Self-assembly of star-shaped poly(2-isopropyl-2-oxazoline) in aqueous solutions

• Published in: Colloid and polymer science Vol. 293; no. 1; pp. 239 - 248
• Main Authors: Amirova, Alina I., Dudkina, Marina M., Tenkovtsev, Andrey V., Filippov, Alexander P.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2015; Springer Nature B.V
• Subjects: Aggregates; Aqueous solutions; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Fluid dynamics; Fluid flow; Food Science; Heating; Hydrodynamics; Nanotechnology and Microengineering; Original Contribution; Physical Chemistry; Polymer Sciences; Self assembly; Soft and Granular Matter; Turbidimetry; Aggregation; Static and dynamic light scattering; Thermosensitive polymer; Lower critical solution temperature; Star-shaped macromolecules
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-014-3402-x

Eight-arm star-shaped poly(2-isopropyl-2-oxazoline) (PiPrOx) with calix[8]arene core ( M  ≈ 20,000 g mol −1 ) was studied by turbidimetry and light scattering in aqueous solutions within concentration c ranging from 0.002 to 0.19 g cm −3 . The lower critical solution temperature (LCST) for PiPrOx is about 10 °C lower than for the linear analog. PiPrOx forms two types of particles at room temperature. The specie responsible for the fast mode is single macromolecules or 2–3 ones joined in aggregate with a hydrodynamic radius of 4.9 nm, irrespective of concentration. On heating, at first, growth of a large aggregate fraction was observed without variation of their hydrodynamic radii R h (s) . Then, R h (s) increased up to 800 nm at c  = 0.002 g cm −3 , while the fast mode disappeared. At all concentrations, the third middle mode with a size ranging from 9 to 40 nm was registered. It was observed in a very narrow temperature interval near the cloud point. The hydrodynamic radii of species and their fraction in solution were monitored as a function of time after the change in temperature.