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 Tg, 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 Tg 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.