Dynamics and Pretransitional Effects in C₆₀ Fullerene Nanoparticles and Liquid Crystalline Dodecylcyanobiphenyl (12CB) Hybrid System

• Main Authors: Sylwester J. Rzoska, Szymon Starzonek, Joanna Łoś, Aleksandra Drozd-Rzoska, Samo Kralj
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Nanomaterials
• Subjects: liquid crystal nanoparticles; fullerenes; dielectric spectroscopy; phase transitions; dynamics
• Online Access: https://www.mdpi.com/2079-4991/10/12/2343

The report shows the strong impact of fullerene C₆₀ nanoparticles on phase transitions and complex dynamics of rod-like liquid crystal dodecylcyanobiphenyl (12CB), within the limit of small concentrations. Studies were carried out using broadband dielectric spectroscopy (BDS) via the analysis of temperature dependences of the dielectric constant, the maximum of the primary loss curve, and relaxation times. They revealed a strong impact of nanoparticles, leading to a ~20% change of dielectric constant even at <i>x</i> = 0.05% of C₆₀ fullerene. The application of the derivative-based and distortion-sensitive analysis showed that pretransitional effects dominate in the isotropic liquid phase up to 65 K above the clearing temperature and in the whole Smectic A mesophase. The impact of nanoparticles on the pretransitional anomaly appearance is notable for the smectic–solid phase transition. The fragility-based analysis of relaxation times revealed the universal pattern of its temperature changes, associated with scaling via the “mixed” (“activated” and “critical”) relation. Phase behavior and dynamics of tested systems are discussed within the extended Landau–de Gennes–Ginzburg mesoscopic approach.