Further investigation of conjugated length and dispersity on light‐driven hydrogen evolution facilitated by conjugated polymers

Abstract

Conjugated length and dispersity are modulated by the incorporation of nonconjugated groups. The integration of 1,4-butanediylbis(oxy) groups into poly[(1,-4-benzo{2,1,3}thiadiazole)-co-1,4-benzene] gives numerous co-polymers. The presence of the 1,4-butanediylbis(oxy) unit in the polymer backbone interrupts the conjugation length. The optical energy gap is not much affected. The variation in the hydrogen evolution rate (HER) is evident. Density-functional-theory calculations suggest that the distribution of residual Pd along the polymer chain could be influenced considerably by the introduction of 1,4-butanediylbis(oxy) group, accounting for the variation in the HER. On the other hand, a macromonomer with oligo tert-butyl acrylate side chains synthesized through atom transfer radical polymerization is copolymerized with 3,7-dibromo-dibenzothiophene 5,5-dioxide to furnish a random copolymer. The ester groups in the polymer can be transformed to the acid moieties. The polymer with the acid functionality exhibits superior dispersity in the reaction solvents. Nonetheless, the difference in the hydrogenevolution activity is marginal between the two polymers, revealing that the increase in the polymer dispersity does not essentially improve the photoactivity for this reaction. These studies reveal that a structural variation could simultaneously lead to the alternation in numerous properties. Emphasis on a particular property could be misleading in designing active photocatalysts in hydrogen evolution.