Synthesis, thermal stability, optical and electrochemical properties of halogen terminated azo-benzothiazole mesogen containing smectic side chain liquid crystalline polymers

  • Md. Rabiul Karim
  • Rosiyah Yahya
  • Md. Rezaul Karim Sheikh
  • Noordini M. Salleh
  • Aziz Hassan
  • H. N. M. Ekramul Mahmud
Original Paper


Azo-benzothiazole mesogen containing two new polymerizable liquid crystalline (LC) methacrylate macromers M1-M2 having terminal halogen atom (F and Cl) at the sixth position on the benzothiazole moiety and their side chain liquid crystalline polymers (SCLCPs) P1-P2 were synthesized and characterized. The thermal stability, mesomorphic behaviour, optical and electrochemical properties were investigated. Thermogravimetric analysis revealed that the prepared macromers and polymers showed good to excellent thermal stability with decomposition temperature (T d) corresponding to 5 % weight loss in the range of 282–312 °C. The DSC and POM observations confirmed the presence of smectic LC phase in both of the macromers and polymers. The isotropization temperatures and mesophase stability were influenced by the terminal halogen atom situated in the mesogen. Optical investigations demonstrated that polymers P1-P2 showed strong absorption band around 398–403 nm and exhibited blue fluorescence emission. From cyclic voltammetric studies the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of P1-P2 were found in the range of −5.86 to −5.70 eV and −3.36 to −3.22 eV respectively.


Azo-benzothiazole Smectic phase Side chain liquid crystalline polymer Thermal stability Electrochemical property 



The authors would like to thank University of Malaya for the financial support through the research grants PV041-2012A and RG262-13AFR.


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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Md. Rabiul Karim
    • 1
  • Rosiyah Yahya
    • 1
  • Md. Rezaul Karim Sheikh
    • 2
  • Noordini M. Salleh
    • 1
  • Aziz Hassan
    • 1
  • H. N. M. Ekramul Mahmud
    • 1
  1. 1.Department of ChemistryUniversity of MalayaKuala LumpurMalaysia
  2. 2.Department of Applied Chemistry and Chemical EngineeringRajshahi UniversityRajshahiBangladesh

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