Polyamide 6 (PA6) and PA6/octaammonium POSS (OA-POSS) nanocomposites were synthesized by phase inversion procedure assisted with external electric field and characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle (CA) measurements. It is very interesting to find that external electric field has greatly different effects on the microstructure evolution behaviors of PA6 and PA6/OA-POSS nanocomposites. For pure PA6 samples, crystallization was retarded while hydrophilicity was enhanced with increasing the strength of applied electric field. However, for PA6/OA-POSS nanocomposites, both crystallinity and hydrophilicity keep stable with increased electric field strength. The migration behavior of OA-POSS molecules was hindered under electric field. The mechanism for the formation of PA6 and PA6/OA-POSS nanocomposites with the presence of external electric field is discussed. (C) 2015 Elsevier B.V. All rights reserved.