Polymerization-Induced Hierarchical Electrostatic Self-Assembly Mediated By Amphiphilic Block Copolymer Micelles

Three-dimensional compartmentalization controlled by multiple non-covalent bond interaction is ubiquitous in natural macromolecules.Carrying out research on the mechanism of the compartmentalization of polymers cooperated with multi-interactions in aqueous solution is not only helpful to understand the function of life,but also to develop a new method for the preparation of a class of functional polymer materials,which is a new opportunity for the development of chemistry and materials science.Polyion Complexation(PIC)driven two-step method is used in most of the existing literatures.That is,the amphiphilic block copolymers with polyionic blocks are preassembled to form micelles,which are then combined with the oppositely charged polyions to form compartmentalized structure at nanoscale in low concentration(<1%w/w)aqueous solutions.However,due to some negative factors like the entanglement of polymer chains and the kinetically frozen state,the compartmentalized structures are always imperfect.Contrary to these systems,protein biosynthesis spontaneously forms a nanoscale compartmentalized structure through in-situ assembly of the growing chains with synergistic multi-interactions.The large inner rotation conformation entropy of the growing chains is conducive to the full adjustment of the chain conformation and the formation of the nanoscale compartmentalized structure.Inspired by this assembly process,this thesis presented a new protocol on the basis of the Visible Light Mediated Polymerization-Induced Electrostatic Self-Assembly our group established earlier,that is Polymerization-Induced Hierarchical Electrostatic Self-Assembly Mediated by Amphiphilic Block Copolymer Micelles.Thanks to this new hierarchical PIESA protocol,we successfully synthesized compartmentalized polyion complex micelles and their supracolloidal monolayer nanosheets and nanocages.In this thesis,we established a multicompartmentalized PIC system,which is of great biological significance.We proposed a new protocol,which is Hierarchical PIESA.First,we used visible light initiated RAFT polymerization to synthesize the anionic PAMPS 150 macro-CTA,which has the ability for chain extention.Then we use Photo-PISA to synthesize the preassembled anionic PAMPS150-b-PDAAMp(A150Bp)micelles.To prepare the water-soluble preassembled anionic micelle template with no chain extention activity,we removed the RAFT chain-ends by the oxidation with hydrogen peroxide.Thus,we successfully prepared the preassembled amphiphilic anionic micelles with controllable and uniform size In these micelles,the PDAAM chains were non-ionic hydrophobic core.By changing its degree of polymerization,the size of preassembled anion micelles could be controlledScalable synthesis of ionic-netural multicompartment PIC systems PAMPS 150-b-PDAAM70/PHPMA65-b-PHisAMm(A150B70/C65Dm)has been achieved via visible light-initiated RAFT polymerization of cationic monomer in the presence of preassembled anionic micelles A150B70(Dn=32 nm)in water at 25℃.Based on the great polar difference between the non-ionic hydrophobic dimension and the polyion complex hydrophobic dimension of the polyion micelle,we successfully established a multicompartment structure by taking the non-ionic hydrophobic dimension and the PIC hydrophobic dimension as the core.In this thesis,a multicompartment system with the chain length effect was established,that is,multicompartment micelles were formed by the clustering of preassembled bodies,then monolayer colloidal nanosheets and nanocages were formed by using the multicompartment micelles as assembly units.By studying the kinetics of nanocages(A150B70/C65D200),we unveiled the mechanism of Hierarchical PIESA.It was revealed that the morphology was influenced by strong electrostatic repulsion at low conversion(45-60%)and the coexistence of multicompartment micelles and preassembled anionic micelles,as well as the imperfect supracolloidal nanosheets formed due to the electrostatic repulsion were observed.With the increase of conversion(>92%),the electrostatic repulsion decreases,leading to the formation of a closed nanocage structure.Therefore,this kind of Hierarchical PIESA formed multicompartment PIC micelles and their supracolloidal monolayer nanosheets and nanocages through programmable self-assembly.This new hierarchical PIES A protocol was established by the chain length dependence and the process of PIC under isoelectric point.Finally,to elucidate the effect of anionic micelles on the structural hierarchy,we increased the size by using A150B100(Dn=42 nm)and A150B150(Dn=56 nm)for hierarchical PIESA.Both are larger than the above A150B70 anionic micelles(Dn=32 nm).Prior to agglomeration,A150B100/C65Dx can only evolve into multicompartment micelles(Dn=56 nm)and their colloidal monolayer nanosheet(Dn=58 nm),suggesting that the colloidal nanosheets are made up of multicompartment micelles;A150/B150/C65Dy can only evolve into multicompartment PIC micelles.These values of A150B100/C65Dx are higher than those of A150B70/C65Dm(Dn=49 nm),but lower than those of A150B150/C65Dy(Dn=76 nm).All these demonstrate that smaller-sized anionic micelles resulted in smaller-sized multicompartment PIC micelles and,hence,higher-order structural hierarchy.Therefore,the judicious design of particle size of the preassembled anionic micelles is vitally important for the hierarchical PIESA to access higher-order structural hierarchy of multicompartment PIC systems.In summary,we reported a hierarchical PIESA approach for scalable synthesis of multicompartment PIC systems.The structural hierarchy was achieved via a programmable self-assembly to form multicompartment PIC micelles and their monolayer colloidal nanosheets and nanocages.The judicious design of particle size of the anionic micelles was vitally important for PIESA to access higher order structural hierarchy of multicompartment PIC systems.This work will overcome limitations of imperfect compartmentalization induced by kinetically frozen and entangled polymer chains and low concentrations suffered by the traditional aqueous solution hierarchical assembly,open up an avenue to biologically relevant,yet,otherwise inaccessible multicompartment PIC systems,and extend the scope of visible light-initiated PIESA that was most recently developed by our group.