Volume Phase Transitions of Heliconical Cholesteric Gels under an External Field along the Helix Axis

• Main Author: Akihiko Matsuyama
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Gels
• Subjects: liquid crystal; cholesteric gel; elastomer; volume phase transition
• Online Access: https://www.mdpi.com/2310-2861/6/4/40
• ISSN: 2310-2861

We present a mean field theory to describe cholesteric elastomers and gels under an external field, such as an electric or a magnetic field, along the helix axis of a cholesteric phase. We study the deformations and volume phase transitions of cholesteric gels as a function of the external field and temperature. Our theory predicts the phase transitions between isotropic (<i>I</i>), nematic (<i>N</i>), and heliconical cholesteric (<inline-formula><math display="inline"><semantics><mrow><mi>C</mi><msub><mi>h</mi><mi>H</mi></msub><mrow><mo>)</mo></mrow></mrow></semantics></math></inline-formula> phases and the deformations of the elastomers at these phase transition temperatures. We also find volume phase transitions at the <inline-formula><math display="inline"><semantics><mrow><mi>I</mi><mo>−</mo><mi>C</mi><msub><mi>h</mi><mi>H</mi></msub></mrow></semantics></math></inline-formula> and the <inline-formula><math display="inline"><semantics><mrow><mi>N</mi><mo>−</mo><mi>C</mi><msub><mi>h</mi><mi>H</mi></msub></mrow></semantics></math></inline-formula> phase transitions.