A series of novel sulfur containing high refractive index linear and branched poly­(arylene thioether)­s and linear poly­(arylene ether)­s were synthesized via nucleophilic substitution reactions. The sulfur content was varied in each polymer structure, and the physico-chemical properties of the polymer were investigated with respect to sulfur and aromatic content. The polymers prepared exhibited transparency as high as 90% in the visible region and an RI of more than 1.70 at 589 nm. These properties along with high thermal stability (T d5% up to 530 °C), excellent mechanical properties with tensile strength as high as 63 MPa and Young’s modulus being 2.33 GPa, and ease of processability into thin films make the prepared series of polymers good candidates to be successfully applied in opto-electronic devices.

Three series of sulfur-containing polyimides with the bis(3-(trifluoromethyl)phenyl)thiophene moiety were reported. The synthesis of high-refractive-index polyimides was carried out using a nucleophilic substitution reaction. For that, two new sulfur-containing aromatic amino monomers were developed, one bifunctional and one trifunctional. The monomer and polymer structures were successfully characterized by NMR and Fourier transform infrared (FTIR) spectroscopic methods. Free-standing polyimide films of ∼10 μm were prepared, and they were found to have high thermodynamic stability with T g as high as 257 °C and T d5% above 500 °C. The films were flexible as well as tough with up to 16 ± 7% elongation at break, with a Young’s modulus of 2.6 ± 5 GPa. Indication for melt processability of one of the polyimides was also demonstrated at a temperature of 30 °C above its T g. Thin films with thickness in the nanometer range were coated over modified Si-wafers. Increase in the sulfur and aromatic contents in the polymer backbone resulted in the increase of their refractive index; thus, the polymers synthesized in this work exhibited refractive index as high as 1.76 at 589 nm. The transmittance and birefringence of the polyimides were found to improve by modification in the chemical structure. The tuneable optical properties and good dynamic stability of the polyimides make them potential candidates in optoelectronic applications.

The synthesis of solution‐processable sulfur‐containing polytriazoles for optoelectronic applications is a relatively less explored domain in polymer research. The synthesis of novel bifunctional (DA) and trifunctional (TA) azido‐monomers with inherent high sulfur content and of organo‐soluble high refractive index poly(1,2,3‐triazole)s using the azido‐monomers via Cu(I) assisted click polymerization reactions are reported in this work. The azido‐monomers were synthesized by the conversion of previously reported amine‐functionalized compounds to azides using azidotrimethylsilane in a polar aprotic solvent. Dialkyne monomers were also synthesized and reacted with the azides to prepare a series of five linear and two hyperbranched poly(1,2,3‐triazole)s. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry and thermogravimetric analysis were used to characterize the synthesized polymers. It was also demonstrated that the use of the trifunctional azide in optimized conditions resulted in increased solubility of an otherwise insoluble linear poly(1,2,3‐triazole). The optical characterization of the polymers was carried out on thin polymer films with thickness in the nanometer range, which were successfully prepared by spin‐coating on silicon wafers. It was found that the increase in the sulfur and aromatic content in the polymer backbone successfully increased the refractive index of the polymers up to 1.743 at 589 nm.