Dextrin is widely used in the food, biomedical, and cosmetic industries. In this work, a new ethanolic fractionation method, the multiple ethanolicprecipitation (MEP), is established to fractionate the acid-hydrolyzed waxy corn starch (AHWCS) that consists of a high concentration of low-molecularweight dextrin. Through these multiple precipitation processes, the effect of the dextrin concentration on fractionation is weakened, which makes the fractionation only dependant on the molecular weight of dextrin. Five dextrin fractions (P 1 , P 2 , P 3 , P 4 , and P 5) with narrow molecular weight distributions are obtained. The weight-average molar mass (M w) and the molecular weight dispersity (D) of five fractions are 7.3 × 10 4 g mol −1 (2.0), 2.3 × 10 4 g mol −1 (2.1), 1.6 × 10 4 g mol −1 (2.2), 8.9 × 10 3 g mol −1 (2.1), and 4.5 × 10 3 g mol −1 (3.3), respectively. Additionally, the increase of molecular weight tends to decrease the moisture-absorption but increase the viscosity and thermal stability, which can provide a basis for the application of different molecular weight dextrin fractions in different fields. These results suggest that the MEP method is a low cost and efficient approach for directly separating dextrin fractions with narrow molecular weight distributions from the AHWCS.

Composite films composed of biocompatible polymers are used widely in biomedical and food packaging areas. In this work, a new composite film with superior mechanical properties and biodegradability is prepared. The film is composed of biocompatible polyhydroxyethyl acrylate (PHEA) and starch, whose molecular chains are cross‐linked using sucrose polyaldehyde (SPA), a green sucrose derivative. The composite film exhibits an optimal tensile strength and tensile strain of 11.5 MPa and 147.7%, respectively, which can be ascribed to the chemical cross‐linking and hydrogen bond interactions between PHEA and starch. The tests confirm that the composite film shows satisfactory mechanical properties, hydrophilicity, and biodegradability, and thus should have wide applicability in biomedicine, food packaging, and other fields.