Materials, Methods & Technologies, Volume 8, 2014

Abstract: The present study reports the development of novel thermochromic compositions based on carbocyanine (polymetine) dyes and their mixtures. The sensors of the compositions are two types, they have various temperature transitions from 25°С to 40°С and higher (in first type) and from T = -10ºC to 0ºC (in second type). Both types differ in compositions and preparing conditions. The compositions can be used in printing process like inkjet printing and flexographic methods, they can be applied on paper and polymer materials. The advantage of the development of thermochromic compositions is that they have no need of manufacture microencapsulated systems. But just how the microencapsulated ones they can be used for "smart packaging". Morphology, chemical structure and spectral properties of thermochromic films were investigated by SEM, XPS and reflectance spectroscopy. The mechanism of the thermochromic transitions is based on controlled formation / destruction of organic molecular crystals known in literature as J-aggregates.