A novel preservative film was prepared by blending konjac glucomarman (KGM) and poly (diallydi-methylammonium chloride) (PDADMAC) in aqueous system. The effects of PDADMAC content on the miscibility, morphology, thermal stability, and mechanical properties of the blend films were investigated by density detern-Lination, scanning electron microscopy (SEM), attenuated total reflection infrared spectroscopy (ATR-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile tests. The results of the density determination predicted that the blends of KGM and PDADMAC were miscible when the PDADMAC content was less than 70 wt%. Moreover, SEM and XRD confirmed the result. ATR-IR showed that strong intermolecular hydrogen bonds interaction occurred between the negative charge groups of KGM and the quaternary ammonium groups of PDADMAC in the blends. The tensile strength and the break elongation of the blends were improved largely to 106.5 MPa and 32.04%, when the PDADMAC content was 20 wt %. The thermal stability of the blends was higher than pure KGM. Results from the film-coating preservation experiments with lichi and grapes showed that the blend film had excellent water-holding and preservative ability. (c) 2007 Wiley Periodicals, Inc.