Nanocomposite Hydrogels with Optic–Sonic Transparency and Hydroacoustic-Sensitive Conductivity for Potential Antiscouting Sonar

Abstract

In this paper, we report on the design and simple fabrication of novel nanocomposite hydrogels with optic−sonic transparency and hydroacoustic-sensitive conductivity. The proposed nanocomposite hydrogels are constructed by poly(N,Ndimethylacrylamide) and exfoliated Laponite clay nanosheets via free radical polymerization. With lithium chloride (LiCl) as ionic additives inside the polymeric networks of the hydrogels, the lithium cations (Li + ) could be stored on and in the clay nanosheets owing to the electrostatic adsorption and cation exchange. Triggered by hydroacoustic wave oscillation, the stored Li + ions could escape from the clay nanosheets, resulting in the augmentation of ionic concentration inside the polymeric networks and thus the increase of the conductivity of the nanocomposite hydrogel. Inversely, upon removing the hydroacoustic signals, the Li + ions could be readsorbed again by the clay nanosheets; as a result, the conductivity of the nanocomposite hydrogel decreases again. Moreover, the fabricated nanocomposite hydrogels also feature high stretchability and spliceable and antifreezing properties. Such novel nanocomposite hydrogels are highly promising for development of systems for camouflaging and sensing sonar scanning.

Multifunctional Role of MoS2 in Preparation of Composite Hydrogels: Radical Initiation and Cross-Linking

“…In particular, soft, nanocomposite hydrogels have benefited from the elastic, cross-linked networks that confine a considerable amount of water and additive nanomaterials that induce tailored, complex properties, and now hold privileged positions in the development of smart, elastic materials. − Typically, colloidal nanoparticles including nanowires or carbon dots have been widely used, − and more recently, two-dimensional layered materials such as ceramic nanosheets, carbides, graphene oxides, and covalent organic framework have been extensively researched. − They have relatively weak intermolecular interactions between the layers and thus show large surface areas and accessible active sites that are exposed on the surface, which imparts sophisticated yet essential properties to the polymeric networks. , Among many layered materials, molybdenum disulfide (MoS 2 ) has been incorporated in hydrogel networks due to its mechanical or electronic properties; recently, the embedded hydrogels have been used as a functional platform for energy-related or environmental applications such as separation or catalysis under aqueous conditions. − When designing the materials via a bottom-up approach, MoS 2 and other monomeric components are dispersed on a molecular level; thereafter, the composite networks are set, usually, by radical polymerization while leaving the inorganic material as an exogenous additive in most cases. Conversely, from the perspective of polymer chemistry, the chemical function of MoS 2 that can play a significant role as a reactive component in the formation of hydrogels through radical polymerization has been rarely investigated.…”

Triple crosslinking conductive hydrogels with digitally printable and outstanding mechanical stability for high-resolution conformable bioelectronics

“…8,89 Thus, it was hypothesized that when LAPONITE® and BIS were used as crosslinkers simultaneously, the hydrogels would form a DN structure, with LAPONITE® acting as the main crosslinker to obtain good tensile characteristics and BIS acting as a co-crosslinker to stabilize the network structure. 90 In this context, one experiment was established to evaluate the effect of BIS, LAPONITE®, and Ga as crosslinkers (Fig. 4a(v)).…”

Strategies for interface issues and challenges of neural electrodes

“…147,148 Recently, owing to the inherent remarkable biocompatibility, flexibility, biological activity, and compliance with nerve tissue, hydrogels have been widely used in the biological investigation including cell culture, 149–151 drug delivery, 152–155 tissue repair, 156–158 reconstruction, etc . 159–161 Simultaneously, hydrogels have also been employed in the manufacture of functional devices, such as sensors, 163–165 optics, 165–167 bioelectronics and so on. Importantly, as candidate materials for flexible bioelectronics, hydrogels have become a momentous part of neural electrodes.…”