Thermophysical property modifications in functional polymers via lanthanide trichloride hydrates

Fourteen water‐soluble trivalent metal chlorides from lanthanum to lutetium in the 1st‐row of the f‐block form complexes with poly(vinylamine) and increase the glass transition temperature from 57°C to well above 100°C at very low molar concentrations of the lanthanide. The large ionic radii of these hard‐acid cations allow several hard‐base amino sidegroups in the polymer to occupy sites in the first shell coordination sphere via ion‐dipole (i.e., electrostatic) interactions, which leads to microclustering of the ligands about a single metal center. The enhancement in the glass transition temperature is explained in terms of multi‐functional coordination crosslinklng. f‐Block salts induce larger increases in T_g, relative to transition metal‐complexes from the d‐block, however CoCl₂(H₂O)₆ performs comparably to some of the more efficient lanthanides. Blends of poly(vinylamine) and trimethoxysilyl‐propylpoly(ethylene imine)hydrochloride form complexes with europium(III) and exhibit synergistic single T_g response. Since lanthanides form very stable complexes with chelating (i.e., bidentate) oxygen ligands, it is possible to increase the elastic modulus of commercially important copolymers of ethylene and methacrylic acid via Eu³⁺ complexation with the carboxylate anion. This claim is verified by infrared spectroscopy. Temperature and pH‐sensitive applications for drug delivery and removal of contaminants from wastewater streams should increase the utility of these lanthanide complexes.     

Generation of long waves in ice-covered lakes by moving disturbances of atmospheric pressure

The effect of ice cover on the oscillations of water in a two-dimensional constant-depth basin within the linear theory of long waves is considered. The ice cover is treated as thin elastic plate in the presence of compressive force. The ice is fastened hardly to a shore. The eigenfrequencies and eigenfunctions of free oscillations (seishes) are obtained. The forced oscillations of fluid and ice cover under the action of a moving disturbance of atmospheric pressure are investigated. The input data are taken to have values typical of Lake Baikal. The time dependence of total mechanical energy of the fluid is calculated for different velocities of pressure motion. The variations in ice-bending stresses are determined and the causes of shore-ice breaking are explained.

     

Silyl Modification of Biologically Active Compounds. 14. Organosilicon Lipid-like Derivatives of Hydroxyethyl Tetrahydro(iso)quinoline and Thiazole with Antitumour,Antibacterial and Antifungal Properties

Silicon - A series of novel lipid-like O- and N-(3-trimethylsilyl)propyl derivatives of N-(2-hydroxyethyl)-1,2,3,4-tetrahydroquinoline, -tetrahydroisoquinoline and...