Conjugated Polymer Nanoparticles by Direct Arylation Polycondensation

Abstract

Conjugated polymer nanoparticles can be successfully prepared by conventional C-C cross couplings (e.g Suzuki-Miyaura, Stille etc.) in aqueous emulsion and miniemulsions.1,2,3 This thesis investigates the preparation of these conjugated polymer nanoparticle dispersions by novel C-C cross couplings utilising C(sp2)-H bonds. This direct arylation polycondensation (DArP) approach4 enables a more atom efficient preparation of semiconducting polymers in fewer synthesis steps. Judicious reaction parameter screening facilitated the formation of stable nanoparticle dispersions in the sub-micron regime with particle size dispersities (PDI) < 0.30 by increasing the hexadecane concentration. A comprehensive understanding of the influence of the reaction parameters on the molecular weight of the polymer prepared by this in-situ miniemulsion polymerisation technique was developed. Polymer molecular weights of Mn ≥ 10 kg mol-1 were controlled reproducibly by adjusting the pivalic acid and potassium carbonate concentration. The microstructure of the polymers in these nanoparticle dispersions have been analysed and the identity of any polymer backbone defects investigated. DArP is known to introduce homo coupling defects into the polymer backbone that are less prevalent in polymers prepared by more conventional C-C coupling methods.4 Hence, different analytical methods such as mass spectrometry (MALDI-TOF-MS) and NMR techniques (1H, 13C, 19F and 2D experiments) were employed to identify and quantify the defects. As a proof of principle for the applicability of the prepared dispersions, organic field effect transistors were fabricated using the aqueous dispersions. Comparison between the holistic synthesis to device fabrication in water presents a greener and scalable process for the printing of electronic devices with measured electron mobilities of μe = 0.05 cm2 V 1 s 1 for PDPPF4.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Michael Turner (Supervisor) & Leszek Majewski (Supervisor)