Cellulosic-liquid composite materials and process of preparing such materials
AssigneeMoleculon Research Corporation
InventorLarry D. Nichols
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Abstract
Polymer-liquid composite materials, particularly of cellulosic polymers such as cellulose nitrate, are described, which materials are strong, transparent, ultramicroporous materials characterized by a diffusion-supporting liquid phase of about 70% or more liquid within an interpenetrating, form-retentive, solid polymer phase. The materials are prepared by precipitation from a hydrogen-bonding solvent solution by the use of a miscible nonsolvent at temperatures generally below about 45.degree. C.
Claims15
A process of preparing a polymer-liquid composite material, which process comprises:
- a. providing a solvent solution of a cellulosic polymer having electronegative substituents, wherein the cellulosic polymer is selected from the group consisting of cellulose nitrate with a degree of substitution greater than about 2.25, cellulose acetate with a degree of substitution greater than about 2.90, a mixed cellulose nitrate and acetate cellulosic ester with a degree of substitution between about 2.25 and 2.90, and cellulose propionate with a degree of substitution greater than about 2.90, the solvent comprising a hydrogen-bonding solvent;
- b. casting a wet film of the solvent solution;
- c. forming an insoluble film by precipitating the cellulosic polymer in the wet film by contacting the film with a nonsolvent for the polymer, which nonsolvent is miscible with the solvent for the polymer so as to replace the solvent with the nonsolvent at a temperature below about 45.degree. C to provide an essentially transparent, self-supporting, irreversibly shrinkable, ultramicroporous cellulosic polymer film having distinct interpenetrating cellulosic polymer and liquid nonsolvent phases.
The process of claim 8 wherein the nonsolvent is water and the solvent is a hydroxyl or carboxyl-containing organic liquid.
A process for preparing a cellulosic-liquid composite material, which process comprises:
- a. providing a solvent solution of cellulose polymer containing from about 0.5 to 15% cellulose polymer in a nondegrading hydrogen-bonding solvent, the cellulose polymer selected from the group consisting of cellulose nitrate with a degree of substitution greater than about 2.25, cellulose acetate with a degree of substitution greater than about 2.90, a mixed cellulose nitrate and acetate cellulosic ester with a degree of substitution between about 2.25 and 2.90, and cellulose propionate with a degree of substitution greater than about 2.90;
- b. coating the cellulose polymer solution into a wet-film form;
- and
- c. precipitating the cellulose polymer in the wet film by immersing in a nonaqueous nonsolvent for the cellulose polymer, which nonsolvent is miscible with the solvent for the cellulose polymer, so as to replace the solvent with the nonsolvent by such immersion, the precipitation carried out at a temperature below about 40.degree. C to provide a cellulose polymer-liquid composite film material having at least about 70% of the nonsolvent, the material essentially transparent, self-supporting, irreversibly shrinkable, ultramicroporous, with distinct interpenetrating cellulose nitrate and a liquid nonsolvent phase.
Dependencies are inferred from the claim text.