Liquid Crystal Elastomer Studies
Creator: Kayla Lee Hayes
Supervisor: Peter Yeadon
Partner: Soft Matter Lab at the University of Rhode Island
The objective of this study was to investigate the bonding performance of various adhesives on carbon black liquid crystal elastomer (LCE) samples and to examine the thermal response of the material under controlled curvature conditions.
Adhesive Evaluation
A series of adhesives were tested for their effectiveness in bonding LCE samples, including a cement for ABS and styrene, rubber cement, scenic cement, turpentine (as a paint stripper substitute), and cyanoacrylate (super glue). Among these, cyanoacrylate demonstrated the highest bonding strength and stability. It effectively adhered LCE samples to one another without displacement during curing. The adhesive maintained integrity even after repeated submersion in water at temperatures up to 90 °C, indicating strong thermal and chemical resistance under elevated humidity conditions.
Thermal Response Experiment
For the thermal response analysis, a custom jig was fabricated to hold two LCE samples in a gently curved configuration during curing. The samples were cured for exactly three hours, then subjected to two thermal cycles and bonded using cyanoacrylate. The original objective was to evaluate the material’s buoyancy and potential as a temperature indicator when floating on water. However, subsequent observations revealed that at elevated temperatures, the material consistently exceeded the curvature radius of the original jig.
Results and Observations
The LCE samples exhibited distinct curvature changes in response to temperature variations. At temperatures between approximately 67.5 °C and 92 °C, the material bent over onto itself. Around 53 °C, the curvature tightened beyond that of the initial mold, whereas at approximately 45 °C, the curvature matched the radius of the original jig. The samples responded immediately to temperature changes, ceasing motion after roughly 3 seconds. Upon removal from the heated environment, the LCEs began to relax and return to a linear configuration.
At 67.5 °C, the 3 cm sample required approximately 20 seconds to fully straighten, while the 4 cm sample required 30–35 seconds. These findings suggest that higher temperatures imparted sufficient thermal energy to cause an overshoot in curvature and that the material’s heat retention capacity was relatively low. The observation that the curvature matched the jig radius at a temperature substantially below the activation temperature remains unexplained. It is hypothesized that the duration of the curing process may influence the activation temperature of the LCE, potentially affecting its thermal response characteristics.
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