Wettability of fibrous quartz with Langmuir-Blodgett films of arachidic acid and/or cellulose didecanoate

The wettability of quartz with Langmuir-Blodgett (LB) films of arachidic acid (AA) and/or cellulose didecanoate (CDD) was investigated by contact angle measurements, employing the Wilhelmy method. The advancing angles increased considerably with the film deposition, especially for the AA films, whereas the receding angles increased only slightly. A further increase in the advancing angles with time was found after the film deposition. The experimental results are discussed considering the quartz with the LB films to have a heterogeneous surface, i.e. predominantly high-energy surface with fractional low-energy regions. The increment in the advancing contact angle due to film deposition is explained by the increase in the percentage of the low-energy region. The time dependence of the advancing angle after the film deposition is considered to be caused by the increase in the difference in the intrinsic wettability between the low-energy and high-energy regions due to rearrangement of the molecules in the LB films and the migration of the AA molecules towards the air.