γ-Aminopropyl triethoxysilane functionalized graphene oxide for composites with high dielectric constant and low dielectric loss

A facile and efficient approach was developed to simultaneously functionalize and tune the reduction state of graphene oxide (GO) with γ-aminopropyl triethoxysilane (APTES) aided by NH₃ solution. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy indicated that many surface groups of GO sheets were removed, and APTES were successfully functionalized onto GO sheets. The APTES-functionalized GO sheets (GO-APTES) were dispersed in water and further incorporated into nitrile butadiene rubber (NBR) by latex co-coagulation to form GO-APTES/NBR composites. These composites featured high degrees of exfoliation and intercalation of GO-APTES sheets throughout the NBR matrix. More significantly, the GO-APTES/NBR composites exhibited a relatively high dielectric constant (∼30.8) and a small loss factor (<0.04) at 1.0 kHz, combining with a good insulating property. The unique dielectric responses of GO-APTES/NBR composites open up the potential applications of these materials in resistive and capacitive field grading materials.