UV-Responsive Polymeric Superamphiphile Based on a Complex of Malachite Green Derivative and a Double Hydrophilic Block Copolymer

We have prepared a UV-responsive polymeric super-amphiphile, formed by a malachite green derivative and the double hydrophilic block copolymer methoxy-poly(ethylene glycol)(114)-block-poly(L-lysine hydrochloride)(200) (PEG-b-PLKC) on the basis of electrostatic interactions. The malachite green derivative undergoes photo-ionization upon UV irradiation, which makes it more hydrophilic, resulting in changes in the self-assembly behavior of the polymeric superamphiphile. For this reason, the polymeric superamphiphile originally self-assembles to form sheetlike aggregates, which disassemble after UV irradiation because of the increased solubility of the malachite green derivative. By use of Nile red as a probe, the polarity of the polymeric superamphiphile solution is confirmed to be increased after UV irradiation by fluorescence spectra, which also explains the disassembly of the polymeric superamphiphile.