High‐refractive index polythiourethane resin based on 2,3‐bis((2‐mercaptoethyl) thio)‐1‐propanethiol and 1,3‐bis(isocyanantomethyl) cyclohexane using tertiary amine catalyst

Abstract

High‐refractive index (RI) polythiourethane (PTU) resin with good thermal, optical, and mechanical properties was synthesized via thiol‐isocynanate click reaction of 2,3‐bis((2‐mercaptoethyl)thio)‐1‐propanethiol and 1,3‐bis(isocyanantomethyl) cyclohexane using a new tertiary amine catalyst N,N,N′,N′‐tetramethyl‐1,4‐diaminobutane (TMDB). Curing behavior of PTU resin was studied by dynamic differential scanning calorimetry (DSC) technique. Curing technology parameters were optimized by combined use of DSC and fourier transform infrared spectrometry (FTIR). The results indicate that TMDB exhibits higher catalytic activity than commonly used dibutyltin dichloride (DBTC). The Kissinger apparent activation energies at a dosage of 150 ppm TMDB and 150 ppm DBTC are 31.7 and 43.2 kJ mol−1, respectively. PTU resin with a full conversion of thiol and isocynanate was prepared, which exhibited better thermal, optical, and mechanical properties than that reported previously. The resin displays a glass transition temperature of 102 and 129°C determined by DSC and dynamic thermomechanical analysis (DMA), respectively, a 5% weight loss temperature of 279°C in nitrogen, a light transmittance of 87% in the wavelength range of 410–900 nm, a water contact angle of 100°, a high‐RI of 1.617, and an Abbe number of 38. The resin was successfully applied in ophthalmic lenses.

Chemistry of Polythiols and Their Industrial Applications

“…Depending on the characteristic of the catalyst used, the activation occurs in two ways. If a basic catalyst is used, it activates the thiol by forming a nucleophilic activated anion, a species that attacks the isocyanate carbon [ 157 ]. If a Lewis acid is used as a catalyst, the coordination occurs with an isolated pair of oxygen or nitrogen (electrophilic activation) of the isocyanate that can be attacked by less nucleophilic substances, such as neutral thiols [ 154 , 158 ].…”

High Refractive Index Diphenyl Sulfide Photopolymers for Solar Cell Antireflection Coatings

“…High refractive index photopolymers (HRIPs) are high refractive index polymers (n > 1.5) that can be quickly cured under ultraviolet light (UV) irradiation [6]. This polymer has been widely investigated for potential application in the field of advanced optical device manufacturing, such as lenses [7], optical adhesives [8], holographic lenses [9], intraocular lenses [10], anti-reflective coatings [11], and LED packaging materials [12,13]. The refractive index affects the propagation path of light; the higher the refractive index, the thinner the material can be [14].…”

Zirconium dioxide@phosphazene for enhancing mechanical property, flame retardancy, and thermal property of polythiourethane composites

“…Unlike polyurethane, PTU is created by crosslinking of mercapto‐containing thiols with isocyanates 5,6 . It has many ideal characteristics, such as intrinsic high refractive index, good solvent resistance, superior mechanical properties, simple curing and processing, which makes it widely used in the field of optoelectronics and engineering construction materials 7–13 . However, although PTU has slightly good flame retardancy imparted by sulfur atoms and relatively high mechanical strength endowed by dense cross‐linked structures, further improvements are needed to meet the requirements of high‐performance materials applications.…”