Mitsuyoshi Oshima

Determination of substituent distribution in cellulose ethers by 13C- and 1H-N.M.R. studies of their acetylated derivatives: O-(2-hydroxypropyl)cellulose

Abstract Structural characteristics of O-(2-hydroxypropyl)cellulose samples, namely the molar substitution (mol. subst.), the total degree of substitution (d.s.), and the individual degree of substitution of hydroxyl groups on the glucose residues for a wide mol. subst. range of samples were determined after peracetylation by 1H- and 13C-n.m.r. analyses. The mol. subst. value was determined by comparing the acetyl methyl proton signal with that of the 2-hydroxypropyl methyl group. The acetyl carbonyl carbon signal of acetylated O-(2-hydroxypropyl)cellulose samples was found to split into a quadruplet in Me2SO at 100°, reflecting the position of the substituent (2, 3, and 6) on the glucose residue and of the (oligo-)propylene oxide substituent end-group, and allowing determination of the substituent distribution as well as the total degree of substitution in a series of O-(2-hydroxypropyl)cellulose samples.

Determination of substituent distribution in cellulose ethers by means of a 13C nuclear magnetic resonance study on their acetylated derivatives: 3. Hydroxyethylcellulose

Abstract The distribution of substituent, i.e. oligo(ethylene oxide) groups, in hydroxyethylcelluloses having various values of molar substitution was determined by means of 13 C nuclear magnetic resonance after the acetylation of hydroxyl groups both at the unsubstituted position in the anhydroglucose unit and at the substituent end position of the parent hydroxyethylcellulose. The acetyl carbonyl signal of the acetylated hydroxyethylcellulose samples was found to split into a triplet in DMSO-d 6 at 100°C corresponding to the positions of acetyl groups (2, 3 or 6 overlapped with the substituent end) on the anhydroglucose unit. While in CDCl 3 at 40°C, the acetyl carbonyl signal for the substituent end position was observed to be separated from those on the anhydroglucose unit. By combining these results, the distribution of the substituent groups was determined for a series of hydroxyethylcellulose samples of a wide range of molar substitution values.

Hydrogen plasma etching method for depth analysis by x‐ray photoelectron spectroscopy

An etching device using a hydrogen plasma has been developed for x-ray photoelectron spectroscopy (XPS) depth profile analysis of organic compounds. The effect of the hydrogen plasma discharge was investigated using a photoresist film containing benzene rings, C– O bonds and C– F bonds formed on an Si(100) wafer. The condenser-type discharge tube employed is composed of electrodes, an etch tunnel (shield tube) and a quartz glass tube. Both the electrodes and etch tunnel have many holes. Experimental results show that the etching rate of the photoresist film is 26.7 nm min−1 at an r.f. power of 200 W, a gas flow rate of 6.0 cc min−1 and a hydrogen gas pressure of 26.6 Pa. This rate is higher than that achieved by the use of a conventional high-speed etching ion gun. It is observed that the etched surface is flatter than that obtained by parallel plate electrodes and an Ar ion beam. The amounts of C, O and F after hydrogen plasma etching were not remarkably different from those before etching, and the shape of the C 1s spectrum did not show any change, indicating no change in chemical bonding. The results show that hydrogen plasma etching is very effective for depth profile analysis of organic polymers by XPS. Copyright