Optical Fiber: A Potential Method for Critical Micelle Concentration Measurement

Critical Micelle Concentration (CMC) of the surfactants is one of the most significant nominal properties of their solutions. This characteristic affects interfacial phenomena and bulk properties. In this study, two methods are used to measure the CMC of two ionic surfactants, CTAB and SDS.
The first technique is the drop profile analysis tensiometry (PAT) method and the second one is optical fiber technique. The purpose of this research is to find the potential of optical fiber method as a potential way to measure the CMC because it has been proved to be helpful for in-situ measurements of chemical properties. The spectrum width centre obtained by optical fiber and surface tension of measured by PAT at different concentrations of the surfactant in the solutions were compared together. The preliminary results demonstrated that there is a compliance between optical fiber and PAT techniques. However, the behaviour of two surfactants, one cationic and one anionic, was different in the optical fiber measurement. Based on the outcomes, it is important to consider the interactions between surfactant molecules and the solid surface of the fiber. The setup of the optical fiber should be in a closed volume chamber, and the hydrophilicity/hydrophobicity of the fiber should be determined.