Abstract
Nematic liquid crystal filled with Aerosil particles, a prospective composite material for optoelectronic application, has been investigated by static light scattering and Photon Correlation Spectroscopy (PCS). The Aerosil particles in filled nematic liquid crystals (FN) form a network structure with LC domains about 2500 angstrom in size with a random distribution of the director orientation of each domain. We found that the properties of 5CB are considerably affected by the network. The N-I phase transition in filled 5CB was found to be smeared out and depressed. PCS experiments show that two new relaxation processes appear in filled 5CB in addition to the director fluctuation process in bulk. The slow relaxation process, with a broad spectrum of relaxation times, is somewhat similar to the slow decay, which is observed in confined nematic liquid crystal. The middle frequency process was assigned to the director fluctuations in the surface layer formed at the particle LC interface. The decay function describing this relaxation process is a stretched exponential (β ≈ 0.7). The temperature dependence of the relaxation times of the middle frequency obeys the Vogel-Fulcher law. Such a temperature dependence, accompanied by a broad spectrum of relaxation times suggests that the dynamics of the director fluctuations near the Aerosil particle-LC interface is glass-like.
| Original language | English |
|---|---|
| Pages (from-to) | 223-228 |
| Number of pages | 6 |
| Journal | Materials Research Society Symposium - Proceedings |
| Volume | 559 |
| DOIs | |
| Publication status | Published - 1999 |
| Externally published | Yes |
| Event | Proceedings of the 1999 MRS Spring Meeting - Symposium onLiquid Crystal Materials and Devices - San Francisco, CA, USA Duration: 5 Apr 1999 → 7 Apr 1999 |