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Cholesteric liquid crystal oligomers are widely researched for their interesting thermochromic properties. However, structure-property relationships to program the thermochromic properties of these oligomers have been rarely reported. In this work, we use the versatile thiol-ene click reaction to synthesize a series of hetero-oligomers and study the impact of different compositions on the thermochromic behavior of the resulting material. Characterization of the oligomers shows significantly different rates of reaction for the monomers despite their very similar structures, which leads to oligomer compositions that do not match the original reaction feed. The oligomers are then used to produce thin near-infrared reflecting coatings. The best-performing thermochromic reflector has a room-temperature reflection band that shifts a total of 510 nanometers upon heating to 120 °C. The shift is repeatable for up to 10 times with no appreciable degradation. The room temperature reflection of the coatings is shown to be tunable not only by adjusting the chiral dopant concentration but also by the ratio of the monomers. Finally, we show that the oligomers can be chemically modified by making their reactive end groups undergo a reaction with monothiol compounds. These modifications allow for further fine-tuning of liquid crystal oligomers for heat-regulating window films, for example., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The UV intensity during photopolymerization allows control over the structural color of a cholesteric liquid crystal (CLC) polymer photonic coating in a single step. Simultaneously, the glass transition temperature ( T g ) of the polymer can be tuned by the applied UV intensity. Most likely the low intensity photopolymerization increases the inhibition time, leading to in situ formation of polymer fragments through oxygen inhibition. The formation of polymer fragments changes the matrix during the inhibition time, which results in a color change before the polymer network is formed. Additionally, these fragments inside the network act as a plasticizer, effectively lowering the T g . This method can be combined with temperature responsive properties based on shape memory to fabricate photonic coatings with multiple, responsive colored patterns. The presented work allows for new functionalities in responsive photonic polymers as multiple colors and response temperatures can be incorporated in a single polymerization step.