| 학회 |
한국고분자학회 |
| 학술대회 |
2007년 봄 (04/12 ~ 04/13, 제주 ICC) |
| 권호 |
32권 1호 |
| 발표분야 |
액정/LCD용 고분자 재료 |
| 제목 |
Liquid crystalline phases from anisotropic, polymer functionalized nanoparticles |
| 초록 |
It is the aim of this work to realize liquid crystals from anisotropic inorganic materials in organic solvents. To realize liquid crystalline phases it is necessary to combine a high degree of order with a certain mobility of the building blocks. Inorganic nanoparticles have the disadvantage of strong adhesion forces among each other and are therefore not well disperseable. To reduce the aggregation between anisotropic inorganic nanoparticles it is necessary to stabilize them. This is done best with block copolymers consisting of an anchor block for multidental fixation to the nanoparticle and a soluble block. The resulting hard anisotropic particles functionalized with flexible polymer chains resemble the “hairy-rod structure” known from stiff LC-main chain polymers. For the build-up of defined functional polymers controlled radical polymerization is the most suitable polymerization method. It is highly compatible with most functional groups and allows the controlled synthesis of block copolymers. For each nanoparticle it is necessary to use specific anchor groups. For TiO2 nanorods, catecholes are used. One can introduce anchor groups by using reactive ester monomers and after their polymerization it is possible to introduce the anchor groups polymer-analogously. The polymer coated TiO2 nanorods thus prepared can be dissolved easily in organic solvents. Lyotropic LC-phases can be found from dispersions from these anisotropic TiO2 nanorods and can be recognized from the texture typical for nematic phases. In blends of PEG 400 with polymer covered nanorods one can find an isotropic, a nematic and two smectic LC-phases. In experiments with substrates that were drawn out of nanorod dispersions nematic orientations could be found in drawing direction. This proves that LC-ordering can be used to order anisotropic inorganic nanoparticles. Very interesting hybrid systems can be obtained by using hole conducting polymers as soluble block. Thus one can combine the issues of mobility, solubility, conductivity and orientability in TiO2 nanorod hybrid systems. |
| 저자 |
S. Meuer1, R. Zentel2
|
| 소속 |
1Univ. of Mainz, 2Duesbergweg 10-14 |
| 키워드 |
Liquid crystal; nanoparticle; block copolymer; TiO2
|
| E-Mail |
|
