# Crystallization Kinetics of an Equimolar Liquid Crystalline Mixture and Its Components
## 4 Summary and Conclusions  
Two liquid crystalline compounds with the acronyms MHPOBC and 3F2 HPhF6 were used to formulate an equimolar mixture, denoted as MIX2 HF6. The phase sequences of the pure compounds and their mixture were investigated using the DSC, POM, XRD, and BDS methods. The kinetics of the melt crystallization in non-isothermal conditions (various cooling rates) and isothermal conditions (various crystallization temperatures) was investigated by DSC. The main conclusions regarding the behavior of the mixture and its components are as follows:  
* According to the DSC and XRD results, the investigated MHPOBC sample exhibits the SmA\({}^{*}\), SmC\({}_{A}\)\({}^{*}\), and hexatic SmX\({}_{A}\)\({}^{*}\) phases. At least one smectic phase between SmA\({}^{*}\) and SmC\({}_{A}\)\({}^{*}\) is visible in a narrow temperature range in the DSC thermograms. Based on the BDS spectra, the phase sequence is probably SmA\({}^{*}\rightarrow\) SmC\({}_{\alpha}\)\({}^{*}\rightarrow\) SmC\({}^{*}\rightarrow\) SmC\({}^{*}\rightarrow\) SmC\({}_{A}\)\({}^{*}\). Figure 15: TTT diagram of the initialization time (**a**), activation plot of the characteristic crystallization time (**b**), and Avrami parameter as a function of crystallization temperature (**c**), determined by DSC for MIX2 HF6 and its components. The legend in (**a**) applies to all panels. Open and solid symbols correspond to the first and second crystallization stages, respectively. * The equimolar mixture MIX2 HF6 shows the SmA*, SmC*, and SmC\({}_{\text{A}}\)* phases. The experimental results do not indicate the presence of SmC\({}_{\text{A}}\)*, SmC\({}_{\text{Y}}\)*, and SmX\({}_{\text{A}}\)*. * While the pure components crystallize easily during cooling, MIX2 HF6 shows only partial crystallization, and the remaining supercooled SmC\({}_{\text{A}}\)* phase forms glass at \(T_{S}\) = 241.5 K. The glass softening during heating occurs at a slightly higher temperature of ca. 245 K. The energy released during cold crystallization upon slow heating of a quickly cooled sample, as obtained by the modulated-temperature DSC method, equals 3.8 kJ/mol (6.1 J/g). * The melt crystallization kinetics is usually controlled by the nucleation rate for the pure components (effective activation energy \(E_{\mathit{eff}}<0\)), although in certain conditions, the diffusion rate has a dominant contribution to the overall crystallization kinetics (\(E_{\mathit{eff}}>0\)). Meanwhile, the melt crystallization of MIX2 HF6 is controlled by the nucleation rate in all the tested conditions. MIX2 HF6 crystallizes at lower temperatures and a lower rate than the pure compounds. * The melting temperature of MIX2 HF6, \(T_{m}\) = 308 K, is also lowered compared to 352 K for MHPOBC and 326 K for 3F2 HPhF6. However, in some DSC thermograms of MIX2 HF6, small fractions of the crystal phases with higher \(T_{m}\) = 325 K and 328 K are observed. This is attributed to minor inhomogeneities in the mixture's composition, which occur supposedly in the solid state. Nevertheless, the stability range of the antiferroelectric SmC\({}_{\text{A}}\)* phase in MIX2 HF6 is broader than in its components. The next planned step is to mix the MHPOBC compound with higher 3 FmHPhF6 homologs, and to investigate of the influence of the C\({}_{\text{m}}\)H\({}_{\text{2m}}\) chain length on the phase sequence and glass-forming properties of the obtained mixtures. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app142411701/s1](https://www.mdpi.com/article/10.3390/app142411701/s1)]([https://www.mdpi.com/article/10.3390/app142411701/s1](https://www.mdpi.com/article/10.3390/app142411701/s1)); Figure S1: POM results for MHPOBC at 5 K/min; Figure S2: POM results for 3F2 HPhF6 at 5 K/min; Figure S3: POM results for MIX2 HF6 at 5 K/min; Figure S4: POM results for MIX2 HF6 at 30 K/min. Conceptualization, A.D. ([PERSON]); formal analysis, A.D. ([PERSON]) and A.P. ; investigation, A.D. ([PERSON]), A.P., A.D. ([PERSON]) and E.J.-G.; resources, M.P. and M.U.