Abstract:
A method for making polyethylene aerogels, including high molecular weight aerogels, commences by in a hydrocarbon solvent (e.g., toluene or benzene) in which polyethylene is insoluble at room temperature, adding polyethylene to the solvent heated to a temperature at which said polyethylene is soluble to form a reaction mixture. A free-radical catalyst is added to the reaction mixture and the reaction mixture is held until the desired gelation of the polyethylene has been achieved. The reaction mixture is cooled to about room temperature; and the hydrocarbon solvent is replaced with a gas (e.g., CO2 or air) to form the polyethylene aerogel. Optionally, the cooled reaction mixture can be contacted with an anti-solvent for polyethylene to replace the hydrocarbon solvent with the anti-solvent. Silica aerogel particles can be encapsulated in polyethylene aerogel by adding the particles to the polyethylene gelation reaction mixture.
Abstract:
Disclosed is a method for making a polymer or copolymer aerogel product by forming an aerogel polymer or copolymer solution in the presence of a polymer or copolymer catalyst and solvent therefor. The aerogel polymer or copolymer solution is drained onto a spinning disk or cup. The solvent is removed under aerogel forming conditions to produce the aerogel fiber web or yarn product.
Abstract:
Polyethylene aerogels and aerogel fiber webs have a high degree of molecular alignment and interconnected fibers, which offer good mechanical strength and high porosity with open interconnected three-dimensional pore structure of the aerogel fibers. The high porosity of the aerogel fibers forming the web, offer a distinct advantage over solid fibers and fiber webs formed from polymer melts, or other non-gel form of polymer solutions. In this procedure, the polymer in solution is made into cross-linked gel with three-dimensional open pore structure before introducing it to the fiber web making process.
Abstract:
Scaffold comprises a polymer defining macropores and comprising hydroxypropylcellulose partially substituted by a substituent comprising a self-crosslinkable group, which is crosslinked through the self-crosslinkable group. The macropores have an average pore size larger than 50 microns and are at least partially interconnected. In one method, bicontinuous emulsion comprising a continuous aqueous phase and a continuous polymer phase is formed. The polymer phase comprises hydroxypropylcellulose partially substituted by a substituent comprising a self-crosslinkable group, and is crosslinked through the self-crosslinkable group to form a polymer defining at least partially interconnected pores. In another method, phase separation is induced in a solution comprising a polymer precursor and water to form a bicontinuous emulsion comprising a continuous polymer phase and a continuous aqueous phase. The polymer precursor comprises a self-crosslinkable group and is crosslinked through the self-crosslinkable group in the emulsion to form a polymer defining at least partially interconnected macropores.
Abstract:
The invention relates to articles of manufacture comprising spongeous matrices which may have a controlled pore size and/or distribution, formed of: Component (a) glucomannan; and Component (b) at least one other aqueous gel-forming polysaccharide; and optionally Component (c) at least one water soluble hydrocolloid other than the foregoing. The invention also relates to processes for fabricating the spongeous matrices and their use as plant culture media, as surgical sponges, and as packaging material.