Fluorinated low molecular weight poly(phenylene oxide): Synthesis, characterization, and application in epoxy resin toward improved thermal and dielectric properties

To explore the high performance epoxy resin with high thermal properties and low dielectric constant and loss for copper clad laminates (CCLs), poly(phenylene oxide) (PPO) with low molecular weight is usually used as a modifier. Toward this end, a fluorinated redistributed poly(phenylene oxide) (F-rPPO) with number-average molecular weight of 3.0 ~ 6.2 × 103 g/mol was synthesized via the redistribution reaction of commercial PPO with 4,4′-(hexafluoroisopropylidene) diphenol (BPAF) using benzoyl peroxide (BPO) as an initiator. The structure of F-rPPO was characterized by 1H NMR, 19F NMR and FT-IR, respectively. F-rPPO was employed in the modification of diglycidyl ether of bisphenol A (DGEBA)/methylhexahydrophthalic anhydride (MeHHPA) epoxy resin, and the effect of F-rPPO on the curing behaviors and resulting thermosets were investigated. The results showed that the cured EP/F-rPPO resins exhibited improved thermal and dielectric properties, as well as lower moisture absorption. At 40 phr F-rPPO (based on DGEBA), the cured EP/F-rPPO resin possessed a higher Tg of 146 ℃ and Td5% of 363 ℃ than that of 129 ℃ and 321 ℃ for the pristine epoxy resin, respectively. Moreover, EP/F-rPPO exhibited a lower moisture absorption (0.33%), dielectric constant and loss (2.69 and 0.0132 at 12 GHz) compared to the pristine epoxy resin (0.48%, 2.93 and 0.0303 at 12 GHz, respectively). This work provides an easy and effective solution to fabricate the high performance epoxy resins modified by PPO to better meet the requirement of CCLs.