Abstract: Fluoroacylation of ethyl cellulose has been found to result in good gas permeability and blood compatibility for polymeric layers made from the resulting fluorinated esters. The fluoroacylated ethyl cellulose has good hydrolytic stability at blood pH and under sterilization conditions (e.g. 100.degree. C). For use in blood oxygenation devices, implantable biomedical devices, blood sampling or analysis or purification devices, etc., it is preferred that the fluoroacylated ethyl cellulose be substantially free of residual OH and have a fluorine content above 10% by weight (e.g. at least about 12% by weight).

Abstract: Unsupported ultrathin polymer film is made in bulk form by floating the film on a bath, transferring the floating film to a release substrate, drying the resulting film/substrate composite, separating the film from the substrate, and retrieving the unsupported film, e.g. in the form of a convoluted roll provided with anti-blocking agent in between the convolutions. The bulk product can be made into thermal insulating material, flake-like weather modifying agents, etc.