• 国内钱逸泰等使用溶剂热合成技术制备 了纳米材料。 • 他们发明了苯热法来代替水热法。 • 可以在相对低的温度和压力下制备出通 常在极端条件下才能制得的、在超高压 下才能存在的亚稳相。 • 在真空中Li3N和GaCl3在苯溶剂中进行热 反应，于280℃制备出30 nm的GaN粒子， 这个温度比传统方法的温度低得多， GaN的产率达到80％。
Advantages
• Cheap for mass production.
• Fast, simple and convenient. • Low-tech (no cleanroom facility needed).
Disadvantages
• No direct control over fabrication. • Can not fabricate very complex structures (as compared to lithography). • Control over crystal orientation is difficult (need microchannels).
A ring of six 27-nm Co particles
TEM and electron holography images of self-assembled Co nanoparticle rings, taken with a Philips CM-300 equipped with a Lorentz lens (300 kV).
Template-Directed Assembly
Using lates
Template-directed colloidal self-assembly
J . Ma t e r . C h em., 2 0 0 4 , 1 4 , 4 5 9 – 4 6 8
Epitaxial self-assembly of block copolymers on lithographically defined nanopatterned substrates
Polymerization
HF etching
Macroporous polymer
Porous Polystyrene
2 m
Double templating
1. Fill voids with liquid precursor, say TiO2..
2. Dissolve the polymer backbone.
Glass slide Glass slide Polymer SiO2 colloidal crystal UV light source Prepolymer Solidified SiO2 colloidal crystal Air spheres 2% HF solution Polymer
2 m
Superlattices
Multiple periodicities. Layers of different sphere sizes.
5 m
type C type B type A
Substrate
macroporous polymer formed from an AB multilayer
§6.2 液相法制备纳米微粒
• 液相法制备纳米微粒是将均相溶液通过各种途 径使溶质和溶剂分离，溶质形成一定形状和大 小的颗粒，得到所需粉末的前驱体，热解后得 到纳米微粒。Solution-based method • 液相法具有设备简单、原料容易获得、纯度高、 均匀性好、化学组成控制准确等优点，主要用 于氧化物系超微粉的制备。 • 液相法包括沉淀法，水解法，水热法，喷雾法， 乳液法，溶胶-凝胶法，其中应用最广的是沉淀 法、溶胶-凝胶法。
Monodisperse TiO2 spheres
Ellipsoidal particles
Macroporous polymer templates can be stretched.
• Stretch temperature. • The particles stretch if heated above glass transition temperature.
---Neeley, dePablo and Stoykovich, Nature, July 24, 2003
Cross-sectional SEM images of PSb-PMMA films a, Lamellae were oriented perpendicularly with no long-range order on unpatterned regions of the surface. b, Lamellae were oriented perpendicularly with epitaxial ordering on surfaces.
§6.3 自组装法 • 自组装是在无人为干涉条件下，组元通 过共价键等作用自发地缔结成热力学上 稳定、结构上确定、性能上特殊的聚集 体的过程。 • 自组装过程一旦开始，将自动进行到某 个预期终点，分子等结构单元将自动排 列成有序的图形，即使是形成复杂的功 能体系也不需要外力的作用。
Fabrication of macroporous polymers
• Manufacturing microelectronics through manipulating block copolymers to form into desirable patterns – e.g. parallel lines. • Lithography used to create patterns in the surface chemistry of a polymer. • The block copolymers on the surface arranged themselves into the underlying pattern without imperfections.