Low Dielectric Fluorinated Polynorbornene with Good Thermostability and Transparency Derived from a Biobased Allylphenol (Eugenol)

Abstract

A new biobased functional norbornene was synthesized by the Diels–Alder reaction between cyclopentadiene and the fluorinated eugenol. Based on the norbornene monomer, a new polynorbornene was prepared with a high molecular weight (Mn = 78 000 Da) by the standard ring opening metathesis polymerization (ROMP). This polymer displayed good film-forming ability and can be postpolymerized to form a cross-linked network at high temperature (>150 °C) via the [2 + 2] cycloaddition reaction of trifluorovinyl ether (−OCF2═CF2) groups. The cross-linked polymer exhibited good transmittance (T % > 90% at 550 nm) and high thermostability with a 5% weight loss temperature of 412 °C. Moreover, no obvious glass transition temperature (Tg) was observed in the DMA measurement when the temperature was elevated near the decomposition temperature of the cross-linked polymer (about 350 °C). The cured resin displayed an average dielectric constant (Dk) of below 2.65 with average dissipation factor (Df) of 4.3 × 10–3 for the frequencies varying from 40 Hz to 25 MHz. The cross-linked polymer film also possessed good hydrophobicity with a contact angle of 104° (water on the surface of the film) and a surface energy of 26.8 mJ m–2. These data indicate that the combination of norbornene and the fluorinated eugenol can greatly improve properties of polynorbornene, which could have potential application in microelectronic industry. Thus, this contribution may provide a new way for the usage of the biomass.