Synthesis, mechanical properties and biodegradation of various acrylic acid-grafted poly(butylene succinate-co-terephthalate)/organically modified layered zinc phenylphosphonate nanocomposites

Abstract

A new series of biodegradable aliphatic-aromatic nanocomposites containing various acrylic acid-grafted poly(butylene succinate-co-terephthalate) (PBST) and organically modified layered zinc phenylphosphonate (m-PPZn) were successfully synthesized through the transesterification and polycondensation having the covalent linkages between polymer and inorganic materials. Fourier transform infrared (FTIR) and 13C-nuclear magnetic resonance (NMR) spectra demonstrate the successful grafting of acrylic acid to PBST (g-PBST). Both wide-angle X-ray diffraction and transmission electron microscopy data show that the g-PBST polymer matrix was intercalated into the interlayer spacing of m-PPZn. The additional m-PPZn into g-PBST matrix significantly enhanced the storage modulus as compared with that of neat g-PBST. The reduction in thermal stability was observed in all g-PBST/m-PPZn systems, which is probably caused by more nucleation to form more tiny and imperfect crystals. The biodegradations of neat g-PBST copolymers and g-PBST/m-PPZn nanocomposites were investigated using lipase from Pseudomonas sp. The degradation rates of the neat g-PBST copolymers increased in the order of g-PBST-70 > g-PBST-50 > g-PBST-30. The faster degradation rate of g-PBST-70 is a result of a higher content of succinic acid unit and chain flexibility of polymer backbone. Furthermore, the weight loss increased by increasing the loading of m-PPZn, suggesting that the existence of m-PPZn improved the degradation of the g-PBST copolymers.