Soy protein-based nanocomposites reinforced by supramolecular nanoplatelets assembled from Pluronic polymers/beta-cyclodextrin pseudopolyrotaxanes

摘要

The self-assembled rigid supramolecular nanoplatelets (SN) from Pluronic polymers with various lengths of polyethylene oxide (PEO) and beta-cyclodextrin have reinforced the soy protein isolate (SPI)-based biodegradable plastics in terms of strength and modulus but at the expense of elongation. Meanwhile, the water resistance, which limited the application of the SPI plastics, was also enhanced. The structure and properties of nanocomposites were characterized by X-ray diffraction, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile test, and water uptake test. The low loading of nanoplatelets was able to disperse into SPI matrix homogeneously, which resulted in reinforcement in nanocomposites. With an increase of nanoplatelets loading, the repulsion between nanoplatelets and SPI matrix occurred, accompanying with the formation of rectangle objects, resulted in a decrease of mechanical performance of the nanocomposites. The nanoplatelets with longest free PEO segments produced highest strength with least loss of elongation by virtue of enhanced association with SPI matrix mediated by PEO segments. Meanwhile, the nanoplatelets with moderate length of free PEO segments showed optimal water resistance. Herein, the reinforcing function of a supramolecular nanoplatelet, similar to the structure of layered silicate, was verified. (C) 2007 Government of Canada. Exclusive worldwide publication rights in the article have been transferred to Wiley Periodicals, Inc.