Cellulose-spin crossover particle composite papers with reverse printing performance: a proof of concept

We report on a thermochromic paper with reverse printing performance. The paper was elaborated by combining spin-crossover particles of [Fe(NH(2)trz)(3)]Br-2 or [Fe(Htrz)(2)(trz)]BF4 and linter cellulose fibers using standard paper-making processes. The composites were characterized by electronic and vibrational spectroscopy, thermogravimetry, calorimetry, tensile tests, elemental analyses as well as by electronic and optical microscopy. The composite cellulose sheets maintain good mechanical and thermal properties and show perceptible thermochromic effects associated with a memory effect. They are rewritable by laser heating and completely erasable over several hundreds of printing cycles providing scope for inkless printing technologies.