Methods were developed for application of thermochromic pigments to textiles, based
on printing and extrusion, for both leuco dye based and cholesteric liquid crystal
thermochromics. The leuco dye based thermochromics were assessed in terms of heat
stability, binder optimization and colour saturation using an instrumental colour
measurement system. Enhancement of lightfastness of leuco dye based thermochromics
was carried out using UV absorbers, HALS and antioxidants as additives. A
comparative study was also carried out between printing and extrusion application
methods. A colour measurement system with the facility for temperature variation was
constructed using two traditional components – a reflectance spectrophotometer and a
controllable hot stage. The dynamic colour change of leuco dye based thermochromics
with temperature was assessed. The liquid crystals were assessed with temperature for
their additive colour mixing properties by layering them over each other. They were
also assessed in terms of aspects of applications, such as differences in the over-layering
sequence and colour hysteresis on heating and cooling. The results were evaluated not
only to provide a scientific understanding of the performance but also to provide useful
information from a creative designer’s point of view.