Constructing a special interface structure of starch/PBAT composites with a novel “many-to-many” strategy

It is a challenge to achieve a high reaction ratio of compatibilizers for improving the compatibility of the composites due to high melt viscosity and short residence time during melt processing. Inspired by the fact that xanthium seeds in nature are easy to combine with animal fur efficiently, a new "many-to-many" melting chemical reaction strategy was proposed to greatly improve the reaction ratio of compatibilizers. In this work, a polycaprolactone-based polyurethane prepolymer (PCLPU) was used to prepare compatible starch/poly(butyleneadipate-co-terephthalate) (PBAT) composites. Polyurethane nanoparticles containing a lot of -NCO groups were prepared and then reacted with tapioca starch with a lot of -OH groups in an intensive mixer to obtain starch/PBAT composite material with a special interface structure. Compared with the biocomposites without PCLPU, the PCLPU-modified biocomposites exhibited compatible morphology and excellent mechanical properties, and the reaction ratio of the PCLPU was as high as 99.2%. The special polyurethane prepolymer interface formed in the composite interacted with the hydrophilic starch granules through urethane linkages and with hydrophobic PBAT through physical PBAT-PBAT linkages. Therefore, the novel strategy used to achieve a special interface structure for improving the mechanical properties of a composite was a simple, efficient, and environmentally friendly method.