The spreading of cellulose derivatives

Abstract

The spreading of cellulose derivatives at the air-water interface has been examined and it has been confirmed that, whereas ethyl cellulose spreads readily and almost completely on water, cellulose acetate and nitrate spread very imperfectly. Limited increases in area per glucose unit for the acetate were obtained by removal of incompletely dispersed aggregates, by spreading from dilute solution, by varying the solvent and by use of NaOH, HCl, or salts in the substrate. On solutions of urea and guanidine hydrochloride (G. HCI), ethyl cellulose gives a slightly increased area per glucose unit, but cellulose acetate and nitrate give areas up to 80 % and 190 % greater than on water. With increasing acetyl

Monomolecular film properties of cellulose and amylose triacetates at the air‐water interface

“…The limiting areas for the ATA and CTA films were reproducible to within k 1.0 A2/glucose unit. Variations in concentration and solvent did not alter the limiting areas by more than however, the compressibilities for CTA are twice as high as those calculated from the data of Borgin and Johnson[4]. The limiting areas for ATA correspond with those published by Katz and Samwel[lo].…”

“…It has been reported [4, 51 that the spreading of CTA is greatly improved by substrates containing high concentrations of urea. The proposed mechanism for improvement of spreading was the disruption of gelated areas stabilized by intermolecular hydrogen bonding [4]. In the present work, however, it was found that when the urea was thoroughly free of surface active impurities, only a slight expansion of approximately 5 A2 occurred on the 3.5 M urea substrate.…”

Preparation, characterization and applications of ultrathin cellulose acetate Langmuir–Blodgett films

“…Langmuir monolayers of various cellulose esters and ethers (mainly with different alkyl side chains) have been extensively studied at the air-water interface. [14][15][16][17]21,23,24 Moreover, the structure and properties of LB films of CA derivatives transferred onto different supports have been studied. [18][19][20]22,25,[28][29][30] However, we are not aware of any report on the properties of CA LB films.…”

“…This observation was attributed to the incomplete spreading of cellulose triacetate on the surface of water, though suggesting that upon compression cellulose triacetate molecules might be somewhat tilted with respect to the water surface, thus giving a smaller projected area. Borgin and Johnson 16 further studied the spreading of cellulose derivatives, concluding that the repeating glucose units were located parallel to the water surface. The possibility that cellulose triacetate could be fully spread and that the glucose units were oriented at an angle with the water surface, had been suggested later by Hittmeier et al 17 They studied the changes in molecular organization and intermolecular interactions in cellulose triacetate LB films following compression.…”

Monolayers of Cellulose Ethers at the Air−Water Interface

“…Monolayers of ethyl cellulose, on the other hand, were found to have limiting areas which agree well with the theoretical ring size. 8 More recently, monolayers of a series of long chain cellulose esters have been investigated. 9,10 In the case of cellulose tridodecanoate, satisfactory multilayers could be prepared, but only by the horizontal lifting method and at surface pressures within the condensed phase.…”