Study On Intelligent Photo-controllable System Based On Malachite Green Carbinol Base As Photo Base Generators

Photoresponsive polymer materials have been widely studied and applied due to their excellent properties such as safety,cleaning,fixed-point timing control,remote controllability and so on.The common photoresponsive polymer materials are mainly based on the following photosensitive groups: azobenzene,spiropyran,and cinnamaldehyde and triphenyl methane.The preparation of photosensitive polymers is complicated by grafting some photosensitive groups onto polymer chains.In addition,its photosensitive performance is not universal.In this work,a photobasei generators-Malachite Green Carbinol Base(MGCB),a hydroxide ion emitter,is used.Under ultraviolet light,the MGCB can be cleaved into ion pairs,releasing hydroxide ions,thus the p H of the solution is increasing.The factors affecting MGCB performance are explored in this paper in terms of solvent,MGCB concentration,illumination time and intensity.The experiment showed that when the MGCB concentration was 0.5 m M,the illumination intensity was 500 W,the p H of the solution can be increased by 4 units after illumination within the 4 min.And the concentration of hydroxide ions in the solution increased by about 445 times.The amphiphilic block copolymers PDEAEMA-b-PEG-b-PDEAEMA with different hydrophilic ratios were prepared by ATRP polymerization.The p H sensitive nanopaticles,P-NPs and MGCB@P-NPs,were prepared to study the effect of the photobase properties of MGCB on polymer self-assembly at the low polymer concentrations andsol-gel transition at high polymer concentration.The experiments showed that under light control,the emicelle morphology of polymer nanoparticles loaded with MGCB exhibit a model change of "sphere(vesicle)-rod-chain" and the morphology transition can be quickly realized and controlled under light illumination.With the high polymer concentration,MGCB is distributed in the polymer solution.The hydrophobic degree of the polymer increases with the solution p H increasing by illumination,and the chain segments are entangled with each other to realize the sol to the gel.The gel is reversible and the gel-sol changes can be achieved by increasing the temperature.Besides,the concentration of MGCB increases,the better the stability and repeatability of the gel.To further demonstrate the universality of MGCB photobase properties,mesoporous silica nanoparticles grafted with phenylboronic acid and dopamine loaded with MGCB through hydrophobic interactionwere were prepared.The DLS and SEM tests showed thatthe solution p H increased under UV treatment,phenylboronic acid and dopamine formed dynamic borate bonds and then aggregated with each other.Nanoparticles were depolymerized after 60 min of dark treatment.MGCB not only has the photobase property,but also has the light discoloration property.Therefore,gels containing MGCB were prepared by secondary reaction,which produced a step-by-step color change with the illumination time.A variety of composite color gels named Rh B-MGCB@AM-gel were prepared in accordance with rhodamine dye.They are expected to be used in anti-counterfeiting marking and information storage.