Investigation of liquid crystalline properties of new carbamate-based H-bonded materials

In this study, the properties of three different hydrogen-bonded liquid crystalline complexes named DEGME-BI-h-LC8, DEGME-MCHI-h-LC11 and EEG-MCHI-h-LC11 were investigated. These complexes were prepared using a common H-bond donor mesogens LC8 or LC11 with urethanes (which are H-bond acceptors) formed by the reaction of DEGME and EEG compounds with different isocyanates. The liquid crystal properties of the complexes were investigated using different techniques. According to the results obtained, all three complexes exhibit nematic during cooling. One of the compounds, especially DEGME-BI-h-LC8, increased its efficiency by showing mesophase during both heating and cooling. H-bond interactions in the complexes provided structural flexibility, resulting in the emergence of two different LC phases. In the study, the dielectric properties of the complexes were also investigated. As the frequency increased, the dielectric anisotropy decreased, due to the reorientation of the dipole molecules in the complex. Also, the relaxation time decreased with increasing frequency and temperature, due to increased molecular mobility in the complex. Overall, this work can assist in the development of new materials for various applications by providing information on the properties and dielectric behaviours of different hydrogen-bonded liquid crystalline complexes.