Poly(Pyridinium Salt)s Based on 2,7-Diamino-9,9-Dioctylfluorene Moieties: Synthesis, Lyotropic Liquid-crystalline and Light-emitting Properties | Chapter 6 | Current Topics on Chemistry and Biochemistry Vol. 2

 The phenylated poly(pyridinium salt)s are a kind of ionic main-chain chain polymer made through ring-transmutation polymerization of bispyrylium salts and diamines, as well as metathesis processes. Because they're utilised to make electrochromic devices, fire-retardant materials, biosensors, and even nonlinear optical devices, they're referred to as advanced functional materials. A novel class of poly(pyridinium salt)s with lyotropic liquid-crystalline and light-emitting features is described here. Using ring-transmutation polymerization and metathesis processes, a variety of poly(pyridinium salt)s-fluorene main-chain ionic polymers with different organic counterions were produced. Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers were used to determine their chemical structures. The number-average molecular weight (Mns) of these polymers ranged from 96.5 to 107.8 kg/mol, with a polydispersity index (PDI) of 1.12–1.88. At varying critical concentrations, they showed fully-grown lyotropic phases in polar protic and aprotic solvents. For one polymer, small-angle X-ray scattering suggests that 60–80 percent of the solvent component forms lyotropic structures. Depending on the counterions, all polymers displayed lyotropic liquid-crystalline phases in organic solvents (DMSO, CH3CN, or MeOH) above their critical concentrations. Within the observed LC platelets, Polymer 1 showed a square packing pattern. The light emission spectra were found to be reliant on the chemical structures of the counterions in the film states, resulting in blue light, according to the assessments of their optical characteristics. In organic solvents, the majority of them emitted green light, with the exception of a few cases where they emitted blue light in THF. The thermal properties of polymers were affected by the size of counterions, as assessed by differential scanning calorimetry and thermogravimetric analysis. Their UV-Vis absorption spectra in diverse organic solvents were almost identical, indicating that their conjugated polymer structures had closely spaced π-π* transitions.

Author(s) Details:

Pradip K. Bhowmik,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Tae S. Jo,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Jung J. Koh,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Jongwon Park,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Bidyut Biswas,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Ronald Carlo G. Principe,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Haesook Han,
Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway Box 454003, Las Vegas, NV 89154-4003, USA.

Andras F. Wacha,
Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar Tudósok körútja 2, 1117 Budapest, Hungary.

Matti Knaapila,
Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

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