The odd-even effect of the alkyl chain length of rubbed polyimide Langmuir-Blodgett (LB) films on the extrapolation length of 5CB has been successfully evaluated by measuring polar anchoring strength. The extrapolation length of 5CB for rubbed PI-LB films with even numbers is small compared with odd numbers for alkyl chain lengths of greater than 7 carbons. The extrapolation length of 5CB on rubbed PI-LB films with odd numbers increases gradually as the temperature increases but tends to diverge near the clearing temperature (Tc=35.3°C). The extrapolation length diverges because of rapidly decreasing surface order near Tc. It is suggested that the polar anchoring strength on rubbed PI-LB films with an even number is strong because of relatively high surface ordering caused by more crystalline surfaces. Finally, it is concluded that the odd-even effects of the polar anchoring strength in NLCs are strongly related to the character of the polymer and observed clearly for long alkyl chain lengths.
|Number of pages||1|
|Journal||Applied Physics Letters|
|Publication status||Published - 1995 Dec 1|
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)