Fabrication of uniform vertically-aligned carbon nanotube–polymer composite thin films by capillary flow intrusion

Polymer and nanomaterial composites, known as nanocomposites, are advanced materials that have many potential applications. One type of thin-film nanocomposite is a polymer–carbon nanotube (CNT) nanocomposite, whose properties are strongly dependent on the uniformity and alignment of CNTs in the nanocomposite. However, the control of CNT alignment in these nanocomposites is still difficult to achieve. Here, we propose a facile single-step method, a capillary flow intrusion method, to fabricate uniform polymer nanocomposite thin films of vertically aligned (VA) single-/multi-walled CNTs that range from 15 to 300 µm in thickness. Raman scattering spectroscopy and polarized Raman spectroscopy measurements, and cross-sectional scanning electron microscopy (SEM) observations confirmed that the polymer was uniformly infiltrated into VACNTs, such that the alignment of CNTs in the nanocomposite was preserved and there were no excess portions of the polymer. Experimental and numerical calculation results indicated that capillary flow rate, wettability, and polymer shrinkage are important factors in the capillary flow intrusion method.