Tough and Self-Healable Nanocomposite Hydrogels for Repeatable Water Treatment

Abstract

Nanomaterials with ultrahigh specific surface areas are promising adsorbents for water-pollutants such as dyes and heavy metal ions. However, an ongoing challenge is that the dispersed nanomaterials can easily flow into the water stream and induce secondary pollution. To address this challenge, we employed nanomaterials to bridge hydrogel networks to form a nanocomposite hydrogel as an alternative water-pollutant adsorbent. While most of the existing hydrogels that are used to treat wastewater are weak and non-healable, we present a tough TiO2 nanocomposite hydrogel that can be activated by ultraviolet (UV) light to demonstrate highly efficient self-healing, heavy metal adsorption, and repeatable dye degradation. The high toughness of the nanocomposite hydrogel is induced by the sequential detachment of polymer chains from the nanoparticle crosslinkers to dissipate the stored strain energy within the polymer network. The self-healing behavior is enabled by the UV-assisted rebinding of the reversible bonds between the polymer chains and nanoparticle surfaces. Also, the UV-induced free radicals on the TiO2 nanoparticle can facilitate the binding of heavy metal ions and repeated degradation of dye molecules. We expect this self-healable, photo-responsive, tough hydrogel to open various avenues for resilient and reusable wastewater treatment materials.

Polymer Conformations, Entanglements and Dynamics in Ionic Nanocomposites: A Molecular Dynamics Study

“…One way to provide NP dispersion is to let the interaction between NPs and chains to be of an ionic nature [18][19][20]. The presence of oppositely charged ions at the polymer/nanofiller interphase can promote dispersion [21][22][23][24][25]. This relatively new class of ionic nanocomposites combines filler reinforcement with the reversibility of ionic interactions [23].…”

“…This relatively new class of ionic nanocomposites combines filler reinforcement with the reversibility of ionic interactions [23]. Despite the improved mechanical performance, the reversible feature of ionic bonds, that can break and reform under certain conditions [21], has led to smart materials for self-healing [25,26], shape-memory [21,22], piezoelectric [27], and mechanochromic [28] applications due to their ability to respond directly under a certain chemical or physical stimulus. For instance, nanocomposites based on imidazolium-functionalized polyurethane and surface-modified sulfonate silica (SiO 2 ) NPs have revealed not only unprecedented mechanical properties with simultaneous improvements in stiffness, toughness and extensibility but also a scratch recovery ability [21].…”

Synthesis, Characterization, and Antifogging Application of Polymer/Al2O3 Nanocomposite Hydrogels with High Strength and Self-Healing Capacity

“…In previous reports, NC gels were investigated for various applications, such as tissue engineering [47], water treatment [36], strain sensors [48], and 3D printing [49] due to their unique physiochemical properties. Herein, based on the water-absorbing ability and the highly transparent appearances of PAS gels at both dry and swollen states, we attempted to explore the applications of PAS gels as potential antifogging materials.…”

“…As a result, these noncovalent interactions could also endow NC gels with a self-healing ability in addition to excellent mechanical properties. This hypothesis has already been successfully verified by several groups, and a series of high-strength and self-healing NC gels have been achieved using different nanomaterials, including clay nanosheets [34], graphene oxide (GO) [35], TiO 2 [36], and Zr(OH) 4 nanoparticles [37]. In our previous reports, we developed a new type of NC gels using alumina nanoparticles (Al 2 O 3 NPs) as cross-linkers [38,39].…”

Functionalization of Molecularly Imprinted Polymer Microspheres for the Highly Selective Removal of Contaminants from Aqueous Solutions and the Analysis of Food-Grade Fish Samples

“…Increasing worldwide concern regarding environmental pollution has inspired researchers to explore high-performance functional materials to remediate the contaminated global environment, especially aquatic systems that have a key impact on human life and food supply [1,2,3,4,5,6,7,8,9,10,11,12]. Various kinds of functional materials have thus been reported for achieving environmental remediation [3,4,13,14,15,16,17,18,19,20,21].…”