An unconventional modulated differential scanning calorimetric (MDSC) technique was used to determine the thermal properties of a binary mixture composed by the chiral and achiral liquid crystalline molecules. The chiral calamitic host compound 4-(octyloxy) phenyl 3-methoxy-4-((4-((2-(pentyloxy) propanoyl)oxy) benzoyl) oxybenzoate, denoted as QVE 8/5 and the hockey stick-shaped compound (E)-4-((E-((3-(decyloxy)-2-methylphenyl)imino) methyl) phenyl 3-(4-(dodecyloxy) phenyl) acrylate, denoted as H-22.5 was used as an achiral guest. The phase diagram of this self-organized molecular system includes isotropic (Iso), blue phase III (BPIII), cholesteric (N), twist grain boundary smectic-A (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14156_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{TGB}}_{\text{A}}^{}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mtext>TGB</mtext> <mrow> <mtext>A</mtext> </mrow> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation>) and tilted ferroelectric smectic-C (SmC) phases. The temperature dependence of the enthalpy and the heat capacity of four binary mixtures exhibiting Iso-BPIII, BPIII-N, N-<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14156_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{TGB}}_{\text{A}}^{}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mtext>TGB</mtext> <mrow> <mtext>A</mtext> </mrow> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14156_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{TGB}}_{\text{A}}^{}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mtext>TGB</mtext> <mrow> <mtext>A</mtext> </mrow> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation>-SmC phase transitions are reported. The results allow the evaluation of the order of several chiral liquid crystalline phase transitions and their critical behaviour. The BPIII-N and N-<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14156_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{TGB}}_{\text{A}}^{}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mtext>TGB</mtext> <mrow> <mtext>A</mtext> </mrow> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation> phase transitions are found to be close to the tricritical point. Tricritical points are characterized by the absence of latent heats, phase shift peaks and critical exponents (α) close to 0.5. The <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14156_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{TGB}}_{\text{A}}^{}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mtext>TGB</mtext> <mrow> <mtext>A</mtext> </mrow> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation>-SmC and SmC-<InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14156_Article_IEq6.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="45" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{SmC}}_{\text{A}}^{*}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mtext>SmC</mtext> <mrow> <mtext>A</mtext> </mrow> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation> phase transitions show no latent heat. The critical exponents and amplitude ratios A−/A+ fall within the range of 0.245–0.388 and 1.04–1.14, respectively, supporting the second-order nature of these phase transitions.

Thermal analysis of induced frustrated blue phase and twist grain boundary phase in chiral–achiral self-organizing system by modulated differential scanning calorimetry

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发表日期：

2025年3月24日

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Smriti Mitra,
Akhileshwar Prasad,
Malay Kumar Das,
Banani Das,
Vera Hamplova,
Alexej Bubnov

摘要

An unconventional modulated differential scanning calorimetric (MDSC) technique was used to determine the thermal properties of a binary mixture composed by the chiral and achiral liquid crystalline molecules. The chiral calamitic host compound 4-(octyloxy) phenyl 3-methoxy-4-((4-((2-(pentyloxy) propanoyl)oxy) benzoyl) oxybenzoate, denoted as QVE 8/5 and the hockey stick-shaped compound (E)-4-((E-((3-(decyloxy)-2-methylphenyl)imino) methyl) phenyl 3-(4-(dodecyloxy) phenyl) acrylate, denoted as H-22.5 was used as an achiral guest. The phase diagram of this self-organized molecular system includes isotropic (Iso), blue phase III (BPIII), cholesteric (N^*), twist grain boundary smectic-A^* ( ${\text{TGB}}_{\text{A}}^{*}$ ${TGB}_{A}^{*}$ ) and tilted ferroelectric smectic-C^* (SmC^*) phases. The temperature dependence of the enthalpy and the heat capacity of four binary mixtures exhibiting Iso-BPIII, BPIII-N^*, N^*- ${\text{TGB}}_{\text{A}}^{*}$ ${TGB}_{A}^{*}$ and ${\text{TGB}}_{\text{A}}^{*}$ ${TGB}_{A}^{*}$ -SmC^* phase transitions are reported. The results allow the evaluation of the order of several chiral liquid crystalline phase transitions and their critical behaviour. The BPIII-N^* and N^*- ${\text{TGB}}_{\text{A}}^{*}$ ${TGB}_{A}^{*}$ phase transitions are found to be close to the tricritical point. Tricritical points are characterized by the absence of latent heats, phase shift peaks and critical exponents (α) close to 0.5. The ${\text{TGB}}_{\text{A}}^{*}$ ${TGB}_{A}^{*}$ -SmC^* and SmC^*- ${\text{SmC}}_{\text{A}}^{*}$ ${SmC}_{A}^{*}$ phase transitions show no latent heat. The critical exponents and amplitude ratios A⁻/A⁺ fall within the range of 0.245–0.388 and 1.04–1.14, respectively, supporting the second-order nature of these phase transitions.