Role of Nanoparticle-Polymer Interactions on the Development of Double-Network Hydrogel Nanocomposites with High Mechanical Strength

Abstract

Extensive experimental and theoretical research over the past several decades has culminated in the understanding of the mechanisms behind nanoparticle-mediated enhancements on the mechanical properties of hydrogels. This information is not only crucial to realizing applications that directly benefit from developing hydrogels with high mechanical strength, but also to guide the development of strategies to further enhance hydrogel properties by combining different approaches. In our study, we investigated the effect of combining two approaches – addition of nanoparticles and crosslinking two different polymers (to create double-network hydrogels) – on the mechanical properties of hydrogels. Our studies revealed that these approaches may be combined to synthesize hydrogel composites with enhanced properties; however, both polymers in the double-network hydrogel must strongly interact with the nanoparticles to fully benefit from the addition of nanoparticles. Moreover, the concentration of hydrogel monomers used for the preparation of the double-network hydrogels had a significant effect on the extent of nanoparticle-mediated enhancements; double-network hydrogel nanocomposites prepared using lower monomer concentrations showed higher enhancements in elastic moduli compared to those prepared using high monomer concentrations. Collectively, these results demonstrate that the hypotheses previously developed to understand the role of nanoparticles on the mechanical properties of hydrogel nanocomposites may be extended to double-network hydrogel systems and guide the development of next generation hydrogels with extraordinary mechanical properties through a combination of orthogonal approaches.

Multifunctional Hydrogel Nanocomposites for Biomedical Applications

“…However, their poor mechanical strength limits their uses to solely non-load bearing applications [4][5][6][7][8][9]. Therefore, researchers have investigated improving the mechanical properties of hydrogels via multiple approaches including, but not limited to, the incorporation of nanoparticles or the addition of a second polymer network to form interpenetrating-or double-network (IPN or DN) hydrogels [2,[10][11][12][13][14][15][16]. Nanoparticles are thought to improve the mechanical properties of hydrogels by forming links with the polymer chain that can desorb under stress, relieving some of the tension within the hydrogel network [10,17,18].…”

“…Nanoparticles have also been used to improve the properties of IPN and DN hydrogels for a wide variety of applications (e.g. tissue engineering, antimicrobial hydrogels, and wearable devices) [5,14,22,31,38,39]. Researchers have investigated using clay, oxide, and quantum dot nanoparticles to improve the properties of IPN and DN hydrogels [5,20,22,31,38,39].…”

Reinforced Polymer Composites

“…The remaining three papers in this Special Issue do not relate to polymer composites reinforced with fiber fillers. Chang et al [ 19 ] investigate the effect of combining two approaches, namely the addition of nanoparticles and the crosslinking of two different polymers to create double-network hydrogels, on the mechanical properties of hydrogels. It is evaluated that the introduction of nanomaterials into the hydrogel network may allow the consideration of double-network hydrogels for new applications such as self-healing, shape memory, 3D printing, and dye removal.…”