title: Mixed solutions of an associating polymer with a cleavable surfactant.
abstract: Mixtures of hydrophobically modified hydroxyethyl cellulose (HMHEC) and alkali-sensitive cleavable betaine ester surfactants have been studied by viscometry, 1H NMR, absorbance measurements, and birefringence determinations. Before the hydrolysis, the surfactants behaved as conventional nondegradable surfactants in terms of the effect on the viscosity of increasing surfactant concentration. As the surfactants were hydrolyzed, systems with time-dependent viscosity were obtained. The viscosity either decreased monotonically or went through a maximum as a function of time, depending on the initial surfactant concentration. Different surfactant chain lengths gave rise to different viscosity profiles. The rate of hydrolysis, and thus the time-dependency of the surfactant concentration, could be controlled by changing the pH of the solution.
authors.affiliation: Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Karlberg
authors.forename: Maria
authors.initials: M
authors.lastname: Stjerndahl
authors.forename: Dan
authors.initials: D
authors.lastname: Lundberg
authors.forename: Lennart
authors.initials: L
authors.lastname: Piculell