Comparison to Dielectric Properties of LB Films for Length of Methylene Group

메틸렌기의 길이에 따른 LB막의 유전 특성 비교

We have investigated the dielectric characteristics of palmitic acid(PA), stearic acid (SA) and arachidic acid(AA) Langmuir-Blodgett(LB) films because these fatty acid systems have a same hydrophilic group and a different hydrophobic one (alkyl chain length). In this work. fatty acid systems were used as LB films and the status of the deposited films was confirmed by evaluating the transfer ratio. the UV absorption and the capacitance. Also, the dielectric characteristics such as the frequency-capacitance characteristics and the dielectric dispersion and absorption characteristics of PA, SA and AA through-plane were measured. The relative dielectric constants of PA, SA and AA LB films were about $2.6\sim4.6$, $2.4\sim4.1$ and $2.2\sim3.8$, respectively. That is, the relative dielectric constants were decreased in proportion to the chain length of methylene group. And, the dielectric dispersion and absorption of each fatty acid LB films have arisen from spontaneous polarization of dipole polarization in the range of $10^4\sim10^5[Hz]$.