Processable Inverse-Vulcanized Polymers With Silicon-Like High Refractive Index and Transmittance for Infrared Optics

Area of Science:

• Materials Science
• Polymer Chemistry
• Optical Engineering

Background:

• Inverse vulcanization produces polymers superior to traditional organic materials for infrared optics.
• Achieving high refractive index and infrared transparency in all-organic polymers remains a challenge compared to inorganic materials.

Purpose of the Study:

• To develop all-organic polymers with enhanced refractive index and infrared transparency.
• To explore the use of sulfur-rich monomers in inverse vulcanization for optical applications.

Main Methods:

• Synthesized poly(S-TTF) polymers via inverse vulcanization of tetrathiafulvalene (TTF) with controlled sulfur feeding ratios.
• Investigated the optical properties, including refractive index and infrared transmittance, of the resulting polymers.

Main Results:

• Poly(S-TTF) exhibited increased infrared refraction and transmission due to high polarizability, multiple reaction sites, and high symmetry.
• Poly(S60-TTF) (88wt% sulfur) demonstrated a tunable refractive index (~3.0) and >60% transmittance in near/mid-infrared.
• Achieved <2% visible light transmittance and >90% near-infrared transmittance for 5µm poly(S60-TTF) films.

Conclusions:

• Developed organic copolymers with competitive refractive index and excellent infrared transmittance, surpassing inorganic materials for imaging and security.
• The strategy provides a valuable reference for tuning optical properties of inverse-vulcanized polymers using sulfur-ultrarich monomers.