Palladium‐Mediated Surface‐Initiated Kumada Catalyst Polycondensation: A Facile Route Towards Oriented Conjugated Polymers

Abstract

Palladium-mediated surface-initiated Kumada catalyst transfer polycondensation is used to generate poly(3-methyl thiophene) films with controlled thickness up to 100 nm. The palladium initiator density is measured using cyclic voltammetry and a ferrocene-capping agent, where the surface density is found to be 55% (1.1 × 10(14) molecules per cm(2)). UV-Vis spectroscopy and AFM show increased aggregation in palladium-initiated films due to the higher grafting density of palladium initiators on the surface. The anisotropy of the P3MT films is determined using polarized UV-Vis spectroscopy, which indicates a degree of orientation perpendicular to the substrate. Evidence that palladium can maintain π-complexation even at elevated temperatures, is also shown through the exclusive intramolecular coupling of both a phenyl and thiophene-based magnesium bromide with different dihaloarenes.

Functionalization of Reactive End Groups in Surface‐Initiated Kumada Catalyst‐Transfer Polycondensation

“…Not clear from a thickness increase alone, is a change in grafting density-were P3MT chains or left over initiator units being activated? A previous report by our group equates an increase in grafting density with a blue shift in the UV-Vis spectra of P3MT films, [29] resulting from H-aggregation of stretched chain conformations at higher grafting densities. In this re-initiated system, however, the UV-Vis spectrum gives no indication of increased grafting density; only the absorbance is increased.…”

Gradient Sequence π-Conjugated Copolymers

“…15). This synthetic method, now known as catalyst transfer polycondensation (CTP) (13)(14)(15)(16)(17)(18)(19), paved the way for synthesizing all-conjugated diblock copolymers (20)(21)(22)(23)(24)(25)(26)(27), star polymers (28,29) and surface-grafted polymers (30)(31)(32). CTP also provides access to all-conjugated gradient sequence copolymers (33)(34)(35)(36).…”

Poly(3-Hexylthiophene) Nanostructured Materials for Organic Electronics Applications

“…Numerous research efforts have been undertaken to modify the structure and function of P3HT materials via synthesis. [8][9][10][11][12][13][14][15][16] For example, the opto-electronic properties of P3HT can be improved by using regiospecific synthetic protocols that eliminate structural defects. 17 18 The coupling of the asymmetric 3-hexylthiophene monomer can result into four different regioisomers ( Fig.…”