The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 31, 1978
Filed:
Feb. 04, 1976
Artur Stoy, Prague, CS;
Renata Urbanova, Prague, CS;
Ceskoslovenska akademie ved, Prague, CS;
Abstract
A method of preparing cross-linked hydrogels in the form of shaped articles, insoluble in any solvent but swellable in water and in aqueous liquids, is provided. The method comprises polymerizing acrylonitrile alone or with a minor amount up to 15% by weight of monoethylenically unsaturated monomers copolymerizable with acrylonitrile under conditions of radical polymerization in concentrated, i.e. 50 to 72%, nitric acid in the absence of any added chain-transfer and cross-linking agents, said monomer or monomers being used in concentrations making possible cross-linking by chain transfer onto the monomer, i.e. in concentrations ranging from 15 to 50%, preferably from 25 to 40% by weight, at temperatures ranging from 0.degree. to 50.degree. C, preferably from 5.degree. to 20.degree. C. The polymerization is carried out in a mold. The lyogel thus obtained is then kept within the same temperature range until the desired swelling capacity in water is reached, and the nitric acid is removed by washing the casting in water or in aqueous liquids.