Tannic Acid Crosslinked Self‐Healing and Reprocessable Silicone Elastomers with Improved Antibacterial and Flame Retardant Properties

Abstract

Silicone elastomers are widely used in aviation, electronics, automotive, and medical device fields, and their overuse inevitably causes recycled problems. In addition, the elastomers are subject to attack by bacteria and fire during use in some application scenarios, which is a safety hazard. Therefore, there is a great need to prepare silicone elastomers with improved antibacterial, flame retardant, self-healing, and recyclable functions. A new strategy is proposed to prepare silicone elastomers with bio-based tannic acid as cross-linkers to solve this problem by using polydimethylsiloxane as a soft chain segment and 2,2-bis(hydroxymethyl)propionic acid as an intermediate chain extender. Based on the phenol carbamate bonding and hydrogen bonding interactions, the elastomer has efficient self-healing ability and can achieve dynamic dissociation at 120 °C for complete recovery. In addition, due to the unique spatial structure and polyphenolic hydroxyl groups of tannic acid, the mechanical properties of the elastomer are greatly improved with an antimicrobial efficiency of over 90% and a final oxygen index of 25.5%. The multifunctional silicone elastomer has great potential applications in recyclable refractory materials and antimicrobial materials.

A hybrid reversible crosslinked polysiloxane elastomer with high toughness and recyclability

“…Upon increasing the temperature from 30°C to 150°C, a significant enhancement in the transmission peaks of C=O groups engaged in hydrogen bonding within urea and urethane was observed. There was also a gradual increase in N‐H stretching vibrations associated with hydrogen bonds 31 . These observations suggested the occurrence of a dissociation mechanism for hydrogen bonds within the rigid domain as temperature increased.…”

“…PDMS 3 ‐IPDI 4 ‐SS‐F and its corresponding D‐A crosslinking product, PDMS 3 ‐IPDI 4 ‐SS‐F‐M, were further characterized using FTIR spectra, as depicted in Figure S2. The absence of the absorption peak at 2260 cm −1 suggested that the complete reaction had occurred for ‐NCO 31 . The appearance of a new peak at 1722 cm −1 indicated the presence of D‐A covalent bonds in the crosslinking product PDMS 3 ‐IPDI 4 ‐SS‐F‐M 27 .…”

“…There was also a gradual increase in N-H stretching vibrations associated with hydrogen bonds. 31 These observations suggested the occurrence of a dissociation mechanism for hydrogen bonds within the rigid domain as temperature increased. Therefore, these results demonstrated the successful formation of polysiloxane elastomers with the hybrid reversible crosslinked network.…”

“…The absence of the absorption peak at 2260 cm À1 suggested that the complete reaction had occurred for -NCO. 31 The appearance of a new peak at 1722 cm À1 indicated the presence of D-A covalent bonds in the crosslinking product PDMS 3 -IPDI 4 -SS-F-M. 27 The characteristic peak at 3408 cm À1 could be attributed to the tensile vibration of -NH. 17 Moreover, the PDMS 3 -IPDI 4 -SS-F-M elastomer was characterized using variable temperature infrared (VTIR) spectroscopy, enabling the observation of dynamic changes in urea H-bonds and urethane H-bonds (Figure 2).…”

Synergistic Self-Healing Enhancement in Multifunctional Silicone Elastomers and Their Application in Smart Materials

“…High-performance antimicrobial and antifouling materials with an in-built ability to recover mechanical strength can be used as fouling-release and corrosion-resistant polymer coatings. For example, flame retardant, self-healing and recyclable hybrid materials with >90% antimicrobial efficiency were obtained with PDMS, 2,2-bis(hydroxymethyl)propionic acid as the intermediate chain extender and crosslinked by interactions with tannic acid that is a natural antimicrobial substance [ 97 ]. The products exhibited good mechanical and tensile properties, with σ max up to 7.5 MPa and ε max up to 1540%.…”