Dimeric Gemini Surfactant, Unimeric Surfactant, CMC, Bilayer, Surface Tension