Structure And Properties Of Supramolecular Polymer/inorganic Nanoparticles Ordered Composites

The properties of nanocomposites depend not only on the individual building blocks, but also on the organization and spatial arrangement of individual blocks within the host. Block copolymer, which can microphase separate into a variety of periodically ordered nanostructures, have shown their potential for organizing inorganic nanoparticles in bulk/thin film. Supramolecular block polymers can further provide more versatile routes to control spatial arrangement of the nanoparticles over multiple length scales. Arrangement of nanoparticles to form ordered arrays with single particle precision over macroscopic distances will not only enable a basic understanding of the physical properties of this new family of material, but also pave the way for next-generation nanoparticle-based devices.In this thesis, we systematically investigated the self-assembly behaviors of supermolecular polymers and nanoparticles. The purposes of this thesis include predicting the underlying rules of self-assembled structures with the variation of the content of individual blocks within the host, understanding the origin of the formation of the ordered nanostructures, elucidating of the mechanism for the morphological transitions between different structures, and providing guidelines for design and fabrication of novel nanocomposites.Polystyrene-poly(4-vinyl pyridine)(PS2ok-b-P4VPi7k) and pentadecylphenol (PDP) were dissolved in chloroform to form PS-P4VP(PDP)X (x represents ratio of PDP to P4VP) comb-coil supramolecules. NPs were synthesized and functionalized with a thiol-end PS. Upon addition of PS-coated NPs to the supramolecules, hierarchical structures, where NPs were selectively incorporated in PS cylindrically confined phases within P4VP(PDP)i.o matrices were formed. Isolated wormlike micelles with uniformly dispersed gold NPs along the centerline were obtained by removal of small molecule PDP. This versatile approach allows us to fine tune interparticle distance and micellar morphology by varying the content of nanoparticles and/or hydrogen bonding agent in the supramolecular assemblies. Spatial distribution of NPs in micellar core depends on D/Ro(D denotes the overall diameter of PS-coated Au NPs, Ro is the root-mean-square end-to-end distance of host block of the block copolymer). And the relationship between translational entropy of the particles and polymer conformation entropy were estabilished.The NP loading and the PDP addition effect on the hybrid aggregate morphology with spherical, cylindrical, or nano-sheet morphologies were systematically investigated. The balance between the NP loading and the PDP addition maintains the same micellar morphology while achieves high NP loading. Based on the data above, effect of the amount of PDP and NP loading on the hybrid micellar morphology were summarized in a phase diagram.We describe an effective approach to disperse and orient nanorods (NRs) within cylindrically confined microdomains of block copolymer (BCP)-based supramolecular self-assemblies by tethering two populations of the same homopolymer brushes with different lengths on the surface of the NRs. The mismatch of binary polymer brushes with different lengths on the surface of the NRs was used to effectively improve the dispersion of the NRs within polymer matrix, due to the enhanced wetting of the brushes by surrounding mismatch polymers. Location and orientation of the NRs can be tailored by varying the content of NRs, the aspect ratio of the NRs, or the diameter of the cylindrical nano-objects. UV-visible spectroscopy measurements and finite-difference time-domain (FDTD) calculations confirm that our approach provides a simple yet versatile route to control the optical properties of the hybrid nano-objects via the tunable assembly of the NRs.The hydrophilic gold nanorod grafted with a hydrophobic polymer at both ends was considered as ABA triblock copolymer. We reported on a different approach to fabricate large-area, free-standing2D,3D superlattice through combining phase separation, steric repulsion and long range attractive interaction between nanoparticles. The packing behavior of the metal nanoparticle can be controlled by varying the geometries of nanoparticles or the ligands on the surface of nanoparticles. The self-assembly mechanisms have been discussed.Finally, we introduce a facile way to fabricate hybrid micelles through interfacial instabilities of oil-in-water emulsion droplets containing polystyrene-b-poly(ethylene oxide) and PS-grafted Au nanoparticles. Hybrid micellar morphology can be tuned from vesicles to wormlike micelles and to spherical micelles via varying the concentration of surfactant sodium dodecyl sulfate. In addition, our experimental technique can be extended to encapsulate fullerene(C6o) and polythiophene.These findings will provide an understanding of the nature of the self-assembly of supramolecular polymers and nanoparticles, and help engineers to design ordered nanostructured functional materials and optimize the fabrication process.