鲁东大学《CES》：石墨烯 PPy复合水凝胶，用于柔性传感器

1成果简介

自愈合水凝胶在柔性可穿戴设备领域具有广泛的应用潜力。本文，鲁东大学魏凯、柏良久 教授等在《Chemical Engineering Science》期刊发表名为“Self-healing, tough hydrogels with long-lasting moisture and extreme temperature tolerance and application for flexible sensors”的论文，研究通过Ritter反应同时还原和功能化石墨烯氧化物（GOs），随后在还原石墨烯氧化物（rGOs）表面进行吡咯的氧化聚合，从而制备出功能性纳米复合材料（rGOs@PPy）。该rGOs@PPy展现出优异的电化学性能，确保了水凝胶的电导率，可用于柔性传感器的开发。

rGOs@PPy水凝胶具有卓越的力学性能（应变可达1000%）和显著的自愈合能力（约85%），这归因于可逆的非共价键相互作用。此外，这些水凝胶还具有多个显著优势，包括高灵敏度（响应时间约为191毫秒）和宽广的操作温度范围（-20至45°C）。值得注意的是，该复合水凝胶可用于构建可穿戴应变传感器，能够监测关节运动及微弱脉冲。这些传感器可生成对应于不同运动的信号，且在多次运动循环后信号仍保持近乎稳定。凭借卓越的灵敏度、高识别能力和相对稳定性，这些柔性传感器展现出广阔的应用前景。

2图文导读

方案1. (a) Fabrication of rGOs@PPy; (b) self-healing mechanism and anti-freezing of rGOs@PPy-hydrogels.

图1. TEM images of (a) GOs, (b) rGOs, and (c) rGOs@PPy; (d) FTIR spectra of GOs, rGOs, and rGOs@PPy; (e) Raman spectra of GOs, rGOs, and rGOs@PPy; (f) TGA curves of GOs, rGOs, and rGOs@PPy.

图2. (a) XPS wide-scan spectra of GOs, rGOs, and rGOs@PPy; XPS high resolution spectra of C 1s of (b) GOs, (c) rGOs, and (d) rGOs@PPy.

图3. (a) Stress–strain curves of rGOs@PPy-hydrogels with different amounts of Fe(III); (b) with different amounts of rGOs@PPy; (c) with different volume ratios of glycerin; stress–strain curves of rGOs@PPy-hydrogels (d) with or (e) without glycerol at different temperatures; (f) with different healing times.

图4. (a) The strain sweeps measurements of original rGOs@PPy-hydrogels; (b) modulus changes of recovered rGOs@PPy-hydrogels after the 1000 % strain deformation (t = 300 s, γ = 1 %); (c) dynamic strain amplitude cyclic test for rGOs@PPy-hydrogels (γ = 1 % or 400 %. Alternating time intervals was 13 s); (d) the FTIR spectra of rGOs@PPy-hydrogels (The above hydrogels were all prepared with rGOs@PPy = 10 mg; FeCl3·6H2O = 6.0 mg; GV% = 12.5 %).

图5. Self-healing process images of hydrogels under light microscopy, (a) t = 0 min; (b) t = 30 min; (c) t = 60 min; (d) t = 100 min (Tests are operated at room temperature). The conductivity of different hydrogels (e) before and (f) after healing at room temperature.

图6. (a) Relationship between relative resistance change (ΔR/R0) and strain for rGOs@PPy-hydrogels sensor; (b) the sensor responded to loading–unloading of 20 % strain; (c) selected a sensing interval from 300 cycles; (d) response and recovery time for strain of the sensor; (e) resistance response of the sensor; (f) relative resistance change at −20 °C (20 % strain).

图7. rGOs@PPy-hydrogels sensor for detection of human motions. Immediate response of the sensor to (a) elbow flexion; (b) knee flexion; a slight movement of the human body (c) pulse, and (d) heartbeat; (e) the bending of the index finger; (f) the bending of the index finger before and after healing.

3小结

综上所述，成功制备了具有自愈合、耐用和保湿性能的rGOs@PPy水凝胶，适用于极端温度下的柔性传感应用。通过在rGOs表面聚合吡咯，合成了rGOs@PPy，从而提高了水凝胶的机械强度和导电性。甘油被引入与水形成二元溶剂。甘油与水之间的氢键确保了水分子在高温下被保留，并在低温下避免结冰，为传感应用提供了必要条件。添加Fe(III)优化了水凝胶的自愈合能力（效率85%）。此外，成功制备了具有高灵敏度（响应时间191毫秒）和宽工作温度范围（-20–45°C）的水凝胶传感器。鉴于这些优异特性，基于有机水凝胶的应变传感器在软机器人、可穿戴电子设备、电子皮肤和健康监测等领域具有广阔的应用前景。

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来源：材料分析与应用