Modification of the structure of cellulose triacetate films in the course of solvent vapor sorption

Abstract

The production of fi lms used as materials for package, fi lters, water treatment membranes, electrical insulation, photography, and motion pictures is a promising application fi eld of cellulose acetates (CAs) prepared from a renewable raw material. Because of large-scale practical use and availability, cellulose derivatives still attract much researchers' attention, since many problems associated with their complicated structural organization remain to be solved. The physicomechanical and ecological properties of materials based on cellulose esters are largely determined by the initial structure of the polymeric material, by its changes under the infl uence of solvents, and by the nature of solvents used for manufacturing the material. Studies of the behavior of CAs in various solvents are also of particular interest today, because cellulose esters characterized by increased chain rigidity tend to ordering and formation of liquid crystal (LC) state in solutions and melts, and also in the presence of organic solvent vapors [1,2]. Hydrogen bonds and donor-acceptor interactions play a signifi cant role in the formation of the anisotropic state of polymer systems and in structural transformations on the molecular and supramolecular levels [3,4]. One of the most sensitive methods for analysis of the structure of macromolecules and intermolecular interactions caused by hydrogen bonds is Fourier IR spectroscopy.This method was used previously [4] for studying the LC formation in cellulose diacetate fi lms in nitromethane and dimethylsulfoxide vapors.This work was aimed at studying intra-and intermolecular interactions in cellulose triacetate fi lms in the course of sorption of vapors of solvents differing in the chemical nature and at evaluating the structure of the polymeric fi lm material. EXPERIMENTALExperiments were performed with cellulose triacetate (CTA) fi lms prepared from a 1.5% solution of CTA in methylene chloride. Films were prepared from cellulose acetate produced in Russia by heterogeneous acetylation and saponifi cation, viscosity-average molecular mass М η = 7.3 × 10 4 . The content of acetate groups, according to the certifi cate data, was 60.5%. Films were prepared in Petri dishes. The solvent was evaporated at room temperature in an air thermostat for 24 h and then in a vacuum box to constant weight without heating. The fi lm thickness was 50-80 μm.As solvents we used dimethylsulfoxide (DMSO, aprotic strongly donor polar solvent, donor number DN SbCl 5 = 28.9, dipole moment μ = 3.96 D [5]), nitromethane (NM, Abstract-Intermolecular interaction and structure of cellulose triacetate fi lms in the course of sorption of dimethylsulfoxide, nitromethane, and tetrachloroethane vapors were studied by Fourier IR spectroscopy, X-ray diffraction analysis, and polarization microscopy. Quantitative ratio of different types of intra-and intermolecular hydrogen bonds in polymer fi lms was estimated. Changes in the structure of cellulose triacetate fi lms in the course of solvent vapor sorption were discussed from...

Sorption of methanol, dimethyl carbonate, methyl acetate, and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis

“…In order to characterize the used CTA, the XRD (Cu‐Kα) pattern was measured; good agreement with the literature patterns was found. By fitting the pseudo‐Voigt functions to the XRD peaks, the pattern revealed four overlapping peaks having maxima of 2 θ at 8.6, 12.4, 17.0, and 21.4° (Fig.…”