Hierarchical Assembly Of Amphiphilic Copolymer And Application

Currently, the research on self-assembly of the amphiphilic block/random copolymers has obtained a lot of remarkable achievements. However, the applications of self-assembled micelles focus on the design and control of special micelle structures which require multi-step experiments, restrict reaction conditions, and thus limit the utilization. How to open the next door of self-assembly micelles application has been the key research of the relevant field. Recently, hierarchical assembly of different kinds of inorganic or organic micro/nanoparticles provides researchers with new ideas and models. Not only embraced the advantages of first-aggregates, but hierarchical assembly also provided new characters and functions for the resulted hierarchical aggregates.The micro/nanoparticles'ordered arrangements on the surface or in the interface were based on self-assembly or induced-assembly. In this work, the first-aggregates from amphiphilic copolymers self-assembly were used as building blocks. Their behaviors of hierarchical assembly in oil/water interface triggered by interfacial tension, or depositing on the electrode surface induced by applied electric field, were studied respectively, and thus develop new utilizations of the amphiphilic copolymers'hierarchical assembly in emulsification and the field of sensorsThe detailed experiments are described as follows:1. Hierarchical assembly and emulsification of P(St-alt-Ma-Dopa)Using toluene as solvent, an alternating copolymer P(St-alt-Man) was prepared by free radical polymerzation which then underwent ammonolysis with dopamine to obtain an amphiphilic alternating copolymer P(St-alt-Man-Dopa). In selective solvent, P(St-alt-Man) and P(St-alt-Ma-Dopa) self-assembled into stable spherical colloid particles. The P(St-alt-Ma-Dopa) colloid particles showed good surface activity, and thus can further assembled in oil/water interface under the introduce of interfacial tension. Hence, in the process of assembly, the P(St-alt-Ma-Dopa) colloid particles can be used as a novel kind of particle emulsifiers--with P(St-alt-Ma-Dopa) solution as water phase and toluene as oil phase, stable Pickering oil-in-water emulsions were produced. The salinity and the pH value of the aqueous dispersion have different influence on the diameter and the zeta potential of P(St-alt-Man-Dopa) colloid particles. The hydrophilicity of the P(St-alt-Man-Dopa) colloid particles was determined by fluorescence technique using pyrene as probe, and the result showed that the hydrophilicity increased with the increase of pH and decreased slightly with the increase of salinity. The influences by salinity and pH value went on impact the further self-assembly and arrangement of these colloid particles on the oil/water interface, and their emulsification using as Pickering emulsifiers.2. Assembly of MIPMs induced by electric field and its application in MIP sensorsA photo-crosslinkable amphiphilic random copolymer was sythesised from acrylate monomers and styrene. After being acidified with lactic acid, this copolymer was self-assembled into molecularly imprinted polymeric micelles (MIPMs) in the selective solvent butoxyethanol/water with the attendance of template molecule glucose. The morphology and size of the MIPMs were measured by Dynamic Laser Scattering (DLS) and Transmission Electron Microscopy (TEM). Under the introduce of negative electric field, MIPMs swam to working electrode, deposited and ultimately transformed into a film on the electrode surface. The whole process was so called the electric field induced hierarchical assembly of amphiphilic copolymer. The mechanism of electrodeposition was primarily deduced by analyzing the results of Zeta potential. The structure of the resulted MIP film was locked by UV crosslinking. After extracting the template molecule glucose, the electrode became the MIP sensor and has good selectivity and response to glucose. The detections showed that the MIP sensor has linear response ranged from 0.2 mM to 8 mM, with a detection limit of 0.05 mM and an upper limit of 10 mM. Thanks to photo-crosslink of the copolymer which locked the recognition cavities in the MIP film, the MIP sensors show good stability and reproducibility.To sum up, this work explored the advantages of amphiphilic copolymer hierarchical assembly, and provided inspirations for the applications of self-assembly techniques.