New poly(amide-imide)s with trifluoromethyl and chloride substituents: Synthesis, thermal, dielectric, and optical properties

3 years ago

New poly(amide-imide)s with trifluoromethyl and chloride substituents: Synthesis, thermal, dielectric, and optical properties

Two novel fluorinated diimide-diacid monomers, [2,2′-(4,4′-(4′-chloro-3′-(trifluoromethyl)biphenyl-2,5-diyl)bis(oxy)bis(3-(trifluoromethyl)-4,1-phenylene))bis(1,3-dioxoisoindoline-5-carboxylic acid)] (III) and [2,2′-(4,4′-(3′,5′-bis(trifluoromethyl)biphenyl-2,5-diyl)bis(oxy)bis(3-(trifluoromethyl)-4,1-phe-nylene))bis(1,3-dioxoisoindoline-5-carboxylic acid)] (IV), were respectively designed and synthesized viathe reactions between the diamine (I or II) and two molar equivalents of trimellitic anhydride. Based on these two diimide-diacids, two families of novel poly(amide-imide)s (PAIs) (IIIa–IIIe and IVa–IVe) bearing different trifluoromethyl groups were prepared by directly polymerizing diimide-diacids with a series of aromatic diamines (a–e). All of the PAIs exhibited high glass transition temperatures (T gs, 236–268°C), excellent thermal stability (only 5% weight loss at 493–542°C under nitrogen) and good solubility in various organic solvents since the bulky pendant groups were introduced. The cast films of these PAIs (thickness=80–90μm) had excellent optical transparency (70–83% at 450nm, 85–87% at 550nm and 88–89% at 800nm) and low dielectric constants (2.62–2.92 at 1MHz). In addition, the spin-coated films of these PAIs presented very low birefringence values the minimum of which was 0.0073 at 650nm. These spin-coated films also exhibited very weak absorption at the near-infrared communication wavelengths of 1310 and 1550nm.

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DOI: S0014305717308832