Fluorinated bismaleimide resin with good processability, high toughness, and outstanding dielectric properties

In this study, novel fluorinated bismaleimide (BMI) resins were prepared by the copolymerization of 2,2-bis[4-(4-maleimidephenoxy)phenyl]hexafluoropropane (6FBMP) and diallyl hexafluorobisphenol A (6FDABPA) to enhance their dielectric properties. The dielectric properties of the resins were investigated in the frequency range 7-18 GHz through a cavity method. Through the incorporation of a hexafluoroisopropyl group with the polymer chain, the dielectric constant (epsilon) was effectively decreased because of the small dipole and the low polarizability of the carbon-fluorine (CF) bonds. The 6FBMP/6FDABPA resin possessed excellent dielectric properties, with epsilon being 2.88 and the dielectric loss being 0.009 at 10 GHz and 25 degrees C. In comparison with the 4,4-bismaleimidodiphenylmethane (BDM)/2,2-diallyl bisphenol A (DABPA) resin, the glass-transition temperature (T-g) of 6FBMP/6FDABPA decreased. The flexible ether group in the long chain of 6FBMP was considered to disrupt chain packing and cause a decreased crosslinking density and a lower T-g. 6FBMP/6FDABPA showed a similar thermal decomposition temperature and good thermal properties like the BDM/DABPA resin, whereas the impact strength of the 6FBMP/6FDABPA resin was almost 1.6 times higher than that of the BDM/DABPA resin. (c) 2015 Wiley Periodicals, Inc.