Temperature-induced formation and contraction of micelle-like aggregates in aqueous solutions of thermoresponsive short-chain copolymers.
A combination of turbidity, light scattering, and steady shear viscosity experiments has revealed that aqueous solutions of an amphiphilic diblock copolymer or a negatively charged triblock copolymer, both containing poly(N-isopropylacrylamide), can undergo a temperature-induced transition from loose intermicellar clusters to collapsed core-shell nanostructures. Turbidity, light scattering, and viscosity results of these short-chain copolymers disclose transition peaks at intermediate temperatures. At high temperatures, the compact core-shell particles from the diblock copolymer aggregate, whereas no renewed interpolymer association is observed for the triblock copolymer or for the solution of the diblock copolymer with added sodium dodecyl sulfate because the electrostatic repulsive interactions suppress the tendency of forming interpolymer clusters. The temperature-induced building up of intermicellar structures and the formation of large aggregates at high temperature in the solution of the diblock copolymer is significantly reduced under the influence of high shear rates.
Kjøniksen
Anna-Lena
AL
Department of Chemistry, University of Oslo, P. O. Box 1033, Blindern, N-0315 Oslo, Norway.
Zhu
Kaizheng
K
Pamies
Ramón
R
Nyström
Bo
B
D000178:Acrylamides / Q000737:chemistry; D000180:Acrylic Resins; D008823:Micelles; D008956:Models, Chemical; D009391:Nephelometry and Turbidimetry; D011108:Polymers / Q000737:chemistry*; D012542:Scattering, Radiation; D033081:Shear Strength; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012996:Solutions / Q000737:chemistry*; D055672:Static Electricity; D013696:Temperature; D014783:Viscosity; D014867:Water / Q000737:chemistry*
D000178:Acrylamides; D000180:Acrylic Resins; D008823:Micelles; D011108:Polymers; D012996:Solutions; D014867:Water; C052970:poly-N-isopropylacrylamide; D012967:Sodium Dodecyl Sulfate