Self-assembly Of Block Copolymer/Janus-like Nanoparticles Mixtures And Patterning

The self-assemby of block copolymers and its applications in fabricating nanoparticles areone of the hottest topics in of polymer science. The self-assemblyed block copolymers permitaccess to various microstructures making them ideal scaffolds for hierarchical control over thesize, particle density, and spatial location of the nanoparticles. Since these nanoparticlespossess the unique and novel feature of properties, they are promising building blocks fordirectional self-assembly of superstructures that are integral to many of the most useful andcomplex features of soft materials. To date, an impressive number of methods have beendeveloped to fabricate Janus nanoparticles with different geometries in large quantity, but theresearch focusing on the properties of Janus nanoparticles are less. In this work, we investigatedthe coassembly of amphiphilic block copolymers with Janus Au-Fe₃O₄and sphere Fe₃O₄inselective solutions and composite films, and preparation arrays of gold-iron oxide compositenanoparticles by using poly（styrene-b-vinylpyridine）（PS-P2VP） block copolymer micelles astemplates.（1） Janus particle Au-Fe₃O₄and sphere Fe₃O₄nanoparticles were synthesized. Thenanoparticles covered by oleic acids or oleylamines molecules were modified with11-Mercaptoundecanoic acid （MUA）. We investigated the self-assembly of amphiphilic blockcopolymers （PS-P2VP） and modification of Au-Fe₃O₄and Fe₃O₄in toluene ortetrahydrofuran. If the contents of Fe₃O₄nanoparticles relative to PS-b-P2VP is1.25wt%, it isfound that the formation of Janus-like aggregates consisting of organic and inorganic phases.（2） Composite films of amphiphilic PS-P2VP copolymers and Au-Fe₃O₄or Fe₃O₄nanoparticles were prepared. Then the composite films were annealed at the temperature150°C for different times. It is found that MUA modified Au-Fe₃O₄nanoparticles areselectively segregated into the cylinders composed of P2VP blocks inpoly（styrene-b-vinylpyridine）（PS-P2VP）. With the increase of the nanoparticles content,structures of phase separated P2VP domains can changed. The obtained results suggest thatannelling time is a key factor, Cmpared to the composite films composed of Fe₃O₄nanoparticles, janus nanoparticles show much more influence on the microphase separation ofblock copolymer.（3） Composite micelles composed of a P2VP/FeCl₃/HAuCl₄core and a PS shell weregenerated by dissolved PS-P2VP block copolymers and inorganic FeCl₃and HAuCl₄·xH₂O inselective solvent toluene. After spin-coating, a monolayer film of the composite micelles onsilicon substrate is obtained. Composite particles were produced by first reducing FeCl₃into Fe using NaBH4solution and then the UV light degradation of the PS-P2VP block copolymer.The obtained nanoparticles were characterized by Atomic Force Microscope（AFM） andEnergy Dispersive Spectrometer （EDS）. The results showed that an array of compositeparticles composed of gold and iron oxide are obtained.