Advances in Research

Fluorescence Investigations of the Association of PEO-PBO-PEO Triblock Copolymers in the Presence of Ionic Surfactants SDS and CTAB

Zaheer Ahmad

Department of Chemistry, Quaid-i-Azam University, 45320, Islamabad, Pakistan

Muhammad Siddiq

Department of Chemistry, Quaid-i-Azam University, 45320, Islamabad, Pakistan

Asad Muhammad Khan

Department of Chemistry, COMSATS Institute of Information Technology, 22060-Abbottabad, KPK, Pakistan

Afzal Shah *

Department of Chemistry, Quaid-i-Azam University, 45320, Islamabad, Pakistan

*Author to whom correspondence should be addressed.

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Abstract

The interactions of triblock copolymers (TBP), E₃₀B₁₀E₃₀ and E₄₈B₁₀E₄₈ 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 (I₁/I₃), aggregation number, binding sites, binding constant and free energy of binding. In the presence of TBP, the I₁/I₃ 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

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