Water-soluble poly(phenylene ether) derivatives as environmentally benign and heat-resistant coating materials for paper

Functional and environmentally benign water-soluble polymers which have characteristic heat-resistant properties, mechanical strength values, and depolymerization capabilities were designed by introducing ionic groups as side chains to poly (phenylene ether)s (PPE). Two water-soluble PPE polymers were prepared by oxidation of 3-methylsalicylic acid and 5-methylsalicylic acid. They were evaluated as functional coating materials for paper production. The compounds showed important characteristics as paper coating materials: high solubility in alkaline water, low viscosity values of polymer solutions and mixtures with inorganic pigments at high shear rates, and adhesion to pulp fiber and inorganic pigments. High glass transition temperature values of the compound provided stiffness and strong resistance against heat blocking of sheet media when a thin layer of compound was applied to a surface of a paper sheet. Additionally, the compounds were found to depolymerize into oligomers by oxidation in the presence of methylsalicylic acid monomers. Such properties of the water-soluble PPE polymers allowed applications to advanced strong and recyclable coating materials.