Karl Friedrich Mueller

Thermotropic aqueous gels and solutions of N,N-dimethylacrylamide-acrylate copolymers

Abstract Copolymers of N,N-dimethylacrylamide (DMA) with C1–C4 alkyl and alkoxyethyl acrylates form aqueous solutions with lower critical solution temperatures (LCST) between 0 and 100°C. As weakly crosslinked gels they exhibit strong cloud points and volume shrinkage with rising temperature. Copolymers of DMA with higher alkyl acrylates are insoluble down to 0°C, but form hydroplastics and hydrogels with strong cloud points. The LCST is determined by the hydrophobicity and amount of comonomers. The ability of these copolymers to form aqueous solutions with LCSTs can be attributed to a random copolymer structure, which allows an abrupt phase transition from a fully hydrated to a predominantly hydrophobically interacting polymer.

Periodic Interfacial Precipitation in Polymer Films

Interfacial precipitation of silver halides in water-swollen polymer films occurred in complex, multilayered patterns if the concentrations of counterdiffusing reactants were unequal or decreased at different rates. Development of the rapidly forming Liesegang rings, which extend the phenomenon of periodic precipitation to the submicrometer range, is attributable to the combined effect of a moving reaction zone and periodic immobilization of colloidal silver halide.

Polyurethanes derived from oligoperfluoroalkyl alcohols

Di-, tri- and poly-perfluoroalkyl-substituted alcohols and acids and derivatives thereof are described which are prepared from perfluoroalkyl iodides and di-, tri- or polyallyl alcohols or acids. These compounds contain two or more perfluoroalkyl-iodoalkyl or perfluoroalkyl-alkenyl groups and one or two alcohol or acid groups or derivatized alcohol or acid functions. They can be reacted with isocyanates, epoxy compounds, anhydrides, acids or acid derivatives to prepare a great variety of oil- and water-repellent compositions which are useful for oil- and water-repellent treatment of textiles, glass, paper, leather and other substrates.