Thermal Paper and Time Temperature Integrators Made From a Structural Colored Polymer Crosslinked With Hydrogen Bonded Cyclohexanoic Acid Derivatives

Abstract

Hydrogen‐bonded cyclohexanoic derivatives are applied in a structural colored cholesteric liquid crystal (CLC) helical polymer that demonstrates an extraordinary dual thermal response. Integration of the dynamic hydrogen‐bonded cyclohexanoic acid derivatives in the CLC polymer as supramolecular crosslinks yields an immediate and irreversible loss of the green structural color upon exposure to temperatures above the cholesteric‐to‐isotropic transition temperature (TNI) caused by the helical order loss. Exposure to temperatures below the TNI yields a gradual irreversible red color shift of the reflected wavelength over broad temperature and time ranges. Most likely due to polymerization confinement in combination with the dynamics of the carboxylic acid hydrogen bonds, helical unwinding takes place over time causing the red shift of the reflected wavelength. The temperature response can be programmed by altering the chemical composition of the liquid crystal mixture. Furthermore, the green, structural color of the polymer can also be easily changed making it possible to print different colored indicators combined with different respective temperature responses on a single substrate. The printed optical sensors can be easily delaminated by dissolving the non‐covalent crosslinked polymer. Such optical polymer materials are attractive for easy processable time–temperature integrators and thermal paper.

Fully (Re)configurable Interactive Material through a Switchable Photothermal Charge Transfer Complex Gated by a Supramolecular Liquid Crystal Elastomer Actuator

“…44−47 As another example, consider CTC-LCEs acting first as soft actuators and later repurposed as reusable optical sensors (Figures S15 and S16). 48,49 Our results show that merging the self-assembly of molecules and supramolecular polymers results in a new class of interactive, sustainable materials with coupled and gated responses.…”

“…The (re)­configuring of materials into different forms and performing new functions could help reduce the generation of waste that becomes space junk. − As another example, consider CTC-LCEs acting first as soft actuators and later repurposed as reusable optical sensors (Figures S15 and S16). , Our results show that merging the self-assembly of molecules and supramolecular polymers results in a new class of interactive, sustainable materials with coupled and gated responses.…”

Principle, development and application of time–temperature indicators for packaging

“…The attachment of the ink on the substrate was realized through the gelling interaction between borax and guar gum. Foelen et al 65 reported a TTI prototype by inkjet printing cholesteric liquid crystal polymers with dual thermal responsiveness.…”

“…The attachment of the ink on the substrate was realized through the gelling interaction between borax and guar gum. Foelen et al65 reported a TTI prototype by inkjet printing cholesteric liquid crystal polymers with dual thermal responsiveness.5 | APPLICATIONS OF TTIS5.1 | MeatMeats are significant nutrients of human's dietary structure, whose safety and quality are frequently secured by cold chain transportation.Meat transportation is involved with different temperature requirements, for example, frozen (below À18 C) and chilled (4 C-8 C) transportations 66. Keeping at a low temperature has always challenged the long-term performance of TTIs used in the frozen transportation.…”

Hydrogen‐Bonded Liquid Crystal Elastomers Combining Shape Memory Programming and Reversible Actuation

“…The corresponding LCEs, named LCE-COOH and LCE-OH, contain the functionalized chain extenders and dodecylamine in a 1:1 ratio, whereas an LCE with only dodecylamine chain extender (LCE-C 12 ; no ability to form hydrogen bonds) is used as a reference. The COOH groups are known to form relatively strong hydrogen-bonded dimers [69][70][71][72] while the aliphatic hydroxyl groups are anticipated to form very weak contacts. [73] Disperse Red 1 (DR1) was added to the polymerizable mixtures at 1 wt% concentration to enable photothermal actuation of the LCEs.…”