This tetra-sulfur heterocyclic di-thiol is engineered as a high-refractive-index building block (n<sub><sup> ≈ 1.60) for radical or thiol-ene photopolymerisation.
Two primary –SH groups provide quantitative thiol-ene/-yne or epoxy-thiol addition, giving high cross-link density without yellowing.
The rigid 1,4-dithiane ring minimises volume shrinkage (< 2 %) while maintaining Abbe number ≈ 28, suitable for thin-film microlens, waveguide cladding, AR/VR pancake lenses, and high-n encapsulants.
Key Optical & Physical Data:
Refractive index (n<sub><sup>): 1.598 – 1.603
Abbe number (ν<sub>): 28 ± 1
Density: 1.21 g cm⁻³ (20 °C)
Melting point: 48 – 52 °C (process-friendly melt-casting)
Viscosity (80 °C): 18 – 22 mPa·s (low melt-viscosity for precision moulding)
Volume shrinkage on cure: < 2 % (measured by density dilatometry)
Glass-transition temperature (DSC, 3 % DPDS cross-linker): 135 °C
Typical Formulation Use:
Thiol-ene lens recipe example:
– 60 wt % 136122-15-1 (di-thiol)
– 38 wt % divinyl-siloxane (n = 1.56)
– 2 wt % TPO-L → UV-LED cure (365 nm, 1 J cm⁻²)
→ Cured film: n = 1.624 @ 589 nm; Tg = 142 °C; yellowness index < 2.
Quality Specification (Optical Grade):
Purity (GC): ≥ 98 %
Colour (Gardner): ≤ 1
Water content (KF): ≤ 0.1 %
Metal ions (ICP-OES): Na⁺, K⁺, Ca²⁺, Fe³⁺ each ≤ 0.5 ppm
Transmittance (400 nm, 1 cm cell): ≥ 95 %
Hazard Statement:
Causes skin and eye irritation (H315 + H319); harmful if swallowed (H302). Avoid inhalation of dust; use gloves, goggles and adequate ventilation. Store in a cool, dry place away from oxidants and light. SDS available on request.
