Stimuli-responsive Materials Based On Malachite Green Derivatives

In recent years, the stimuli-responsive materials attracted more and more interests of peoples, as its physical and chemical properties can be changed by external stimuli. By introducing stimuli-responsive material into supramolecular system, people can realize the control of structure and properties of supramolecular aggregates under external stimuli.In this thesis, two kinds of UV-responsive poly(ethylene glycol) terminated malachite green derivative (PEGn-MG-CN) are designed and synthesized. The UV-responsive amphiphile with both a hydrophobic malachite green group and a hydrophilic PEG group can self-organize into vesicles in water. Upon UV irradiation, the photochromic moiety can be ionized to its corresponding cation, leading to the disassembly of these vesicles. In addition, the cation can thermally recover its electrically neutral form, and the disassembled species can form vesicles reversibly on the basis of a thermal reverse reaction.Besides the amphiphilic molecules, the stimuli-responsive group can be introduced into the surface functionalized molecules. In this thesis, a kind of malachite green derivative with a thiol group (CN-MG-SH) is designed and synthesized. By combination of rough surface and chemical modification of pH/UV-responsive molecule, a kind of novel pH/UV-responsive material is fabricated. Such surface is nearly superhydrophobic at high pH, and is superhydrophilic at low pH.Furthermore, the stimuli-responsive group can be introduced into the surface-active molecules. In this thesis, a kind of UV-responsive polymer with malachite green group (poly-MG-AAm) is designed and synthesized. The photo-responsive polymer with the hydrophobic malachite green group can be used for the formation of an oil-in-water emulsion. However, upon UV irradiation, the photochromic malachite green group could be ionized to its corresponding cation, leading to the conformation change of polymer and further facile reversible UV-controlled and fast transition from emulsion to gel.By the introduction of stimuli-responsive material into supramolecular system, in this thesis, several novel stimuli-responsive materials in solution, on surface, and as gel is fabricated and studied. It is anticipated greatly that this line of research may provide new insights into the mechanism behind stimuli-responsive materials, facilitating the design of new stimuli-responsive materials with designed functions.