Highly Refractive Polyimides Derived from Efficient Catalyst-Free Thiol–Yne Click Polymerization

Abstract

Polyimides (PIs), owing to their inherent high refractive index and excellent physical properties, are required in advanced optical applications. They are traditionally synthesized through conventional two-step polycondensation, followed by hightemperature or chemical imidization, inevitably increasing energy consumption, environmental pollution, and production duration. Herein, for the first time, we synthesized PIs consisting of vinylene sulfide linkages via an efficient catalyst-free thiol−yne click polymerization, which would be accomplished within 2 h at 25 °C by simply mixing the dithiols and bisimide-containing diynes in THF, affording PIs with tensile strength ranging from 106.3 to 114.9 MPa, glass transition temperature up to 238 °C, thermal decomposition temperature as high as 381 °C, and desirable solubility, so that it was easily cast from solution into tough films. Moreover, the BPADA-TBT PI film demonstrates good optical performance, with its refractive index exceeding 1.70 at 633 nm and transmittance above 81% at 450 nm, making it a potential candidate in advanced optical applications.

A Strategy of Thiolactone Chemistry to Construct Strong and Tough Self-Healing Supramolecular Polyurethane Elastomers via Hierarchical Hydrogen Bonds and Coordination Bonds

“…Thiolactone is a five-membered cyclic sulfur compound, which can be opened by a primary amine in the absence of catalysts and simultaneously release a thiol in situ . The exposed thiols are subsequently captured through thiol-ene/yne, thiol-acrylate, thiol-epoxy, and thiol-isocyanate reactions to achieve a one-pot two-step double functionalization. − Given the advantages of simplicity, high efficiency, and no byproducts of this strategy, thiolactone chemistry provides an effective platform for side-chain modification of the polymers.…”

X-Yne Click Polymerization

“…For instance, unlike conventional two-step polycondensation, Zhang et al creatively synthesized the functional polyimides (PIs) with good optical properties and robust mechanical properties by spontaneous thiol-yne click polymerization (Figure 1C). 29 The resultant PIs showed good tensile strengths as high as 114.9 MPa, high glass transition temperatures and thermal decomposition temperatures (up to 238 o C and 381 o C, respectively). Notably, one of the prepared polymer films, PI BPADA-TBT, demonstrated a comparable or even preferable refractive index and much lower birefringence than most of the previously reported PIs.…”

“…The introduction of sulfur atoms effectively raised the refractive index of polymers, making thiol-yne click polymerization promising for optical applications. 29 It's found that both vinyl ether bond and enamine bond are labile under weak acidic conditions, 44,59 and in addition, the enamine bond has an exceptional 1 O2responsiveness. 61 These unique characteristics make the corresponding polymers inherently degradable in the presence of weak acid or 1 O2 and has led to the widespread applications of hydroxyl/amino-yne click polymerizations in the construction of controlled release drug carriers.…”

Polyimide Hybrid Nanocomposites with Controlled Polymer Filling and Polymer–Matrix Interaction

“…Selecting a functional polymer as the polymer phase, such as a polyimide with excellent thermal and chemical resistance, , can introduce new functionalities to the hybrid nanocomposite. Previously, we fabricated polyimide nanocomposites exhibiting a combination of low-density as well as heat and fracture resistance that was useful for lightweight and high-temperature applications .…”