Pinelli Filippo, Nespoli Tommaso, Rossi Filippo
Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, 20131 Milan, Italy.
Gels. 2021 Sep 24;7(4):149. doi: 10.3390/gels7040149.
Porous aerogels, formed by subjecting precursor hydrogels using a freeze-drying process, are certainly one of the most studied and synthetized soft materials, thanks to their important features such as elasticity, swelling behavior, softness, and micro and nanosized pores, which guarantee their applicability in various fields. Typically, these systems are synthetized working with natural or synthetic polymers, but in the last years great interest has been given to proper formulated aerogels able to combine polymeric structures with other moieties such as graphene or graphene oxide. This working strategy can be pivotal in many cases to tune important properties of the final system such as toughness, porosity, elasticity, electrical conductivity, or responsive behavior. In this work we propose the synthesis of chitosan graphene oxide aerogels obtained through self-assembly of graphene oxide sheets and chitosan chains. These three-dimensional systems were chemically characterized with IR and XRD technique and their inner structure was investigated through the scanning electron microscopy (SEM). Moreover, we mechanically characterized the material through dynamic mechanical analysis, showing the stability of these systems. Finally, the adsorption ability of these soft materials has been demonstrated using model molecules to simulate water contaminants showing the efficacy of those graphene-based systems even for the removal of anionic dyes. Complete removal of contaminants was obtained at low concentration of dyes in solution (100 mg/L), while with a higher amount of pollutant in the solution (350 mg/L) high sorption capacity (q > 200 mg/g) was observed.
通过冷冻干燥工艺对前体水凝胶进行处理而形成的多孔气凝胶，无疑是研究和合成最多的软材料之一，这得益于它们具有弹性、膨胀行为、柔软性以及微米和纳米尺寸的孔隙等重要特性，这些特性保证了它们在各个领域的适用性。通常，这些体系是通过使用天然或合成聚合物来合成的，但在过去几年中，人们对能够将聚合物结构与其他部分（如石墨烯或氧化石墨烯）相结合的适当配方气凝胶产生了极大的兴趣。在许多情况下，这种工作策略对于调节最终体系的重要性能（如韧性、孔隙率、弹性、电导率或响应行为）可能至关重要。在这项工作中，我们提出了通过氧化石墨烯片和壳聚糖链的自组装来合成壳聚糖氧化石墨烯气凝胶。这些三维体系通过红外光谱（IR）和X射线衍射（XRD）技术进行了化学表征，并通过扫描电子显微镜（SEM）研究了它们的内部结构。此外，我们通过动态力学分析对材料进行了力学表征，显示了这些体系的稳定性。最后，使用模型分子模拟水中污染物，证明了这些软材料的吸附能力，表明这些基于石墨烯的体系即使对于去除阴离子染料也具有有效性。在溶液中染料浓度较低（100 mg/L）时可实现污染物的完全去除，而在溶液中污染物含量较高（350 mg/L）时，则观察到了高吸附容量（q > 200 mg/g）。
