Copolymerization of electroactive poly(benzyl ether) dendrimer and terthiophene monomer

In this study, we report the copolymerization, film properties, and HOMO/LUMO levels of the first generation (G1) poly(benzyl ether) dendrimer functionalized on its periphery with terthiophene and terthiophene monomers. Pure G1 dendrimer (DN1), 1:1 and 1:18 molar ratios of the G1 dendrimer and the monomer (e.g., DNTT11 and DNTT118, respectively) are used to compare film formation and HOMO/LUMO levels. The conjugated polymer network (CPN) film obtained from the highest molar ratio of terthiophene monomers shows smooth film formation. Addition of the terthiophene monomer for electrochemical cross-linking controls the surface morphology and the tunability of energy levels of the CPN films. Furthermore, in situ electrochemical quartz crystal microbalance (EQCM) measurements are performed to characterize frequency change (corresponding to mass change) per sweep cycle and relative viscoelastic properties through resonant resistance-resonant frequency (R-F ) diagram during the formation of each CPN film. The DN1 film has relatively higher eleastic film and mass loading on the QCM surface than the copolymeried DNTT11 and DNTT118 films. Furthermore, the addition of terthiophene monomers increases the viscosity of the film due to the effect of introducing linear species on the CNP film formation in solution. Thus, the copolymerization of eletroactive dendrimers with the same electroactive monomers enables control on surface morphological features and energy bandgap for future optoelectronic device applications and physical properties (i.e., viscoelasticity) of the films.