Showing papers on "Self-healing hydrogels published in 1970"

Acetalated cross-linked polyvinyl alcohol hydrogels

Abstract: AN ACETALATED CROSS-LINKED HYDROGEL CAPABLE OF IMBIBING WATER AND MICROMOLECULAR WATER SOLUTES AND EXCLUDING MACROMOLECULAR WATER SOLUTES BY THE PROCESS OF SWELLING UPON COOLING PREPARED BY REACTING A POLYMER CONTAINING A PLURALITY OF NEAR NEIGHBOR HYDROXYL GROUPS OR CONTAINING HYDROXYL GROUPS AND ETHER GROUPS, A MONOALDEHYDE AND A DIALDEHYDE, THE REAGENTS BEING INITIALLY IN A STATE OF HOMOGENEOUS AQUEOUS SOLUTION.

Designing of Biodegradable Interpenetrating Polymer Network of Poly(vinyl alcohol-co-acrylic acid)/sodium chloride hydrogel : An Approach to Drug Delivery

Abstract: Interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with polyacrylic acid (PAA), generated insitu, were prepared by without any added crosslinker, using benzoyl peroxide an initiator and sodium chloride (NaCl) as additive. The response of the hydrogels with and without NaCl was observed by studying their swelling behavior, biodegradability and thermal stability. Scanning electron microscopic study revealed that the pores of the prepared IPN were mostly open in presence of NaCl, thus making the hydrogel macroporous. (PVA-co-PAA)/NaCl was found to be more biodegradable than without NaCl. The IPN hydrogel showed comparatively higher swelling at intestinal pH than that of gastric medium and presence of NaCl in the IPN increases the swelling properties in both media. Thermal stability of IPN was affected by copolymerization, due to increasing porosity of the IPN. The prepared nontoxic, hydrophilic IPN hydrogel system holds good for further drug delivery studies in connection to its superswelling and biodegradablity.

Process for manufacture of catalyst material and catalyst material produced thereby

Abstract: 1,213,913. Calcined hydrogels. AMERICAN CYANAMID CO. 11 June, 1968 [10 July, 1967], No. 27686/68. Addition to 1,094,360. Heading C1A. [Also in Division B1] Catalysts are prepared by the addition of an emulsion of a petroleum fraction having a boiling range between 350‹ F. and 900‹ F., to an aqueous slurry of an inorganic oxide hydrogel, followed by shearing the slurry to remove the fluidizing effect of the water, extruding the paste, drying the extrudate and then calcining it at up to 1200‹ F. The formation of the emulsion can be concomitant with the shearing action. It is preferred to use about 1% by weight (of the petroleum fraction) of dispersing agent, preferably a non-ionic detergent, when preparing the emulsion. The solids content of the hydrogel slurry is between 4% w. and 10% w. (of the total slurry). The amount of petroleum fraction used can vary widely but is usually in the range 0-1 to 1-2 parts by weight per part of hydrogel solids. Fines from a previous catalyst preparation may be included in the hydrogel slurry in amount up to 25% by weight of the total calcined solids. Promoters may be present in amounts from 0.1 % to 20-0% w. of the final catalyst composition. The promoters may be included in the hydrogel slurry or be added to the catalyst after calcination. The Specification describes the manufacture of alumina-coated silica hydrogels and the preparation of catalyst from such gels. Hydrogels of silica, alumina, magnesia and zirconia are also referred to.

Coloured contact lenses are produced from hydrogels

Abstract: Coloured contact lenses are produced by enclosing a coloured pattern between at least two layers of a physiologically suitable hydrogel, at least the first layer being transparent on the convex face. The coloured pattern is pref. formed by a coating pigment or insoluble dye in a binder which is compatible with the hydrogel in a swollen condition. The binder pref. consists of a crosslinkable polymer, such as polyethylene monomethacrylate or polyvinyl alcohol. A coloured film may be present in the transparent hydrogel. The construction enables coloured contact lenses to be produced from hydrogels based on hydrophilic polymers. Accurately dimensioned lenses may be readily produced, which are comfortable in use.