The thermo- and potassium-ion-responsive
phase transitions of the star copolymer were investigated by measuring
the turbidity, morphology of aggregation, and hydrodynamic diameter.
The turbidity of the obtained polymer in deionized water with 0, 5,
60, 80, 100, and 160 mM KCl was evaluated using a UV–vis spectrophotometer,
V-630BIO (JASCO Co., Tokyo, Japan), at a wavelength of 420 nm. NaCl
was added to the measurement solution to maintain a total ion concentration
of 160 mM. The phase transition behavior was investigated in the range
of 20–50 °C at an increasing rate of 1 °C/min. The
morphology of the star copolymer in the aggregated state in the presence
of 160 mM NaCl was observed by two-photon confocal laser scanning
microscopy (LSM510 META NLO, Carl Zeiss Co. Ltd., Jena, Germany).
The hydrodynamic diameter of the star copolymer in deionized water
with 160 mM KCl or 160 mM NaCl was evaluated using a dynamic light
scattering (DLS) LB-500 (HORIBA Ltd., Kyoto, Japan) with a diode laser
(wavelength = 650 nm) at 20 and 40 °C.
phase transitions of the star copolymer were investigated by measuring
the turbidity, morphology of aggregation, and hydrodynamic diameter.
The turbidity of the obtained polymer in deionized water with 0, 5,
60, 80, 100, and 160 mM KCl was evaluated using a UV–vis spectrophotometer,
V-630BIO (JASCO Co., Tokyo, Japan), at a wavelength of 420 nm. NaCl
was added to the measurement solution to maintain a total ion concentration
of 160 mM. The phase transition behavior was investigated in the range
of 20–50 °C at an increasing rate of 1 °C/min. The
morphology of the star copolymer in the aggregated state in the presence
of 160 mM NaCl was observed by two-photon confocal laser scanning
microscopy (LSM510 META NLO, Carl Zeiss Co. Ltd., Jena, Germany).
The hydrodynamic diameter of the star copolymer in deionized water
with 160 mM KCl or 160 mM NaCl was evaluated using a dynamic light
scattering (DLS) LB-500 (HORIBA Ltd., Kyoto, Japan) with a diode laser
(wavelength = 650 nm) at 20 and 40 °C.