Colorless polyimide (PI) films with outstanding mechanical and thermal properties are highly demanded in flexible electronics. Herein three 4,4’-diaminodiphenyl ether (ODA)-based diamines with different substitutions (-CH3, -CF3) and substitution...

A series of hyperbranched polysiloxane (HBPSi)‐based hyperbranched polyimide (HBPI) films with low dielectric permittivity and multiple branched structures are fabricated by copolymerizing 2,4,6‐triaminopyrimidine (TAP) with 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐diaminodiphenyl ether, and HBPSi via the two‐step polymerization method. The dielectric permittivity of HBPSi hyperbranched polyimide films decreases with increasing TAP fraction, namely, from 3.28 for sample PI‐1 to 2.80 for PI‐4, mainly owing to the enlarged free volume created by the incorporation of multiple branched structures. Moreover, HBPSi HBPI possesses desirable solubility and good mechanical properties and thermal stability. PI‐4 not only has low dielectric permittivity (2.80, 1 MHz), excellent solubility (soluble in several common organic solvents), and remarkable thermal properties (glass‐transition temperature of 273 °C, 5% weight loss temperature of 498 °C in N2 and 486 °C in O2), but it also demonstrates admirable mechanical properties with a tensile strength of 103 MPa, elongation at break of 7.3%, and a tensile modulus of 2.16 GPa. HBPSi HBPI might have potential applications in interlayer dielectrics and other microelectronics fields. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47771.

No 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.