____________________________________________________________________________________________ *Corresponding author: E-mail: afzals_qau@yahoo.com; Advances in Research 2(2): 70-79, 2014, Article no. AIR.2014.002 SCIENCEDOMAIN international www.sciencedomain.org Fluorescence Investigations of the Association of PEO-PBO-PEO Triblock Copolymers in the Presence of Ionic Surfactants SDS and CTAB Zaheer Ahmad 1 , Muhammad Siddiq 1 , Asad Muhammad Khan 2 and Afzal Shah 1* 1 Department of Chemistry, Quaid-i-Azam University, 45320, Islamabad, Pakistan. 2 Department of Chemistry, COMSATS Institute of Information Technology, 22060-Abbottabad, KPK, Pakistan. Authors’ contributions This work was carried out in collaboration between all authors. Author ZA designed the study and performed the experimental work. Author MS offered explanation to the experimental results. Author AS managed the literature searches. All authors read and approved the final manuscript. Received 11 th September 2013 Accepted 11 th November 2013 Published 9 th January 2014 ABSTRACT The interactions of triblock copolymers (TBP), E 30 B 10 E 30 and E 48 B 10 E 48 with ionic surfactants, sodium dodecyl sulphate (SDS) and cetyl trimethyl ammonium bromide (CTAB) were investigated employing steady-state fluorescence spectroscopy (SSF). In this study pyrene was used as probe while cetyl pyridinium chloride (CPC) as a quencher. SSF was used for the calculation of first and third vibronic ratio (I 1 /I 3 ), aggregation number, binding sites, binding constant and free energy of binding. In the presence of TBP, the I 1 /I 3 was found more for SDS as compared to CTAB, predicting that the micro polarity of the solvent decreases in case of CTAB. The aggregation number of polymer/surfactant mixed systems was determined by SSF techniques. The suppression of the TBP association in the presence of surfactant concentration was also ensured by the same technique. Keywords: Block copolymer; aggregation number; free energy of binding; binding constant. OriginalResearchArticle