Alkyl Chain Length Effects of Imidazolium Ionic Liquids on Electrical and Mechanical Performances of Polyacrylamide/Alginate-Based Hydrogels

Abstract

Conductive hydrogels with stretchable, flexible and wearable properties have made significant contributions in the area of modern electronics. The polyacrylamide/alginate hydrogels are one of the potential emerging materials for application in a diverse range of fields because of their high stretch and toughness. However, most researchers focus on the investigation of their mechanical and swelling behaviors, and the adhesion and effects of the ionic liquids on the conductivities of polyacrylamide/alginate hydrogels are much less explored. Herein, methacrylated lysine and different alkyl chain substituted imidazole-based monomers (IMCx, x = 2, 4, 6 and 8) were introduced to prepare a series of novel pAMAL-IMCx-Ca hydrogels. We systematically investigated their macroscopic and microscopic properties through tensile tests, electrochemical impedance spectra and scanning electron microscopy, as well as Fourier transform infrared spectroscopy, and demonstrated that an alkyl chain length of the IMCx plays an important role in the designing of hydrogel strain sensors. The experiment result shows that the hexyl chains of IMC6 can effectively entangle with LysMA through hydrophobic and electrostatic interactions, which significantly enhance the mechanical strength of the hydrogels. Furthermore, the different strain rates and the durability of the pAMAL-IMC6-Ca hydrogel were investigated and the relative resistance responses remain almost the same in both conditions, making it a potential candidate for wearable strain sensors.

Mechanically robust and highly bactericidal macroporous polymeric gels based on quaternized N,N-(dimethylamino)ethyl methacrylate possessing varying alkyl chain lengths

“…This can be attributed to the presence of relatively more secondary hydrophobic interactions in the gels fabricated using the quaternized C8 monomers as compared to the C6 and C8 gels which are more brittle in nature and break at lower strain. 39–41…”

“…This can be attributed to the presence of relatively more secondary hydrophobic interactions in the gels fabricated using the quaternized C8 monomers as compared to the C6 and C8 gels which are more brittle in nature and break at lower strain. [39][40][41] Further, tensile testing has been done for the gel samples designated as C8-2.5, C8-5, C8-10, and C8-15, and the results are presented in Fig. 7(c and d), Fig.…”

Electroactive and Stretchable Hydrogels of 3,4-Ethylenedioxythiophene/thiophene Copolymers

“…FT-IR (Thermo Fisher Scientific Nicolet iS5) was used to characterize the molecular features and intermolecular forces of the copolymers and hydrogels, respectively. The morphologies of hydrogels were carried out using the SEM (JSM-7600F), and the hydrogel samples were prepared according to our previous report . The rheological measurements of the hydrogels were achieved by a TA rheometer (DHR-1) with a parallel plate setup (diameter of 20 mm and a gap of 1 mm).…”

“…The morphologies of hydrogels were carried out using the SEM (JSM-7600F), and the hydrogel samples were prepared according to our previous report. 8 The rheological measurements of the hydrogels were achieved by a TA rheometer (DHR-1) with a parallel plate setup (diameter of 20 mm and a gap of 1 mm). The mechanical experiments were recorded on a tensile tester (Gotech AI-3000-U).…”

“…Conductive hydrogels are important materials for the fabrication of flexible and wearable electric sensors because of their outstanding designability, good biocompatibility, high stretchability, excellent electrical conductivity, strong adhesion, and so on. − These well-designed conductive hydrogels have been extensively used in the field of electronic skins, − wearable devices, − flexible sensors, − human motion monitoring, , and brain–computer interface …”