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
2,5-Bis(mercaptomethyl)-1,4-dithiane
Cas:136122-15-1
Purity: ≥ 98 % (GC)
Refractive Index：1.60
Molecular Formula: C₆H₁₂S₄
Molecular Weight: 212.42 g mol⁻¹
Appearance: Colourless to pale-yellow low-melting solid; mild sulfurous odour.
