Cholesteryl blue phase transitions

Different phase transitions involving blue phases are expected theoretically to be first-order [54] except the BPm to isotropic transition which could become second order [54] in an isolated critical point at the termination of a first-order line [6, 55], Figure 10 shows Cp results of cholesteryl non-nanoate (CN) with adiabatic scanning calorimetry [56]. From Fig. 10 it is clear that there are substantial pretransitional heat capacity effects associated with the BPm-I transition, which means that a large amount of energy is going into changing the local nematic order. The other transitions appear as small, narrow features on the BPm-I transition peak. From the inspection of the en-... 

Figure 10. General overview for the reduced heat capacity per mole Cp/R for a temperature range covering all phase transitions involving the blue phases in cholesteryl nonanoate (CN) [56].

Figure 11. Detailed plot of the enthalpy near the phase transition from the blue phase III to the isotropic phase in cholesteryl nonanoate (CN). Note that for clarity a large linear background 140 R (T-T ) with Tg = 90.73°C, has been subtracted from the direct data. The two vertical dashed lines indicate the width of the two-phase region [56],...

Further specific volume measurements with chiral mesogens, cholesteric, and blue phases have been made [26-28, 159-161]. The influence of chiral dopants on C/A and C/N phase transitions has been studied [37, 162]. Earlier studies, particularly on cholesteric mesophases and their mixtures, have been published, for example, for cholesteryl acetate [163], cholesteryl myristate [53], cholesteryl nonanoate [54], cholesteryl... 

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