A Polyvinyl Alcohol–Tannic Acid Gel with Exceptional Mechanical Properties and Ultraviolet Resistance

Abstract

Design and preparation of gels with excellent mechanical properties has garnered wide interest at present. In this paper, preparation of polyvinyl alcohol (PVA)–tannic acid (TA) gels with exceptional properties is documented. The crystallization zone and hydrogen bonding acted as physical crosslinkages fabricated by a combination of freeze–thaw treatment and a tannic acid compound. The effect of tannic acid on mechanical properties of prepared PVA–TA gels was investigated and analyzed. When the mass fraction of PVA was 20.0 wt% and soaking time was 12 h in tannic acid aqueous solution, tensile strength and the elongation at break of PVA–TA gel reached 5.97 MPa and 1450%, respectively. This PVA–TA gel was far superior to a pure 20.0 wt% PVA hydrogel treated only with the freeze–thaw process, as well as most previously reported PVA–TA gels. The toughness of a PVA–TA gel is about 14 times that of a pure PVA gel. In addition, transparent PVA–TA gels can effectively prevent ultraviolet-light-induced degradation. This study provides a novel strategy and reference for design and preparation of high-performance gels that are promising for practical application.

Synergistic Antibacterial Effects of Gallate Containing Compounds with Silver Nanoparticles in Gallate Crossed Linked PVA Hydrogel Films

“…In this study, the gallate containing compounds, EGCG, Tannic acid, and Quercetin has been shown to allow for extensive crosslinking of PVA (88% hydrolyzed) as witnessed by concentration-dependent inhibition of dissolution with certain concentrations providing well-swollen (hydrogel) films (Figures 1 and 2 and Table 2). The crosslinking is likely due to extensive hydrogen bonding between the gallate hydroxyl groups of tannic acid and the PVA hydroxyl groups on PVA and has been noted by many previous studies using 99% hydrolyzed PVA [16][17][18]. These previous studies sought to further strengthen PVA matrices rather than impacting dissolution in water.…”

“…Gallate-containing molecules such as Tannic acid, Quercetin, and epigallocatechin gallate (EGCG) are polyphenols found in many plants and are known to have mild antibiotic effects against both gram-positive and -negative bacteria with minimal inhibitory concentrations determined in this laboratory of the order of 100 µg/mL as compared to silver nanoparticles at 2.5 µg/mL. The gallate-containing molecule Tannic acid, used for centuries to stabilize collagen in hides to produce leather, has been shown to create extensive hydrogen bonds with 99% hydrolyzed PVA to strengthen the polymer [16][17][18]. Similarly, unpurified tea polyphenol extracts which contain gallates have also been used with PVA in both a strengthening and antibacterial role [19][20][21].…”

Reducing fire hazards and enhancing the thermal stability, acoustical, and UV protection of polyvinyl alcohol using bio-based flame retardant

“…Shaohua et al reported that tannic acid and tannic acid derivatives can enhance the UV-protection of cotton fabrics. 56,57…”

“…Tannic acid increase UV blocking because of phenolic quinone reversible tautomerism and a π electron conjugation effect. Shaohua et al reported that tannic acid and tannic acid derivatives can enhance the UV-protection of cotton fabrics 56,57.…”