title: pH-switchable structural evolution in aqueous surfactant-aromatic dibasic acid system.
abstract: Structural transitions triggered by pH in an aqueous micellar system comprising of a cationic surfactant (cetylpyridinium chloride) and an aromatic dibasic acid (phthalic acid) was investigated. Reversible switching between liquid-like and gel-like states was exhibited by the system on adjusting the solution pH. Self-assembled structures, responsible for the changes in flow properties were identified using rheology, light scattering techniques and cryogenic Transmission Electron Microscopy (cryo-TEM). High-viscosity, shear-thinning behavior and Maxwell-type dynamic rheology shown by the system at certain pH values suggested the growth of spheroidal/short cylindrical micelles into long and entangled structures. Light scattering profiles also supported the notion of pH-induced microstructural transitions in the solution. Cryo-TEM images confirmed the presence of spheroidal/short cylindrical micelles in the low-viscosity sample whereas very long and entangled thread-like micelles in the peak viscosity sample. pH-dependent changes in the micellar binding ability of phthalic acid is proposed as the key factor regulating the morphological transformations and related flow properties of the system.
authors: Department of Chemistry, NIT Calicut, 673601, Kerala, India.
authors: Linet
authors: L
authors: Rose J
authors: B V R
authors: BV
authors: Tata
authors: V K
authors: VK
authors: Aswal
authors: P A
authors: PA
authors: Hassan
authors: Yeshayahu
authors: Y
authors: Talmon
authors: Lisa
authors: L
authors: Sreejith
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