Photorheological Effects in Aqueous Micellar Tetramethylammoniumhydrogen-2-dodecyl Malonate via Photodimerization of Acridizinium Bromide.
Aqueous solutions of tetramethylammoniumhydrogen-2-dodecyl malonate (TMHM) were investigated rheologically in the absence and presence of monomeric and photodimerized acridizinium bromide as solubilizates. Upon constant shearing a viscosity increase (accompanied by viscoelasticity) was observed in a certain range of TMHM concentration after an induction period. This indicates the formation of shear induced structures. Viscoelasticity was characterized via stress relaxation experiments revealing a single relaxation process with time constants of 0.2-0.3 s mostly. At certain shear rates a temporal oscillation of viscosity was observed. In the presence of acridizinium bromide the elasticity was reduced and the TMHM concentration range of viscoelastic flow was narrowed while relaxation time constants remained constant. Photodimerization of acridizinium bromide (performed in situ) reverted the effects induced by the monomers. Copyright 1999 Academic Press.
Lehnberger
C
Institut für Physikalische Chemie und Elektrochemie, Technische Universität Dresden, Dresden, D-01062, Germany
Wolff
T