Electrospun Polymer Nanofibers Reinforced by Tannic Acid/Fe+++ Complexes

• Main Authors: Weiqiao Yang, Ana M. M. Sousa, Audrey Thomas-Gahring, Xuetong Fan, Tony Jin, Xihong Li, Peggy M. Tomasula, LinShu Liu
• Format: Article
• Language: English
• Published: MDPI AG 2016-09-01
• Series: Materials
• Subjects: complexation; polyphenol; antioxidant; mechanical reinforcement; electrospinning
• Online Access: http://www.mdpi.com/1996-1944/9/9/757

We report the successful preparation of reinforced electrospun nanofibers and fibrous mats of polyvinyl alcohol (PVA) via a simple and inexpensive method using stable tannic acid (TA) and ferric ion (Fe+++) assemblies formed by solution mixing and pH adjustment. Changes in solution pH change the number of TA galloyl groups attached to the Fe+++ from one (pH < 2) to two (3 < pH < 6) to three (pH < 7.4) and affect the interactions between PVA and TA. At pH ~ 5.5, the morphology and fiber diameter size (FDS) examined by SEM are determinant for the mechanical properties of the fibrous mats and depend on the PVA content. At an optimal 8 wt % concentration, PVA becomes fully entangled and forms uniform nanofibers with smaller FDS (p < 0.05) and improved mechanical properties when compared to mats of PVA alone and of PVA with TA (p < 0.05). Changes in solution pH lead to beads formation, more irregular FDS and poorer mechanical properties (p < 0.05). The Fe+++ inclusion does not alter the oxidation activity of TA (p > 0.05) suggesting the potential of TA-Fe+++ assemblies to reinforce polymer nanofibers with high functionality for use in diverse applications including food, biomedical and pharmaceutical.