Preparation Of Janus Nanoparticles By Using Amphiphilic Block Copolymers And Their Mixtures As Templates

In this thesis, the preparation methods of asymmetric nanoparticles by using theself-assembled structures of block copolymers or their blends were studied. First, weinvestigated the self-assembled structures of block copolymerpolystyrene-b-poly2-vinylpyridine (PS-b-P2VP) in toluene after addition of NaOHsolution, the factors influencing the formation of the asymmetry nanoparticles, as wellas the morphology and size changes. Second, the self-assembled structure of blockcopolymer polystyrene-block-poly(2-vinylpyridine)(PS-b-P2VP)、poly(2-vinylpyridine)-block-poly(ethyleneoxide)(P2VP-b-PEO) with inorganicHAuCl4was used to prepare gold nanoparticles. And the morphological anddimensional changes of compound micelles constituted of block copolymers andinorganic components were also studied. Third, the mixture of the diblock copolymers,PEO-b-PMMA and P2VP-b-PMMA, were used to prepare Janus nanoparticles. theinfluences of the preparation conditions on the formation of Janus nanoparticles werestudied and the formation mechanism of Janus nanoparticle was simply discussed.(1) A simple approach to preparation of block copolymer vesicles throughultrasonic treatment of PS-b-P2VP micelles under alkaline conditions is reported.PS-b-P2VP block copolymers form spherical micelles in toluene. If small amount ofNaOH/THF/H2O solution is added to the micelles solution which can regulated thepH of the solution and change the solubility of every block as well as variousinteractions of the system, and ultrasonic, organic-inorganic Janus-like nanoparticlescomposed of the PS-b-P2VP block copolymers and NaOH are generated. Afterremoval of NaOH, block copolymer bicontinuous phase structures are obtained. Ifblock copolymer micelles containing inorganic precursors (such as FeCl3), hybrid vesicles are prepared, which may be useful as biological and chemical sensors ornanostructured templates..(2) Gold nanoparticles (AuNPs) by using the mixture ofpolystyrene-block-poly(2-vinyl pyridine)/poly(2-vinyl pyridine)-block-poly(ethyleneoxide)(PS-b-PVP/PVP-b-PEO) block copolymers (BC) as encapsulating agent wasprepared. The prepared AuNPs were characterized by transmission electronmicroscopy (TEM), UV-vis spectroscopy and contact angle. It is demonstrated thatthe obtained AuNPs are covered with mixed block copolymer shells. The hydrophilicproperty of the AuNPs can be varied by the change of the dispersion medium. Theobtained AuNPs with mixed block copolymer shells are stable in organic solvents.(3)We prepared Janus nanoparticles by using the mixture of block copolymerPEO-b-PMMA and P2VP-b-PMMA. First of all, we mixed equal quality ofPEO-b-PMMA/THF and P2VP-b-PMMA/THF solution. We use the PVP sensitivityto pH，then added aqueous solution with different pH slowly，to change the solubilityof each block and various interaction of the system， until the solution becameivory-white. Afterwards, volatilized the solvent THF.Finally,we found that we can getJanus particles in a certain conditions.