Novel miscible blends of biodegradable polymer and biocompatible polyphenol acquired from natural source

Abstract

A novel miscible blend of all compositions comprising biodegradable poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] and biocompatible tannic acid (TA) was discovered and investigated. Studies of the present work were mainly performed to discuss the miscibility and interactions of the blends. The TA/P(BA-co-BT) blends exhibit a single composition-dependent glass transition and homogeneous phase morphology, with no lower critical solution temperature (LCST) behavior upon heating to high temperature, indicating their miscibility. The Tg-composition relationship was proper described by the Kwei equation with moderate fitting parameters as k = 0.4 and q = 85. The observed heat of fusion (ΔHf) of P(BA-co-BT) revealed an obvious negative deviation from linearity with respect to the TA content, suggesting the presence of specific interactions between TA and P(BA-co-BT). Fourier-transform infrared spectroscopy (FTIR) was further conducted to identify the specific interactions. It demonstrated that the absorption of TA self-associated OH group gradually vanished and a low-frequency shift for TA phenolic-stretching band was occurred with increasing the P(BA-co-BT) content. Carbonyl-stretching bands were also resolved and were varied with the blending compositions. IR evidence reveals the existence of intermolecular hydrogen bonds in the blends, which is suggested as the main factor of the miscibility for TA/P(BA-co-BT) blends. The hydrogen bonds between TA and P(BA-co-BT) also significantly affected the behavior of nonisothermal crystallization in the blends. The nonisothermal crystallization of crystalline P(BA-co-BT) was found to be retarded by amorphous TA owing to their intimate mixing caused by noted interactions of hydrogen bonds.