Synthesis and characterization of polysiloxanes containing carbazolyl and sulfonyl-indole based chromophore as side chains

A new post-functional strategy was developed to prepare polysiloxanes with the sulfonyl-indole based chromophore and carbazolyl side groups. Thus a polysiloxane (P1) with indole and carbazolyl groups as side chains was first synthesized through hydrosilylation reaction, and then the post-azo coupling of p-ethylsulfonylbenzenediazonium fluoroborate toward the indole rings afforded the multifunctional sulfonyl-indole based chromophore-functionalized polysiloxane (P2 and P3). The polymers were easily soluble in common organic solvents, and their maximum absorption appeared at 394 nm, which is about 30 nm blue-shifted compared to the corresponding chromophore with nitro acceptors, and could result in a wider transparency window. The poled films of P2 and P3 reveals a resonant d33 value of 12 and 18 pm/V, respectively, by second harmonic generation (SHG) measurements.