Showing papers on "Self-healing hydrogels published in 1974"

Hydrogels and articles made therefrom

Abstract: This invention relates to copolymers and hydrogels formed by copolymerization of a hydrophilic monomer from the group of dihydroxyalkyl acrylates and methacrylates and a substantially water insoluble monomer from the group of alkyl acrylates and methacrylates. The preferred copolymer of the invention is formed from methyl methacrylate and glyceryl methacrylate (2,3-dihydroxypropyl methacrylate). The hydrogels of the invention have unique physical and physiological properties which are particularly useful for the formation of contact lenses, particularly contact lenses having a relatively thin cross-section, though they may also be used for other purposes such as drug and pesticides delivery devices, dialysis, ultrafiltratiaon and reverse osmosis membranes, implants in surgery and dentistry and the like.

Lightly cross-linked polyurethane hydrogels based on poly(alkylene ether) polyols

Abstract: To produce the hydrogel polymer from the above isocyanato terminated prepolymer, one reacts this prepolymer with a crosslinking agent to effect a light degree of crosslinking. The term lightly crosslinked hydrogel polymer signifies a hydrogel that contains not more than an average of about one crosslink unit per 50,000 average molecular weight of the hydrogel. Preferably there is an average of about one crosslink unit for each 100,000 to 300,000 hydrogel molecular weight and more preferably about one crosslink unit for each 150,000 to 250,000 hydrogel molecular weight. As previously indicated, the suitable crosslinkers are water or the organic polyamines, such as the primary or secondary diamines or triamines. The polyamines can be any of the known aliphatic or aromatic polyamines such as ethylene diamine, diethylene triamine, propylene diamine, hexamethylene diamine, methylene bis(aniline), tolylene diamine, isophorone diamine, trimethylpentane diamine, aniline-formaldehyde adduct polyamines, and the like. The amount of crosslinking agent used is an amount sufficient to react with all of the terminal isocyanato groups and to effect a light crosslinking. The desired concentration of crosslinker is that wherein the equivalents of reactive crosslinking groups in the crosslinking agent used is equivalent to the number of equivalents of isocyanato groups present in the prepolymer. This amount should be sufficient to react with all of the isocyanato groups and crosslink the polymer but it should not be an amount which would result in end-capping of the isocyanato groups rather than crosslinking.

Process for radiation grafting hydrogels onto organic polymeric substrates

Abstract: An improved process for radiation grafting of hydrogels onto organic polymeric substrates is provided comprising the steps of incorporating an effective amount of cupric or ferric ions in an aqueous graft solution consisting of N-vinyl-2 - pyrrolidone or mixture of N-vinyl-2 - pyrrolidone and other monomers, e.g., 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, propylene glycol acrylate, acrylamide, methacrylic acid and methacrylamide, immersing an organic polymeric substrate in the aqueous graft solution and thereafter subjecting the contacted substrate with ionizing radiation.

Microporous polyurethane hydrogels, method and composites with natural and other synthetic fibers or films

Abstract: Microporous polyurethane hydrogels of high water swellability comprising lightly crosslinked polymers of isocyanate terminated prepolymers which are the reaction product of (i) poly(alkyleneoxy) polyol with (ii) organic diisocyanate that has been lightly crosslinked with (iii) water or an organic polyamine are produced by impregnating the isocyanato terminated prepolymer solution prior to contact with the crosslinking agent with a minor significant amount of a liquid non-solvent.

The New Generation of Biomedical Polymers

Abstract: Following a review of the compatibility of polymer with blood, the use of polyurethanes, hydrogels, polylactic acid, poly-α-cyanoacrylates, and polyamino acids as biomedical polymers is discussed.

Preparation and Application of Radiation-Grafted Hydrogels as Biomaterials

Abstract: Hydrogels refer to a class of water swollen, lightly cross-linked polymeric gels which have been mentioned often as useful biomaterials (e.g., 1,2). Although they may be used in bulk forms, as in the soft contact lens, there are many applications where the mechanical demands are too great for typical hydrogels, and then such materials are best used as coatings on stronger supports. Although some polymeric supports are readily coated by solution dip coating techniques (3), there are many polymers of biomedical interest which are not so easily coated. The technique of radiation grafting (e.g., 4) is especially suitable for depositing coatings of a wide variety of hydrophilic polymer compositions and thicknesses onto and within almost any shape or composition of support polymer (e.g., 5–14). Over the past three years* our group has been applying this method, using cobalt-60 radiation, to produce directly or precursors of a whole family of new biomaterials (6–8, 10–12). This paper describes some of the highlights of our studies; most details of materials and procedures may be found in these references.

Crystalline radiation-crosslinked hydrogels of poly(vinyl-alcohol) as potential biomaterials: a study of the properties of poly(vinyl-alcohol) hydrogels in relation to conditions of primary crosslinking by irradiation, and of secondary network reinforcement by crystallization,

Abstract: Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1974.

Covalent Coupling of Small Molecules and Proteins to Poly (2-Hydroxyethyl Methacrylate-Methacrylic Acid) Hydrogels

Abstract: It has been suggested that clinically effective therapeutic devices for the treatment of enzyme deficiency diseases could be constructed by immobilizing enzymes to a surface over which a patient’s blood is then passed. Such a surface must exhibit high enzyme activity and must also be biocompatible, e.g. non-toxic and thrombus resistant. We have developed techniques for preparing surfaces which might meet these criteria by radiation grafting hydrophilic monomers to various polymeric support materials (1). An initial study of the immobilization of biomolecules to such surfaces has been made (2). The monomers which were grafted in these experiments were 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAAC). The support material used was silicone rubber. The methacrylic acid provides ample reactive carboxylic acid groups at the surface for use in enzyme immobilization.

Investigation of the properties of primary polymer particles of freshly precipitated Fe3+ hydrogels

Abstract: 1. A new approach to the investigation of freshly precipitated Fe3+ hydrogels, based on the concepts of the polymer structure of the primary particles of the precipitate, was developed. 2. A new methodology was proposed for the study of the processes of formation and properties of precipitates of Fe3+ hydrogels, constructed on the basis of a combination of the methods of chemical and complex thermal analysis. 3. The composition of the primary particles is determined by the conditions of formation of the precipitates. At pH below 7.5, the primary particles contain anions of the salt as an element bearing a structural load, and not only playing the role of a counter ion. 4. A mechanism was proposed for the formation of primary particles of precipitates of Fe3+ hydrogels from polymer subunits with the structure and composition characteristic of the given hydroxide.