Dynamic Viscoelasticity and Concentration Dependence of Micelle-Gel Transition of Styrene and N-tert-Butylacrylamide Diblock Copolymer Solutions

作者：Sharma Nitin; Kasi Rajeswari M^*

来源：Langmuir, 2010, 26(10): 7418-7420.

DOI：10.1021/la100666t

We present dynamic viscoelastic studies of styrene and N-tert-butylacrylamide block copolymers (S(278)NtBAM(517) and S(93)NtBAM(252)) in I-octanol as a function of copolymer concentration at 15, 25, and 35 C. Dilute solutions of these diblock copolymers in 1-octanol, a selective solvent for N-tert-butylacrylamide units, yield spherical micelles as evidenced by transmission electron microscopy (TEM). Dynamic light scattering (DLS) is used to determine hydrodynamic radius of the micelles as a function of temperature (15, 25, and 35). Dilute solutions of these block copolymers behave as viscoelastic fluids in the low frequency range. At higher concentrations, these copolymer solutions form glass-clear gels. Rheological measurements show that these block copolymer solutions exhibit power-law behavior at the gel point (G'(omega) similar to G ''(omega) similar to omega ''). In this paper, we discuss the formation and properties of critical gel states of S(m)NtBAM(n) in 1-octanol based on (1) concentration dependence of micelle-gel transition, (2) determination of critical state by rheology, and (3) temperature dependence of critical gel concentration and material parameters.

• 出版日期2010-5-18