轻质和超弹性芳纶纳米纤维/石墨烯复合气凝胶，用快速吸附粘性油

摘要：基于分离型芳纶纳米纤维（DANF）制备高性能气凝胶是回收废弃芳纶纤维的重要途径之一。然而，高能耗的干燥技术和性能不足的问题阻碍了其大规模生产和实际应用。本文，青岛科技大学杨洪生/张建明等研究人员在《Chemical Engineering Journal》期刊

1成果简介

基于分离型芳纶纳米纤维（DANF）制备高性能气凝胶是回收废弃芳纶纤维的重要途径之一。然而，高能耗的干燥技术和性能不足的问题阻碍了其大规模生产和实际应用。本文，青岛科技大学杨洪生/张建明等研究人员在《Chemical Engineering Journal》期刊发表名为“Ambient pressure dried, light-weight and superelastic aramid nanofibers/graphene composite aerogels for fast adsorption of viscous oils”的论文，研究开发了一种基于常压干燥（APD）方法的简单组装和改性工艺，该工艺能耗低，可利用DANF和还原石墨烯氧化物（RGO）制备高性能气凝胶。

通过APD制备的DANF气凝胶与聚合芳纶纳米纤维（PANF）组装的气凝胶相比，密度更低（低至28 mg/cm³，降低52%）且弹性更好。这可归因于DANF形成的更大且更坚固的孔壁。DANF气凝胶在极低温度（-196℃）和宽频率范围内均展现出稳定的弹性。此外，其热导率低（0.03 W/（m·K））且高温绝热率高（约70%,10 mm,300℃）。改性DANF/RGO气凝胶具有高疏水性（138°）及优异的太阳能-热能和电能-热能转换性能，可比DANF气凝胶更快地吸收高粘度油。更重要的是，由于其卓越的弹性和热稳定性，它们可通过挤出或蒸馏方式轻松回收。本研究提出了一种低能耗方法，实现废弃芳纶纤维的高价值再利用。

2图文导读

图1.用废芳纶纳米纤维制备DANF气凝胶和ANF/RGO气凝胶的过程。

图2.不同冷冻温度（a-c）、不同干燥温度（d-f）和不同固体含量（g-i）制备的 PANF 气凝胶和 DANF 气凝胶的照片、密度变化和收缩百分比变化。

图3.（A-F）PANF 气凝胶（a-c）和 DANF 气凝胶（d-f）分别放大的 SEM 图像。（g， h）分别是 PANF 和 DANF 的 TEM 图像。（i） PANF 和 DANF 薄膜的拉伸强度曲线与拉伸应变的关系。（j） PANF 和 DANF 薄膜在拉伸强度、模量和韧性方面的比较。（K） PANF 和 DANF 薄膜的 XRD 光谱。

图4. (a) Photographs of compressive tests of the PANF aerogel and DANF aerogel. (b, c) Cyclic compressive strength-strain curves of the PANF aerogel and DANF aerogel, respectively. (d) Photographs of compressive tests of the DANF aerogel from lateral direction and in the liquid nitrogen (−196 ℃), respectively. (e) The storage modulus, loss modulus, and damping ration variations of the DANF aerogel as a function of frequency at 3% strain. (f) The surface temperature variation curves of DANF aerogel on a heating platform with different temperatures as a function of time. (g) Thermal infrared images of the DANF aerogel on a heating platform (300 ℃) for different time. (h) The temperature barrier ratios of DANF aerogel on a heating platform with different temperatures. (i) Comparison of DANF aerogel with other kinds of typical aerogels in thermal conductivity.

图5. (a) Preparation process of DANF/GO aerogels. (b, c) The photographs (b) and density (c) of the ANF/GO aerogels with different infusing number of GO dispersion. (d) Macroscopic comparison of hydrophobicity between ANF aerogel and DANF/RGO aerogel. (e) SEM images of the cross section of the DANF/RGO aerogel. (f) The water contact angles of DANF/RGO aerogels with different infusing number of GO dispersion. (g) The adsorption ratios of DANF/RGO aerogels for different types of oils. (h) Compressive strength-strain curves of DANF/RGO aerogels with different infusing number of GO dispersion.

图6. (a) Thermal infrared images of ANF aerogel and DANF/RGO aerogel under different light intensity. (b) Comparison of viscous oil adsorption speed between ANF aerogel and DANF/RGO aerogel under the same light intensity. (c) Thermal infrared images of the DANF/RGO aerogel with different incoming current. (d) Comparison of viscous oil adsorption speed between ANF aerogel and DANF/RGO aerogel with a current of 0.2 A.

图7. (a) Photographs of cyclic utilization of the DANF/RGO aerogel for oil adsorption by compressing. (b) Photographs of cyclic utilization of the DANF/RGO aerogel for oil adsorption by distillation. (c) Adsorption capacity retention of DANF/RGO aerogel as a function of compressing number with a compressive strain of 50%. (d) Adsorption capacity retention of DANF/RGO aerogel as a function of distillation number.

3小结

综上所述，我们开发了一种低能耗的APD方法，利用废弃芳纶纤维制备出更轻便且弹性更好的气凝胶。与PANF相比，DANF由于具有更好的界面相互作用和机械强度，在冰模板的作用下形成了更大的孔隙和更坚固的孔壁，这有利于抵抗气液界面张力。因此，在相同工艺条件下，APD制备的DANF气凝胶的密度（28 ∼ 59 mg/cm³）低于PANF气凝胶（43 ∼ 80 mg/cm³）。此外，DANF气凝胶和PANF气凝胶在50%压缩应变下经50次循环压缩后，塑性变形率分别为约11%和15%。因此，DANF气凝胶的压缩弹性优于PANF气凝胶。此外，DANF气凝胶在超低温（-196℃）和不同频率下均表现出稳定的弹性。其热导率低（0.03 W/（m·K）），因此在300℃高温下,1 cm厚样品的保温率高达70%。功能性DANF/RGO气凝胶通过简单的浸渍、APD和退火工艺制备。改性气凝胶呈现疏水性，水接触角可达137°。其展现出优异的太阳能热转换和电热转换性能，且在日光照射或通电状态下可快速吸收粘稠液体，而DANF气凝胶不具备此特性。更重要的是，由于其坚固的涂层微结构、卓越的弹性和高温热稳定性，功能性气凝胶可通过简单挤出或蒸馏实现重复利用。本研究开发了一种低能耗方法，实现了废弃芳纶纤维的高价值再利用。

文献：