Self-assembling behaviour of new functional photosensitive cinnamoyl-based reactive mesogens

ABSTRACT

One of the most exciting classes of organic materials that is able to self-assemble at nanoscopic scale are those exhibiting the liquid crystalline (LC) behaviour which can be distantly tuned by an external stimulus. Under UV/Vis light irradiation, the reversible photoisomerisation process can take place if the compounds possess the photosensitive group, e.g. N=N or cinnamoyl group incorporated in their molecular structure. This can drastically affect the LC behaviour. However, the compounds possessing the cinnamoyl fragment with C=C double bond are capable of both photoisomerisation and photocycloaddition processes. Several cinnamoyl-based reactive mesogens with polymerisable vinyl group have been designed; their mesomorphic and structural behaviour have been studied. Depending on the molecular structure, the reactive mesogens exhibit nematic, orthogonal smectic A and tilted smectic C phases; the kinetics of the phase transition temperatures has been checked. The structure of the mesophases is confirmed by small-angle X-ray scattering. The main objective of the present work is to contribute to better understanding of molecular structure – mesomorphic property relationship for new functional cinnamoyl-based photosensitive reactive mesogens which can be further used for design of smart self-assembling macromolecular materials.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystal
• reactive mesogen
• cinnamoyl group
• photosensitive materials
• self-assembling behaviour

Acknowledgments

Authors greatly acknowledge the financial support from: Czech Science Foundation [Project No. CSF 19-03564S], Ministry of Education, Youth and Sports of the Czech Republic [Project No. LTC19051] and Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports [Project No. SOLID21 - CZ.02.1.01/0.0/0.0/16_019/0000760]. Authors (N.S. and A.B.) are grateful to support of fellowship No.: 3.029 “Studium fázových přechodů nových kapalně krystalických materiálů” under “Open science 2018” programme of the Czech Academy of Sciences.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Czech Science Foundation [19-03564S]; Ministry of Education, Youth and Sports of the Czech Republic [LTC19051]; Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports [SOLID21 - CZ.02.1.01/0.0/0.0/16_019/0000760]; ‘Open science 2018’ programme of the Czech Academy of Sciences [3.029].