Constant-Pressure Self-Assembly Langmuir-Blodgett Technique in Dense Nanoparticles Film Formation

• Main Authors: Zheng-jia Liu, 劉政佳
• Other Authors: C. R. Chris Wang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/14865523892423140123

碩士 === 國立中正大學 === 化學所 === 94 === The main theme of my thesis is of the development of a suitable technique in the preparation of a dense film composed of 0D nanoparticles. We have chosen silver nanoparticles synthesized in hexane, with capping (stabilizing) molecules of oleic acid and the average diameters in 5-6 nm, as a model system in our entire studies. The niche of my approach is to combine both conventional Langmuir-Blodgett (LB) technique and the spontaneous self-assembly of hydrophobic nanoparticles at the water-air interface. The method we have been developed called the Constant-Pressure Self-Assembly (CPSA) procedure for fabricating such film. The CPSA comprises of two steps: (i) the conventional LB barrier movement from a dispersed “gas” state to the “transition” state and (ii) self-assembly of nanoparticles at the water/air interface at a constant surface pressure. The second stage of the CPSA process proceeds along with the automatic barriers’ movement to maintain the constant surface pressure. Generally, the reduction of the amount of empty areas on the surface due to the self-assembly leads to the barriers moving towards each other and a decrease of the total surface area. We can then successfully obtain a two-dimensional dense film composed of hydrophobic nanoparticles from such CPSA process, dense monolayer LB film that were pushed by two barriers to compress. The resulting dense monolayer film indicates the interparticle distances are as closed as 2~3 nm which is in accordance with the total length of the capping molecules at the nanoparticle surfaces. I have arranged the content of my thesis in such a way that the readers can get a clear pictures of the CPSA technique in detail, including Chapter 1: the introduction of the LB technique, isotherm, model derivation of surface pressure detection, Chapter 2: the preparation of a suitable silver nanoparticles LB solution and its characterization, Chapter 3: the detail description and discussion of our CPSA technique, and Chapter 4: the conclusion and prospect of this new LB-CPSA technology.