Document Type
Article
Publication Date
3-12-2021
Publication Title
Molecules
Volume
26
Issue
6
Abstract
A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12-1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60-80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λem peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0-90%), and their λem peaks were blue shifted.
Keywords
Aggregation; Differential scanning calorimetry; Gel permeation chromatography; Hairy-rod polymers; Luminescence; Lyotropic liquid-crystalline phase; Metathesis reaction; Polarizing optical microscopy; Poly(pyridinium salt)s; SAXS; Thermogravimetric analysis; UV-Vis spectroscopy
Disciplines
Physical Chemistry
File Format
File Size
2853 KB
Language
English
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Repository Citation
Bhowmik, P. K.,
Jo, T.,
Koh, J.,
Park, J.,
Biswas, B.,
Principe, R.,
Han, H.,
Wacha, A.,
Knaapila, M.
(2021).
Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9'-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties.
Molecules, 26(6),
http://dx.doi.org/10.3390/molecules26061560