Synergistic Effect of Sulfur and Chalcogen Atoms on the Enhanced Refractive Indices of Polyimides in the Visible and Near-Infrared Regions

Abstract

To develop thermally stable optical polymers for visible and near-infrared sensor applications, a series of sulfur-containing polyimides (PIs) with chalcogen atoms were successfully synthesized via conventional two-step polycondensation of 4,4′-[p-thiobis­(phenylene­sulfanyl)]­diphthalic anhydride (3SDEA) with four diamines: 4,4′-oxidianiline (ODA), 4,4′-thiodianiline (TDA), 4,4′-selenodianiline (SEDA), and 4,4′-tellurodianiline (TEDA). Because of the large atomic polarizabilities of the sulfur, selenium, and tellurium atoms, the resultant PIs exhibited significantly high refractive indices in the 1.738–1.778 range at 637 nm along with a transmittance >90% at 650–1500 nm. In addition, the PIs exhibited good thermal stability, with high thermal decomposition and glass transition temperatures (T d5% > 390 °C and T g = 183–217 °C, respectively). Owing to the good affinity of SEDA–3SDEA for TiO2 nanoparticles, a nanocomposite film with a 3.0 wt % loading of TiO2 nanoparticles exhibited a refractive index of 1.774 at 637 nm.

Organoselenium chemistry-based polymer synthesis

“…This will be used as a potential RI responsive redox sensor. In addition to Zhu's works, You et al reported selenide-containing PIs that can enhance the refractive indices in the visible and near-infrared regions (Scheme 4D), 53 and they exhibited a refractive index of 1.778 at 637 nm. Recently, Tang and his coworkers synthesized selenium-containing polymers using a multicomponent polymerization which shows high efficiency, requires mild reaction conditions and is atom economical, 163,164 where thin films fabricated by spin-coating exhibited high refractive indices of up to 1.806 at 550.0 nm.…”

“…In addition to Zhu's work, You et al reported selenide-containing PIs that can enhance the refractive indices in the visible and near-infrared regions (Scheme 4D). 53 These works indicate that the introduction of chalcogen atoms in the polyimide backbone is a promising method for improving the refractive index of thermally stable optical materials, specifi- cally those employed in advanced sensor and imaging applications.…”

Visual Ozone Sensor: Structural Color Change of Pendant Selenium‐Containing Maleimide Polymers via Oxidation

“…Selenium‐containing polymers (Se‐polymers) have been demonstrated to be suitable candidates for the fabrication of high‐refractive‐index materials (HRIMs) in the past 10 years [ 1–7 ] due to the high molar refractive index (RI) of selenium‐containing moieties. These HRIMs are promising for use in plastic lenses, advanced display devices, encapsulants for organic light‐emitting diodes, diffractive gratings, and antireflective coatings.…”

Synthesis of colorless and high-refractive-index sulfoxide-containing polymers by the oxidation of poly(phenylene sulfide) derivatives

“…High refractive index polymers (HRIPs) have attracted much attention in the field of various optical devices, owing to their flexibility, light weight, and high light extraction efficiency. 1,2 The refractive index (RI, n) of a polymer is quantitatively determined using the Lorentz-Lorenz equation, which explains that atomic groups with high molar refraction ([R]) and low molecular volume (V) afford HRIPs; sulfur, [3][4][5] aromatics, 6,7 and heavy chalcogenides [8][9][10] are frequently introduced in the repeating units of HRIPs. Our group found that poly(phenylene sulfide) (PPS), regarded as one of the super engineering plastics with high crystallinity and thermal stability, became completely amorphous once it was derivatized with alkyl or alkoxyl side groups.…”