Micellar shape transition under dilute salt-free conditions: promotion and self-fluorescence monitoring of stimuli-responsive viscoelasticity by 1- and 2-naphthols.
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.
Saha
Swapan K
SK
Department of Chemistry, University of North Bengal, Darjeeling 734 013, India. ssahanbu@hotmail.com
Jha
Mrinmoy
M
Ali
Moazzam
M
Chakraborty
Amitabha
A
Bit
Goutam
G
Das
Susanta K
SK
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
D002593:Cetrimonium Compounds; D008823:Micelles; D009284:Naphthols; C029350:1-naphthol; D002594:Cetylpyridinium; C028405:2-naphthol; D000077286:Cetrimonium