3D Confined Self-assembly And Disassembly Of Diblock Copolymers

Self-assembly and disassembly of block copolymers have gained growing interests due to their important application in preparing polymeric nanomaterials. Except composition, performance of the polymeric nanomaterials and composites also depends on their structure and shape. It is meaningful to design and prepare polymeric nanomaterials with desired structure and shape. Diblock copolymers can self-assemble into aggregates with well-ordered nanostructures, which can be tailored by varying the polymeric composition or external conditions. Selective disassembly of the self-assembled aggregates leads to polymeric nanomaterials with tunable structure and shape.In this thesis, we focus on the3D soft confined self-assembly of diblock copolymer polystyrene-block-poly(4-vinylpyridine)(PS-b-P4VP) by using the emulsion solvent-evaporation method. Nanostructured colloidal particles are achieved through the3D confined self-assembly. These colloidal particles can be further disassembled by selective solvents, resulting in the formation of mesoporous particles, anisotropic nano-objects and their composites. This thesis includes the following four topics:First, a comprehensive study on the3D confined self-assembly of PS-b-P4VP is carried by manipulating PS-b-P4VP composition, solvent selectivity and confined degree. Polymeric colloidal particles with various unique morphologies are thus produced. Especially, formation of colloidal molecules via PS-b-P4VP self-assemble under strong3D confinement is investigated in details. On the other hand, we demonstrate the responsivity of PS-b-P4VP particles by using the3D confined solvent annealing approach. Effect of interface/polymer interaction on transformation of particles is investigated, and reversible transformation of internal structure and shape of the polymeric particles is observed.Second, we demonstrate the3D confined self-assembly and disassembly of PS-b-P4VP(PDP) supramolecular polymer. The supramolecular strategy is an effective route to control the structure of PS-b-P4VP particles. Dependence of self-assembled morphology on the content of PDP is discussed in details. By disassembling the P4VP(PDP) domains of the particles, mesoporous particles or anisotropic nano-objects are obtained. Furthermore, anisotropic polymer/inorganic composite nanomaterials are obtained based on the nano-objects.Third, we developed a route for the formation of Janus nanomaterials by3D confined self-assembly and disassembly of diblock copolymers. Janus nano-discs and Janus nanoparticles are synthesized, respectively. Furthermore, polymer/inorganic composite Janus nanomaterials are prepared. Structure, performance, and hierarchical self-assembly of these Janus nanomaterials are also discussed.Last, the3D confined self-assembly of PS-b-P4VP and polymethyl methacrylate (PMMA) blends are studied. After macro-and micro-phase separation, they form nanostructured Janus colloidal particles. Effect of polymer composition, solvent selectivity, confined degree and interface/polymer interaction on morphology of the particles is systematically investigated. Furthermore, responsivity of these Janus colloidal particles is also studied by using the3D confined solvent annealing.This thesis developed new ways to control the structure of diblock copolymer particles, which are helpful for understanding the3D confined self-assembly behavior. It also provides the foundation for design and preparation of new polymeric particles, mesoporous particles, nanomaterials and their composites, which can be potentially applied in the generation of functional materials and devices.