Preparation Of Structural Colored Porous Microspheres Via Interfacial Assembly Of Stimuliresponsive Bottlebrush Block Copolymers

Polymer structural colored pigments have the characteristics of persistent brilliant colors,metallic luster and stimulus responsiveness.Structural colored pigments that are highly safe,environmentally friendly and easy to prepare on a large scale are expected to be an alternative of organic dyes as well as realize new functions.However,there are still some obvious problems needed to be overcome before put into practical use:（1）Self-assembly is the crucial method to prepare structural colored pigments,and structural color is tunable typically relying on changing molecular weights of building blocks.However,in this method,time-consuming chemical synthesis is needed and it is difficult to tune structural color in a continuous and precise way.（2）Common methods for preparing structural colored pigments are difficult to achieve diversified morphologies,which further restricts thoroughly understanding the relationships between structure and optical properties.（3）Most of structural colored pigments do not have dynamic optical properties.Meanwhile,structural colored porous pigments based on polymers can only be stable at a relatively low temperature.Based on the above problems and combined the organized spontaneous emulsification mechanism of bottlebrush block copolymers,a systematic study was carried out in this thesis.（1）Aiming at tuning structural color which is heavily relied on size-varied building blocks,we developed a new strategy for tuning structural color in a continuous and wide way with one polymer via controlling mainchain conformation.Oxidation-responsive amphiphilic bottlebrush block copolymer with ferrocene groups grafted to the hydrophilic block was successfully synthesized.In-situ oxidation of ferrocene groups during structure formation leads to more hydration of the hydrophilic block and more extended mainchain conformation,resulting in larger pore diameters of obtained porous microspheres.Through manipulation of chain elongation by controlling the degree of oxidation of ferrocenes in the hydrophilic block,libraries of structural colored pigments were created,which showed vivid structural colors tunable across the entire visible light range.（2）To enrich the morphology diversity of obtained structural colored pigments,we developed a system of amphiphilic bottlebrush copolymer（BBCP）and silicone oil.Structural colored multiple emulsions could be prepared via organized spontaneous emulsification mechanism.Through varying the BBCP weight percentage,five emulsion structures could be obtained,including branch ordered core-shell multiple emulsions as well as ordered core-shell multiple emulsions.A morphological phase diagram that hinted the structure evolution of obtained emulsions against the increment of BBCP weight percentage was plotted.Transition between different emulsion structures and the relationship between structure of multiple emulsions and photonic properties were uncovered.（3）To achieve structural colored pigments with stimuli-responsiveness and structural colored porous pigments with high-temperature stability,amphiphilic bottlebrush three block copolymers were synthesized.Through organized spontaneous emulsification method and following hydrolysis of poly（tert-butyl acrylate）,structural colored porous microspheres with polyacrylic acid in the inner walls were prepared.The as-formed porous microspheres showed high sensitivity to Arginine(the lowest response concentration reached 10^-3 mol/L)and a relatively fast response（response equilibrium was reached in 4 minutes）.On the other hand,through bio-inspired calcium process,Ca CO₃ was introduced into the inner walls of the porous microspheres,improving the thermal stability of porous microspheres.The thermal stability temperature could reach 200℃.