LINEAR AND HYPERBRANCHED PERYLENE-BASED POLYIMIDES: POLYMERIZATION AND HYBRIDIZATION WITH MOLYBDENUM DISULFIDE NANOSHEETS
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Saudi Digital Library
Abstract
conjugated polymers have been discovered and later recognized by a Noble Prize in 2000. Conjugated conducting polymers have unique advantages over traditional metal materials. Polythiophene with low band gap of 1.9 eV is one of the most studied polymers. However, polythiophene is a p-type polymer, and there is a need to develop n-type low band gap polymers to replace fullerene and heavy metallic materials. For this purpose: new linear, tri- and tetra- hyperbranched polyimides with tunable properties have been synthesized based on perylene dianhydride to develop high performance n-type polymers. The chosen monomers play an important role in the properties of the synthesized polymers, such as solubility, geometry, thermomechanical stability, and the enhancement of charge transfer complexes. Both perylene core and donor-acceptor atoms lead to decrease in the band gap and further to the formation of low band gap polymers similar to polythiophenes. In addition, the perylene core leads to the formation of self-assembled structures that are controlled by the solvent and enhanced via the hybridization with MoS2 as a two-dimensional filler. The conjugated nature in the designed polyimides results in a material with golden-shiny-metal-like conductive fibrils. Exfoliation of small portions of MoS2 with the polyimides significantly improves thermo-conductive properties as well as tuning the band gap due to hybridization.
Linear and hyperbranched perylene-based polyimides were synthesized through the two-step polycondensation via the poly(amic-acid) intermediates as well as in-situ polymerization. Controlling the polymers dimensional geometry resulted in decreasing the viscosity and enhancing the hybridization with MoS2. The successful formation of polyimides was confirmed by structural, thermal, and morphological characterizations using DSC, NMR spectroscopy, TGA, FT-IR and AFM.
The hydrothermal synthesis of linear and hyperbranched polyimides including the in-situ polymerization in only water without a catalyst or organic solvents was examined resulting in polyimides with unique properties. The imidization was confirmed by FT-IR, and crystals regularity was determined by optical microscopy.
The synthesized polyimides have promising applications in next generation optoelectronics and in stretchable organic devices due to the combination of tunable properties including excellent conductivity, optical and high thermal performance.