Effects of substrate and experimental conditions on the fabrication of well-ordered silica particulate langmuir-blodgett films

The dependence of particulate Langmuir-Blodgett (LB) monolayer quality on the surface nature of the substrate was investigated by pretreating the substrates with different methods, and the optimal withdrawal speed was determined by detecting the quality of particulate monolayers deposited at different withdrawal speeds. Furthermore, the effects of stearic acid (SA) concentration on the quality of particulate monolayers were discussed. Results indicated that surface amination would favor the transfer of the floating particulate monolayer from the interface to the substrate, which would be attributed to the formation of chemical bonds between the-NH₂ groups on the substrate surface and the functional groups of-COOH and Si-OH groups on surfaces of particles floating at the interface. And the withdrawal speed of 1 mm ṡ min^-1 was appropriate for the fabrication of high-quality particulate LB monolayer because low withdrawal speed can offer sufficient time to form chemical bonds and expel the subphase from the substrate. Additionally, SEM images illustrated that the SA concentration of 0.40 mg ṡ mL ^-1 was suitable for the fabrication of well-ordered particulate LB monolayers composed by the particles of 380 nm.