MBTA is a sulfur-rich acrylic monomer engineered for high-refractive-index (RI ≥ 1.62 @ 589 nm, 25 °C) UV/LED-curable optical systems.
The benzothiazole–thio-ether conjugation delivers n<sub><sup> ≈ 1.622 while maintaining Abbe number ≈ 26, ideal for thin-film microlenses, AR/VR pancake optics, waveguide claddings, and high-n encapsulants.
Single acrylate functionality provides low shrinkage (< 2 %) and fast surface-through cure with standard Type I photoinitiators (TPO, 1173).
Key Optical & Physical Data:
Refractive index (n<sub><sup>): 1.620 – 1.625
Abbe number (ν<sub>): 26 ± 1
Density: 1.31 g cm⁻³ (20 °C)
Viscosity (25 °C): 85 – 95 mPa·s (easy pumping & coating)
Volume shrinkage on cure: < 2 % (density dilatometry)
**Glass-transition temperature (DSC, 2 % TPO)****: 138 °C
Typical Formulation Use:
High-n lens recipe example:
– 70 wt % MBTA (monomer)
– 28 wt % TMPTA (cross-linker, n = 1.49)
– 2 wt % TPO → UV-LED cure (365 nm, 1 J cm⁻²)
→ Cured film: n = 1.618 @ 589 nm; Tg = 145 °C; yellowness index < 2.
Quality Specification (Optical Grade):
Purity (GC): ≥ 98 %
Colour (Pt-Co): ≤ 50
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 vapour; use gloves, goggles and adequate ventilation. Store in a cool, dry place away from light and oxidants. SDS available on request.
