SYNTHESIS OF CONJUGATED POLYMERS VIA RANDOM COPOLYMERIZATION TO INVESTIGATE THERMAL PROPERTIES

Open Access
Author:
Gill, Michael
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Enrique Daniel Gomez, Thesis Supervisor
  • Scott Thomas Milner, Honors Advisor
Keywords:
  • conjugated polymers
  • organic-photovoltaics
  • PPTBT
  • PPT6BT
  • PFTBT
  • PFT6BT
  • copolymers
  • crystallinity
  • liquid-crystalline
  • differential scanning calorimetry
  • synthesis
  • Suzuki polycondensation
Abstract:
The utility of conjugated polymers stems from their wide uses in organic photovoltaics, organic field-effect transistors, and organic light-emitting diodes. One of the advantages of conjugated polymers over traditional silicon-based electronics is their chemical tunability. Conjugated polymers can be customized to have desirable properties based on their intended application. These polymers have been studied to understand how changes to their structure affect electronic properties, including analysis of their glass transition and melting transition; however, these models have not been extensively studied. In this study, two polymers, Poly-((2,5- dihexylphenylene)-1,4-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2’,2"-diyl) (PPTBT) and Poly-((9,9-bis(2-octyl)-fluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5′,5″-diyl) (PFTBT) were synthesized with varying concentrations of 4,7-bis(5-bromo-4-hexylthiophen-2-yl)-2,1,3-benzothiadiazole (T6BT). This was done to analyze how the random addition of T6BT affects the physical macroscopic properties of the polymers including crystallinity and the phase transition temperatures. Addition of T6BT was expected to improve the solubility of the polymer during processing with minimal impact on thermal properties. Thermal analysis was conducted using Differential Scanning Calorimetry. Poly-((2,5-dihexylphenylene)-1,4-diyl-alt-[4,7-bis(3-hexylthiophen-5-yl)-2,1,3-benzothiadiazole]-2′,2′′-diyl) or PPT6BT demonstrated a liquid crystallinity with a nematic to isotropic transition at 146C while no other polymers demonstrated substantial crystallinity or liquid crystalline properties.