Remarkably high miscibility of octa-substituted POSS with commodity conjugated polymers and molecular fillers for the improvement of homogeneities of polymer matrices

Abstract

This manuscript describes the extremely high affinities of polyhedral oligomeric silsesquioxane (POSS) with conjugated polymers. Polymer films of polyfluorene (PF) and poly(3-hexylthiophene) (P3HT) containing a series of octa-substituted POSS at variable concentrations were prepared. The relationships between the thermal and optical properties of commodity-conjugated polymers and the chemical structures of the substituents in POSS were evaluated by a series of experiments. It was shown that the POSS fillers with relatively longer alkyl substituents can enhance the thermal stabilities of the polymer matrices, even though most of the POSS fillers reduced the decomposition temperatures. The UV−Vis absorption measurements showed that the narrower absorption bands were obtained from the POSS-containing film with PF. It was suggested that the aggregation of the polymer chains could be suppressed by the POSS filler, leading to highly homogeneous states in the films. Moreover, for the P3HT films, the extension of the main-chain conjugation was induced by the POSS fillers with shorter alkyl substituents via the suppression of intermolecular interactions among the polymer chains. These data mean that the POSS fillers can have a significant role in the improvement of the homogeneity in the polymer films due to their high affinity to the conjugated systems. Cubic silsesquioxanes (POSS) with various alkyl substituents were loaded onto commodity-conjugated polymers such as polyfluorene and poly(3-hexylthiophene-2,5-diyl) to investigate structure-property relationships between the substituents of POSS fillers and properties of the polymer films. It was found that the series of POSS fillers can be introduced into conjugated polymer films with high concentrations. Owing to high miscibility, it was demonstrated that POSS can work as a superior molecular filler for realizing homogeneous amorphous films with high thermal stability based on conjugated polymers.