Stiff, tunable and reprocessable polythiourea supramolecular materials by manipulating hydrogen-bonding and metal-coordinating interactions

Abstract

Rational strategies manipulating hydrogen-bonding and metal-coordination interactions accelerate the development of supramolecular materials with unprecedented properties, such as adaptability, self-healing, stimuli-responsiveness, reprocessability and recyclability. Herein, supramolecular interactions of thioureas were fully utilized to design new materials with adjusted mechanical performances and robust reprocessability. A series of polythioureas were facilely synthesized by the co-polycondensation of CS2 and two diamines, which was an efficient and economical alternative to the isothiocyanate-based polymerization. Hydrogen-bonded polythiourea materials with tunable mechanical performances were achieved by adjusting the density and regularity of thiourea units in the polymer chains. Further incorporating tiny amount of metal salts (CuCl2, CuCl, CuBr and CuI) resulted in polythiourea materials with enhanced mechanical performances, following the trend determined by the hard-soft acid-base principle. As far as we know, this is the first report of metal-coordinated polythiourea supramolecular materials. The exploration of hard-soft acid-base principle will also provide new inspirations for designing metal-coordinated supramolecular materials.