Study On Self-Assembly Of Anisotropic Polymer Nanorods And Asymmetric Vesicles

Anisotropic nanoparticles are anisotropic in shape or in surface chemistry,which are abundant in nature.Anisotropic nanoparticles are widely applied for their unique physical and chemical properties.For example,they could be applied as find diverse applications as the components of new field-responsive fluids,photonic materials,probes to explore the rheological properties of complex materials,or model systems to mimic anisotropic biological cells and study the self-assembly and packing of anisotropic colloids Polymer solution self-assembly is an effective method to prepare anisotropic nanoparticles.However,compared with the self-assembly of isotropic nanoparticles,the research on the preparation of anisotropic nanoparticles by polymer self-assembly is still limited and there are several challenges including scale up,characterization of anisotropic nanoparticles,and poor controllability of the self-assembly process.In this dissertation,we prepare anisotropic nanoparticles through new polymer self-assembly system or self-assembly method.Meanwhile,new ideas have been provided to solve the challenges in anisotropic nanoparticle research.1.Scalable Preparation of Crystalline Nanorods through Sequential Polymerization-Induced and Crystallization-Driven Self-Assembly of Alternating CopolymersOne dimensional polymer nanorods or worm-like micelles are an important kind of anisotropic nanoparticles,which are usually obtained by self-assembly of block copolymers,and are often prepared in dilute solution,making it difficult for scalable preparation.In this dissertation,1-hexadecylamine（HDA）and 1,3-butadiene diepoxide（BDE）monomers polymerized into alternating copolymers through epoxy-amino click chemistry,which further self-assembled into nanorods during the reaction.The polymer structures were characterized by NMR and GPC.The morphology of the self-assembly was characterized by optical microscopy,polarizing microscope,SEM,and TEM.The self-assembly mechanism of the nanorods were studied by SEM,TEM,DLS and GPC.The results indicated that the formation of nanorods involved one-pot but two-step self-assembly processes:the first step is a polymerization-induced self-assembly（PISA）process,the HDA and BDE monomers polymerized into P（DHB-a-HDA）alternating copolymer through epoxy-amino click chemistry,and meanwhile the polymers self-assembled into small spherical micelles;the second step is a crystallization-driven self-assembly（CDSA）process,the small spherical micelles grew into large spherical micelles,and large spherical micelles aggregated and fused with each other to form nanorods.Thus,we termed it as“sequential polymerization-induced and crystallization-driven self-assembly”（sequential PI/CDSA）.The structure of the nanorods were characterized by DSC,XRD,temperature-variable FTIR and SAXS.The results showed that the nanorods had a precise lamellar structure with an ultrathin lamellar thickness around 4.5 nm.The C₁₆ alkyl chains in the nanorods adopted an all-trans conformation and were in a crystalline state in the lower temperature.They packed in a juxtaposed model with a tilting angle of 30°to form the lamellar structure.In addition,we also investigated the effect of solvents on the morphology of the self-assembly through Micro DSC.2.Asymmetric Vesicles Templated by Double EmulsionSelf-assembly of patchy vesicles or Janus vesicles is an aporia in the field of polymer self-assembly.In this dissertation,three block copolymers of PEO-b-P4VP,PEO-b-PS,and PS-b-P4VP were prepared by ATRP,and PEO-b-P4VP and PEO-b-PS were labeled by Rhodamine B and 1-Pyrenebutanol,respectively.The polymer structures were characterized by NMR and GPC.Then,the three block copolymers co-assembled into vesicles templated by W/O/W double emulsion.Asymmetric vesicles including patchy vesicles and Janus vesicles were formed through polymer phase separation.