Solution behavior of star polymers with oligo(ethylene glycol) methyl ether methacrylate arms

Star polymers composed of a hyperbranched poly(arylene oxindole) (PArOx) core and arms of different length formed by poly[di(ethylene glycol) methyl ether methacrylate] (PDEGMA) or copolymer poly[di(ethylene glycol) methyl ether methacrylate-ran-oligo(ethylene glycol) methyl ether methacrylate] P(DEGMA-ran-OEGMA) were obtained via atom transfer radical polymerization. The stars obtained were thermoresponsive. The cloud point temperatures (Tcp) depended upon the composition of the arms and the concentration of stars in solution. Comparison of the sizes determined using light scattering techniques in acetone and water below Tcp confirmed that the stars existed in water as isolated macromolecules. The unimolecular structure of the stars below Tcp was proved by AFM and cryo-TEM. Above Tcp, a significant increase in particle size with the concentration was observed. Encapsulation of a hydrophobic dye in stars was studied by UV–VIS and fluorescence spectroscopy. The results indicate that stars obtained are prospective carriers for biomolecules.