Effect of Amino Acid Ionic Liquids on the Interfacial Structure and Degradation Behavior of PLA/PBAT Blends

The lysine p-toluenesulfonic acid ionic liquid ([Lys][p-TSA]), one kinds of amino acid ionic liquids, was synthesized by one-step method, which was employed to control the interfacial structure and degradation behavior of poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends. The [Lys][p-TSA] was incorporated into PLA/PBAT blends with different contents by melt blending, and the effect of [Lys][P-TSA] on the interfacial structure, thermal stability, crystallization behavior, rheological behavior and degradation behavior of PLA/PBAT blends were investigated. The SEM results demonstrate that [Lys][p-TSA] could enhance the compatibility between PLA and PBAT in the PLA/PBAT blends. Thermal gravimetric results showed that the incorporation of [Lys][p-TSA] into PLA/PBAT blends could not affect their thermal stability. Differential scanning calorimetry (DSC) measurements showed that [Lys][p-TSA] can improve the crystallinity of PLA, and the rheological behavior of the blends indicated that [Lys][p-TSA] can enhance the chain mobility of PLA and PBAT. More importantly, the degradation behavior of the blends revealed that [Lys][p-TSA] could affect the distribution of lipase in PLA/PBAT blends, so that the relative degradation rate of each component of the blends was well-controlled. As the [Lys][p-TSA] content increased, the degradation rate of the PLA/PBAT blend in phosphate buffered saline (PBS) solution, artificial seawater, porcine pancreas lipase (PPL) solution and Candida antarctica lipase B (CALB) solution was enhanced. When the contents of [Lys][p-TSA] was 4 phr in the PLA/PBAT blend, the weight loss of the blend in PPL enzyme solution reached to 31.59