Effects of Substrate and Experimental Conditions on the Fabrication of Well-Ordered Silica Particulate Langmuir–blodgett Films

Abstract

The dependence of particulate LangmuirÀBlodgett (LB) monolayer quality on the surface nature of the substrate was investigated by pretreating the substrates with di®erent methods, and the optimal withdrawal speed was determined by detecting the quality of particulate monolayers deposited at di®erent withdrawal speeds. Furthermore, the e®ects of stearic acid (SA) concentration on the quality of particulate monolayers were discussed. Results indicated that surface amination would favor the transfer of the°oating particulate monolayer from the interface to the substrate, which would be attributed to the formation of chemical bonds between the ÀNH 2 groups on the substrate surface and the functional groups of ÀCOOH and SiÀOH groups on surfaces of particles°oating at the interface. And the withdrawal speed of 1 mm Á min À1 was appropriate for the fabrication of high-quality particulate LB monolayer because low withdrawal speed can o®er su±cient time to form chemical bonds and expel the subphase from the substrate. Additionally, SEM images illustrated that the SA concentration of 0:40 mg Á mL À1 was suitable for the fabrication of well-ordered particulate LB monolayers composed by the particles of 380 nm.

Behavior of Methylene Blue With Arachidic Acid in the Restricted Geometry of Langmuir–blodgett Film

“…The study of LM is based on the alignment of amphiphilic molecules at the air-water interface in a monomolecular layer, where the hydrophilic groups anchor onto the aqueous subphase and the hydrophobic groups point towards the air [1]. A lot of works on LM were performed using long chain fatty acid [2][3]. Although materials suitable for LM formation are the amphiphilie, several studies indicate that some water soluble dye molecules can also form stable monolayers when a suitable matrix is used as supporting medium [4][5].…”