This study aimed to develop composite hydrogels with exceptional piezoelectric properties and pressure sensitivity. To achieve the objective, this study created a deep eutectic solvent (DES) by mixing choline chloride (ChCl), acrylamide (AM), and acrylic acid (AA). Barium titanate nanoparticles (BTNPs) were incorporated as fillers into the deep eutectic solvents (DES) to synthesize the composite hydrogels using frontal polymerization (FP). The mechanical and piezoelectric properties of the resulting composite hydrogels were analyzed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). This study found that the BTNPs/P(AM-co-AA) composite hydrogels exhibited excellent mechanical and piezoelectric properties. This is attributed to the high dielectric constant of BTNPs and the electrode polarization phenomenon when subjected to pressure. With a BTNPs content of 0.6 wt%, the maximum compressive strength increased by 3.68 times compared with the hydrogel without added BTNPs. Moreover, increasing the BTNPs content to 0.6 wt% resulted in a 1.48 times increase in generated voltage under the same pressure, compared with the hydrogel with only 0.2 wt% BTNPs. This study provides a method for preparing composite hydrogels with outstanding piezoelectric properties and pressure sensitivity.

This study employed urea (U), acrylamide (AM), and choline chloride (ChCl) as raw materials to synthesize a deep eutectic solvent (DES), incorporated dispersed Fe₃O₄ as a filler within the DES, and effectively fabricated Fe₃O₄/P(U-AM-ChCl) composite hydrogels through in situ polymerization (SP). The hydrogels were analyzed through Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The influence of different Fe₃O₄ contents on the swelling behavior, anti-fatigue properties, and adsorption efficiency of the composite hydrogels was thoroughly examined. The results indicated that, in comparison to the hydrogel lacking Fe₃O₄, the hydrogel containing 1 wt% Fe₃O₄ demonstrated enhanced swelling and anti-fatigue characteristics, with its equilibrium swelling ratio (ESR) increasing by 16.34%, the time to achieve swelling equilibrium decreasing by 60%, the maximum stress recovery rate rising by 7.8%, and the toughness recovery rate improving by 7.28%.The adsorption efficiency of the hydrogel was improved, and adsorption equilibrium was achieved more quickly, due to the supplementary adsorption sites introduced by Fe₃O₄. When the Fe₃O₄/P(U-AM-ChCl) composite hydrogel was immersed in a 120 mg/L Cu²⁺ so-lution for 48 h, the adsorption capacity reached 171.5 mg/g. This study introduces a novel, viable approach for synthesizing hydrogels with reduced pore sizes and enhanced functionality, while also illustrating their prospective utility in water purification applications.

Correction for ‘Investigation of pressure response, adsorption performance, and detection capability of multifunctional P(AM-Gly-ChCl)/N-CQDs composite hydrogels’ by Yuzuo Liu et al. , New J. Chem. , 2026, https://doi.org/10.1039/d6nj00101g.

In this work, high-performance P(AM-Gly-ChCl)/N-CQDs composite hydrogels were successfully prepared via in situ photopolymerization, achieving effective integration of a deep eutectic solvent system with nitrogen-doped carbon quantum dots.