Doctoral Dissertations

Date of Award

8-1981

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

James F. Kinstle

Abstract

Many studies have been reported on derivatization of cellulose. Most of these reactions have been conducted under heterogeneous conditions. The objective of the present work was to carry out homogeneous reactions, including grafting, on cellulosics.

The dimethyl sulfoxide-paraformaldehyde (DMSO-PF) solvent system for cellulose (in which methylol cellulose is the solvated species) was considered of potential utility for synthetic reactions on cellulose. Methylol cellulose was prepared by heating cellulose and PF in DMSO, and isolated by precipitation in an acetone-ether mixture. The composition, dissolution process, and synthetic utility of methylol cellulose were examined.

Methylol cellulose containing up to 4.1 oxymethylene units per anhydroglucose unit was isolated. It was essentially impossible to obtain methylol cellulose free of complexed DMSO, and the removal of the latter resulted in concurrent loss of methylol groups. The polymer of moderate to high D̄S˒ of methylol redissolved readily in DMSO, or in solutions of DMF or DMA with ca. 5% LiCl. However, as D̄S˒ was decreased to about 0.2 it was necessary to add ca. 5% LiCl to DMSO in order to dissolve the cellulosic, and polymer of D̄S˒ 0.1 would dissolve only in the DMF-LiCl solvent system.

The dissolution process of methylol cellulose was found to be strongly dependent on hydrogen bonding. FTIR revealed that the extent of hydrogen bonding at 0—5 was reduced as D̄S˒ of methylol was increased. The DMSO present in methylol cellulose appeared to hinder the formation of hydrogen bonds within the cellulosic by the solvent itself becoming associated with the hydroxyl protons. X-ray studies showed that the apparent crystallite size of methylol cellulose, despite the large amount of DMSO trapped in the samples, was not significantly different from that of rayon or hydrolyzed methylol cellulose. Samples of high D̄S˒ of methylol showed a reduction of the 002 plane d-spacing, which increased as the D̄S˒ dropped. This effect was attributed to the association of DMSO with the chains. The role of LiCl in DMSO solutions of methylol cellulose was studied with proton NMR. Deshielding of the anhydroglucose C-H protons indicated there was association of Li+ with the ether oxygens.

Methylol cellulose dissolved in DMF-LiCl could only be partially acetylated with acetyl chloride, but reacted entirely with n-octadecyl and ethyl isocyanates. It was found that there was urethane formation at the methylol groups, and that there was retention of one mole of the latter per mole of anhydroglucose in the urethane derivatives of methylol cellulose.

Sodium cellulose was prepared by reacting methylol cellulose with sodium hydride. This useful intermediate was prepared with D̄S˒ in Na= of 2.09. Graft copolymers of cellulose and acrylonitrile having predictable composition could be prepared in DMSO solutions. Sodium cellulose was also reacted with epichlorohydrin in an attempt to prepare epoxy-substituted cellulosics. Instead, crosslinked cellulosics were obtained.

Deoxyiodo mesyl cellulose was prepared by reacting cellulose with methanesulfonyl chloride to obtain mesyl cellulose, and reacting the latter with sodium iodide. THF solutions of deoxyiodo mesyl cellulose (D̄S˒ iodo 0.76; D̄S˒ mesyl 1.35) were reacted with living oligomers of styrene and isoprene. At 22° living oligostyrene reacted satisfactorily with the cellulosic, while living oligoisoprene caused degradation of the latter. In reactions carried out at 0° and –78° graft copolymers of cellulose and oligostyrene were obtained having nearly predictable composition. With oligoisoprene, the reactions were satisfactory only at –78°.

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