Poly(arylene ether)s with Low Refractive Indices: Poly(biphenylene oxide)s with Trifluoromethyl Pendant Groups via a Meta-Activated Nitro Displacement Reaction

Abstract

High-molecular-weight poly(biphenylene oxide)s (PBPO) were prepared from AB-type monomers, 4′(3′)hydroxy-4-nitro-2,6-bis(trifluoromethyl)biphenyl, through a meta-activated nitro displacement reaction. The displacement of nitro leaving group activated by the two trifluoromethyl groups at the meta-position produced high-molecular-weight polymers, which implies that nucleophilic aromatic substitution reaction of the nitro leaving group proceeded very effectively with two activating groups at the meta-position. The obtained polymers have weight-average molecular weight of 20 800−143 300 g/mol and molecular weight distribution of 1.68−2.85. While two homopolymers of 4′-or 3′-hydroxy-4-nitro-2,6-bis(trifluoromethyl)biphenyl, p-PBPO and m-PBPO, showed a semicrystalline morphology, copolymers of the two monomers were amorphous and dissolved in a wide range of organic solvents. The PBPOs possessed a high glass transition temperature (T g ) in the range of 169 to 208 °C depending on their structure and high thermal stability with 10% weight loss temperatures from 486 to 542 °C in nitrogen and from 465 to 516 °C in air. Moreover, PBPOs containing two trifluoromethyl groups showed low refractive indices in the range of 1.4979−1.5052 as well as low birefringence values of 0.0095−0.0148.

Fluorinated Poly(Arylene Ether)s

“…Kim et al [49] prepared PBPOs containing two -CF 3 groups positioned symmetrically on one phenyl ring from 4 ′ -hydroxy-4-nitro-2,6-bis-(trifluoromethyl)biphenyl and its 3 ′ -isomer through a meta-activated nucleophilic nitro displacement reaction. The effect of the two -CF 3 groups on the reactivity of the meta-activated S N Ar reaction was studied.…”

Postpolymerization of a Fluorinated and Reactive Poly(aryl ether): An Efficient Way To Balance the Solubility and Solvent Resistance of the Polymer

“…Accordingly, many fluorinated PAE have been investigated and developed, of which the PAE containing perfluorophenyl units, −CF 3 groups, and perfluorocyclobutane moieties are particularly gathering attention. 12 −14 These fluorinated PAE exhibit high glass transition temperature (T g ) and excellent optical properties and are expected to be used in areas such as optical communications, ultralarge scale integration circuits, and flat-panel display. 15−19 However, most of the PAE are unsuitable for a solution process because they show low solubility in the common organic solvents.…”

Synthesis of new fluorene-based poly(aryl ether) containing pendant tert-butyl groups for low dielectric materials

“…Another approach to reduce the dielectric constant of aromatic polymers can be realized by incorporation of fluorine atoms or fluorinated groups [11]. These fluorinated polymers usually have better solubility and lower dielectric constant and moisture absorption comparison with the non-fluorinated polymers due to the low polarizability and hydrophobicity of flurine [12][13][14][15][16][17][18]. However, the synthesis and purification of fluorinated monomers are often complicated and difficult.…”