Watching cellulose grow – Kinetic investigations on cellulose thin film formation at the gas–solid interface using a quartz crystal microbalance with dissipation (QCM-D)

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 400; pp. 67 - 72
• Main Authors: Mohan, Tamilselvan, Spirk, Stefan, Kargl, Rupert, Doliška, Aleš, Ehmann, Heike M.A., Köstler, Stefan, Ribitsch, Volker, Stana-Kleinschek, Karin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.04.2012
• Subjects: Cellulose; Cellulose model films; Concentration (composition); Dissipation; Hydrolysis; Interface reaction; Kinetics; Microorganisms; Quartz crystal microbalance; Reaction kinetics; Thin films; Trimethylsilyl cellulose; Vapor phases; Wettability; Trimethylsilyl cellulose; Cellulose model films; Quartz crystal microbalance; Kinetics; Interface reaction
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2012.02.053

[Display omitted] ► The reaction of trimethylsilyl cellulose thin films with HCl vapor is studied. ► QCM-D allows an in situ monitoring of this reaction under ambient atmosphere. ► Rate constants for this reaction have been determined. ► The reaction proceeds via a first fast phase and a second slower phase. ► The formed cellulose films show a layer thickness of 23nm. The conversion of trimethylsilyl cellulose (TMSC) to cellulose films via acid vapor hydrolysis is investigated at the gas solid interface in situ, in real time and under ambient conditions using the QCM-D technique. For this purpose, a permanent flow of gaseous HCl is employed which reacts with TMSC spun on QCM sensors to form cellulose films. The kinetics behind this reaction is elucidated and reveals first order. This desilylation reaction proceeds via a fast first phase (k=3.01×10−3s−1) and a second slower phase (k=6.29×10−5s−1) where less accessible silyl groups are cleaved off. Besides kinetics, film thicknesses have been determined using the QCM method. Moreover, the influence of the acid concentration on the kinetics and layer thickness was studied. A comparison between the materials synthesized in the QCM chamber with those obtained by classical vapor phase hydrolysis does not show any differences in the surface characteristics and composition as proven by X-ray photoelectron spectroscopy, atomic force microscopy, and wettability studies.