Synthesis and characterization of plant based thiophene and 3-hexylthiophene copolymers

Abstract

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Polythiophene and its derivatives have become more desirable due to their applications in various fields. These applications arise due to their inherent properties, such ns optical and electronic conductive properties; as well as thermal and environmental stability. Precursors of polythiophenes are generally obtained from petroleum by-products, which are non-renewable. It has been reported that precursors of polythiophenes and its derivatives are naturally available in different types of Tagetes species such as Tagetes crecta, Tagetes tenuifolia, etc. A number of thiophene derivatives such as 2, 2’:5’, 2” - (crthienyl (Alpha-T), 5-(3-buten-l-ynyl)-2,20-bithienyl (BBT), 5-(4-hydroxy-l-butynyl)-2, 20-bithienyl (BBTOH), and 5-(4-acetoxy-l-butynyl)-2, 20-bithienyl (BBTOAc), were found and identified, specifically in the roots o f Tagetes species. The current study reports the polymerization of the extracted thiophene derivatives from Tagetes erecta and 3- hexylthiophene (3HT) to obtain a random copolymer o f poly (thiophenes-3- hexylthiophene). The extracted thiophene derivatives were partially purified and characterized. The mixture of plant based thiophenes and commercial 3HT with various weight compositions were selectively polymerized on the direct one-step chemical oxidative free radical polymerization to obtain co-polymers. Structural characterization of the synthetic products was done using Fourier Transformation Infrared, Proton Nuclear Magnetic Resonance, Ultra Violet Visible and X-ray Diffraction techniques. Homopolymers of polythiophene obtained from plant based thiophenes have limited processability of solar cells due to poor solubility in common organic solvents. Tlowever, a significant progress of the solubility was observed with copolymers having partial contribution of 3HT.