3D\nPrinted Carbon\nNanotube/Phenolic Composites for\nThermal Dissipation and Electromagnetic Interference Shielding

Here we demonstrate\ndirect ink write (DIW) additive manufacturing\nof carbon nanotube (CNT)/phenolic composites with heat dissipation\nand excellent electromagnetic interference (EMI) shielding capabilities\nwithout curing-induced deformation. Such polymer composites are valuable\nfor protecting electronic devices from overheating and electromagnetic\ninterference. CNTs were used as a multifunctional nanofiller to improve\nelectrical and thermal conductivity, printability, stability during\ncuring, and EMI shielding performance of CNT/phenolic composites.\nDifferent CNT loadings, curing conditions, substrate types, and sample\nsizes were explored to minimize the negative effects of the byproducts\nreleased from the cross-linking reactions of phenolic on the printed\nshape integrity. At a CNT loading of 10 wt %, a slow curing cycle\nenables us to cure printed thin-walled CNT/phenolic composites with\nhighly dense structures; such structures are impossible without a\nfiller. Moreover, the electrical conductivity of the printed 10 wt\n% CNT/phenolic composites increased by orders of magnitude due to\nCNT percolation, while an improvement of 92% in thermal conductivity\nwas achieved over the neat phenolic. EMI shielding effectiveness of\nthe printed CNT/phenolic composites reaches 41.6 dB at the same CNT\nloading, offering a shielding efficiency of 99.99%. The results indicate\nthat high CNT loading, a slow curing cycle, flexible substrates, and\none thin sample dimension are the key factors to produce high-performance\n3D-printed CNT/phenolic composites to address the overheating and\nEMI issues of modern electronic devices.