Effect of Calendering and Surface Treatment on the Thermochromic Response of Cholesteric Liquid Crystals on PET Nonwovens

Smart textiles with temperature‐sensing capabilities have attracted much attention due to their facile temperature monitoring in healthcare and packaging industry. This study explores the deposition of thermochromic cholesteric liquid crystal (CLC) on PET nonwoven using direct ink writing (DIW), focusing on the influences of calendering and surface treatment, such as hydrophilic PVA and hydrophobic NeverWet coatings. Wetting studies show that the porous nonwoven promotes rapid CLC absorption, while calendering the uncoated nonwoven accelerates the ink absorption despite the reduced pores and air permeability. Surface chemistry further affects the CLC behavior, with PVA enhancing wetting and NeverWet suppressing both wetting and absorption. As a result, NeverWet coating significantly improves the thermochromic performance with a ~260% increase in the peak perceptual lightness (L*) for both calendered and non‐calendered substrates. PVA‐coated non‐calendered nonwoven shows a slightly lower peak L* (~12% decrease) compared to its uncoated counterparts, however, the synergistic effect of PVA coating and calendering results in an increase of ~160% in the peak L* value due to suppression of absorption. The color intensities of Red, Green, and Blue (RGB) follow similar trends. The findings highlight the importance of controlling CLC–substrate interactions and demonstrate its potential for wearable temperature sensing applications.