A Study on Wet Dispersing and Grinding, Surface Modified and Synthesis of Nano-sized Particles by Polymeric Dispersant
|關鍵字:||高分子分散劑;濕式分散研磨;奈米氧化鐵;奈米氧化鋅;微乳液;polymeric dispersant;wet grinding and dispersing;nano-magnetite;nano-ZnO;microemulsion|
|摘要:||高分子分散劑，具有一錨接基（anchoring group）與一樹脂相容鏈（binder compatible chain），可應用於奈米粒子之濕式分散與界面改質。本研究實驗結果證實，利用此分散劑亦可形成一微乳液系統，並用以合成奈米粒子。
Polymeric dispersants that comprise of an anchoring group and a binder-compatible chain, exhibiting steric hindrance, can be used in the wet grinding, dispersing and surface modification of nano-sized particles. Polymeric dispersant can also form a microemulsion system and nano-sized particles then synthesized. This work studies the dispersion of nano-sized ZnO in water. Wet dispersion with an appropriate amount of dispersant yields a good suspension with concentrated fill with a high solid content （30wt%）. The particle size distribution is given by D(90)=127nm and the suspension herein has remained stable for at least three years. Nano-sized magnetite particles were synthesized from a low-concentration solution of dispersant, which was identified as a microemulsion system by evaluating the surface tension and particle size distribution, indicating that the magnetite nanoparticles not only had an isolated suspension state and exhibited superparamagnetic behavior, but also achieved surface modification. Surface modification enables an anti-UV coating to be formed by the direct addition of PU resin. The magnetite nanoparticles can also be the immuno-magnetic beads if coated with COOH functional groups, becoming ELISA（enzyme-linked immunoassay）carriers. The sensitivity in Hp antibody detection is similar to that of expensive commercially available immuno-magnetic beads, called Dynabeads M450. Furthermore, this low-concentration dispersant solution can be used to prepare stable colloidal nano-sized silver. The antibacterial property of nano-sized ZnO and silver was evaluated. Antiseptic was made by mixing a suitable amount with PU and these two colloids. The rate of reduction of bacteria by this antiseptic was excellent, because of the good suspension of these nano-sized particles, resulting in a large reactive surface area. The superhydrophilic characteristic of nano-TiO2 was also investigated. Wet dispersion yielded a good suspension of TiO2, which coated the PET film. Its transmittance in the visible region was high and it exhibited superhydrophilicity （with a contact angle of 3 degree） because of the quality of the suspension. In summary, a dispersant can’t be used only to obtain a good suspension of nanoparticles（top down） but also to prepare nanometer- scale particles（bottom up）.
|Appears in Collections:||Thesis|
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