title: Micellar shape transition under dilute salt-free conditions: promotion and self-fluorescence monitoring of stimuli-responsive viscoelasticity by 1- and 2-naphthols.
abstract: Effect of 1 and 2-naphthols on the shape transition of cetyl trimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) micelles are studied. Stimuli-responsive viscoelastic gels of long wormlike micelles are formed at low surfactant concentrations in the presence of neutral naphthols, where H-bonding plays a key role in micellar shape transition in the absence of any charge screening. Micelle-embedded naphthols also act as novel self-fluorescence probes for monitoring viscoelasticity of the system as a function of applied shear. 1H NMR study shows that the solubilization sites of naphthols in the micelle are located near the surface. While UV absorption and Fourier transform infrared studies confirm the presence of intermolecular H-bonds in micelle embedded naphthols, transmission electron micrographs of vacuum-dried samples at room temperature demonstrate the transition in shape from sphere to rodlike micelles.
authors: Department of Chemistry, University of North Bengal, Darjeeling 734 013, India. ssahanbu@hotmail.com
authors: Swapan K
authors: SK
authors: Saha
authors: Mrinmoy
authors: M
authors: Jha
authors: Moazzam
authors: M
authors: Ali
authors: Amitabha
authors: A
authors: Chakraborty
authors: Goutam
authors: G
authors: Bit
authors: Susanta K
authors: SK
authors: Das
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D002594:Cetylpyridinium / Q000737:chemistry*; D004548:Elasticity; D005453:Fluorescence; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008823:Micelles; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009284:Naphthols / Q000737:chemistry*; D010316:Particle Size; D044367:Phase Transition; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D014783:Viscosity
chemical_list: D002593:Cetrimonium Compounds; D008823:Micelles; D009284:Naphthols; C029350:1-naphthol; D002594:Cetylpyridinium; C028405:2-naphthol; D000077286:Cetrimonium