Interaction between a nonionic surfactant and a hydrophobically modified 2-hydroxyethyl cellulose.
Interaction between the nonionic surfactant Tergitol 15-S-7 and hydrophobically modified 2-hydroxyethyl cellulose (HMHEC) was studied rheologically in a semidilute regime of HMHEC. The low-shear viscosity of HMHEC was increased with addition of surfactant from 25 to 250 ppm, in which the critical micelle concentration of surfactant was near 39 ppm, and then decreased to a value smaller than that of pure HMHEC with further addition of surfactant to 1000 ppm. An interesting shear-induced phenomenon was observed. The steady-state shear measurements show that there exist crossovers between viscosity-shear rate curves of HMHEC solutions with and without surfactant added, whereas it was not observed in the HEC-surfactant systems. Moreover, added Tergitol 15-S-7 reversed the temperature effect on the viscosity of the HMHEC solution. That is, increasing temperature to or near the cloud point raises the viscosity of the HMHEC-surfactant aggregates, in contrast to the viscosity decrease in the pure HMHEC solutions. A possible mechanism based on the necklace model and the clouding phenomenon is conjecturally introduced to explain such phenomena.
Bai
Dongshun
D
Department of Chemical and Biomolecular Engineering, The National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260.
Khin
Cho Cho
CC
Chen
Shing Bor
SB
Tsai
Chih-Chang
CC
Chen
Bing-Hung
BH
D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
D013501:Surface-Active Agents; D002482:Cellulose; C002283:hydroxyethylcellulose