Nanoplastics were prepared using the formamide/ethanolamine-plasticized thermoplastic starch (FETPS) as the matrix and ethanolamine-activated montmorillonite (EMMT) as the reinforcing phase. Wide angle X-ray diffraction (WAXD), scanning electron microscope (SEM) and transmission electron microscope (TEM) revealed that FETPS was successfully intercalated into the layers of EMMT and formed the intercalated nanoplastics with EMMT. When EMMT content was 5 wt%, the mechanical testing indicated that the tensile stress of the nanoplastics achieved 7.5 MPa, and the tensile strain achieved 85.2%, Young's modulus increased from 47.2 MPa of pure FETPS to 145.1 MPa of FETPS/EMMT nanoplastics, and the breaking energy increased from 1.34 to 1.81 N to after being stored at RH = 25% for 14 days. Comparing with FETPS, the nanoplastics effectively restrained the recrystallization of starch. In contrast to pure FETPS, the strength of nanoplastics obviously improved, and the thermal stability and water resistance also improved. (c) 2005 Elsevier Ltd. All rights reserved.