Improving Dielectric and Mechanical Properties of CaCu3Ti4O12 Nanowire/Epoxy Composites through a Surface-Polymerized Hyperbranched Macromolecule

A core–shell structured organic–inorganic hybrid, that is, a hyperbranched aromatic polyamide (HB-Pa)-coated calcium copper titanate nanowire (CCTO NW), was prepared through a two-step solvent-thermal method followed by in situ polymerization. The morphology and structure of CCTO NWs and HB-Pa-coated CCTO NWs (HB-Pa@CCTO NWs) were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The high dielectric constant composites with notable mechanical properties were fabricated based on the epoxy resin (EP) matrix by using the core–shell structured HB-Pa@CCTO NWs as dielectric filler. At the same mass fraction, the composites filled with HB-Pa@CCTO NWs exhibited more excellent dielectric and mechanical properties than those filled only with synthesized CCTO NWs. At 40 wt % HB-Pa @CCTO NWs content, a relatively high dielectric constant (18) and a low dielectric loss (0.05) at 1 kHz were synchronously obtained. The simultaneous increases in dielectric and mechanical properties resulted from the strengthened interaction between the inorganic ceramic NWs and polymers, thereby resulting in the better dispersion of NWs in the EP matrix.