Dynamic Pressure Sensitive Adhesion in Nematic Phase of Liquid Crystal Elastomers

Abstract

We explore the correlation between the anomalous mechanical dissipation and the pressure-sensitive adhesion in nematic liquid crystalline elastomers (LCEs), comparing hard glassy and soft materials (high and low crosslinking density, respectively) and nematic vs. isotropic genesis. Two significant factors are identified contributing to strong adhesion: the intrinsic damping, which is high in the nematic phase, and the surface roughness, which is affected by the elastomer genesis. At the same time, we find that surface energy plays only a minor role in pressure-sensitive adhesion. Theoretical calculations of dynamic adhesion are carried out by summing over the full range of frequencies in the dynamic-mechanical Master Curves data, and by averaging over surface roughness in soft and hard regimes, the results fitting the measured data with quantitative accuracy. Finally, we demonstrated that the adhesion strength in LCEs altered by controlling the nematic phase temperature range.