Soluble N-Substituted Organosilane Polybenzimidazoles

Six N-substituted polybenzimidazole organosilane derivatives (−CH2SiMe2R; R = methyl, vinyl, allyl, hexyl, phenyl, and decyl) were synthesized, and they are more soluble in common organic solvents (tetrahydrofuran and chloroform) than the parent polybenzimidazole. Our polymer modification pathway provides a straightforward synthesis that can be carried out at room temperature/pressure and give moderate yields. Solution 1H NMR spectra of both the parent and deprotonated polybenzimidazoles are reported. On the basis of the NMR analysis in CDCl3, nearly all of the benzimidazole N−H positions (two ligands per repeat unit) are substituted by the organosilane moieties. Some of the modified polymers have comparable thermal properties to the parent polymer, and the average molecular weights are higher for the substituted polybenzimidazoles than the parent PBI.