Preparation and Characterization of 6-O-(4-stearyloxytrityl)Cellulose acetate Langmuir–Blodgett Films

Abstract

Multilayer films of 2,3-di-O-acetyl-6-O-(4-stearyloxytrityl)cellulose (ASTC) were prepared and investigated. The fairly high surface pressure (p)-area (A) isotherms (36-47 mN/m) suggest that the balky and hydrophobic trityl group contribute to form a condensed monolayer. The cellulose derivative formed a homogeneous monolayer at 10 mN/m. The monolayer on the water surface was transferred successfully at 10 mN/m onto various substrates by modifying the preparation methods, to form Z-type multilayer films. The ultraviolet-visible (UV-Vis) absorbance was independent of the number of layers, indicating that each layer is made of definite number of anhydroglucose unit (AGU). The monolayer thickness determined from atomic force microscope (AFM) and ellipsometry was calculated to be about 1.9 nm, suggesting that the long alkyl chain in the film has a so-called hairy-rod type structure. This is the first paper about the Z-type LB film prepared from cellulose derivatives having long mono-alkyl chain only at 6-O-position.

Preparation and Characterization of Monolayer and Multilayer Langmuir−Blodgett Films of a Series of 6-O-Alkylcelluloses

“…In a previous paper, we made various attempts to prepare high-quality LB films of 6-O-(4-stearyloxtytrityl)cellulose and obtained multilayer Z-type films by the vertical dipping method. 26 Then, we tried to prepare a 6-O-stearylcellulose LB film by applying the improved method at a pressure π ) 10 mN m -1 at 20 °C. The 6-O-stearylcellulose monolayer was also transferred only by the upward stroke onto mica and was not transferred by the downward stroke, indicating that Z-type deposition occurred.…”

“…Preparation of C 18 C LB films was applied to our improved method described in a previous report. 26 The vertical dipping method was used to deposit the surface monolayer onto the substrate. The upward and downward stroke rate is 10 and 7 mm min -1 , respectively.…”

“…24,25 Then, acetates of the obtained 6-O-(4-stearyloxytrityl)cellulose (C 18 TCAc) were found to form fairly uniform and stable Z-type LB films. 26 This indicates that the cellulose derivatives with a monoalkoxytrityl substituent per anhydrous glucose unit (AGU) form LB films successfully. It is presumed that the cohesive force of the bulky and hydrophobic trityl group considerably contributes to forming stable LB film.…”

Preparation and characterization of redox cellulose Langmuir–Blodgett films containing a ferrocene derivative

“…In a previous study,26 we made various attempts to transfer a homogeneous STCAc monolayer by a vertical dipping method, and then multilayers could be prepared with a transfer ratio of unity. Thus, we attempted to prepare an STCFc LB film by the improved method, but trials of deposition failed.…”

“…In a previous article,24, 25 we synthesized a series of novel 4‐alkoxytrityl chlorides with various chain lengths and succeeded in reacting cellulose with novel 4‐alkoxytritylation reagents with a high degree of substitution (DS) and high regioselectivity at the 6‐ O position. Moreover, the cellulose derivative formed a homogeneous monolayer at the air–water interface, and the monolayer was transferred successfully onto a substrate; this indicated that even the cellulose with the 6‐ O ‐mono‐alkyl substituent formed a stable LB film 26…”