碳纳米管／聚丙烯酰胺复合水凝胶的制备及性能

Preparation of G-CNTs/PAAm hydrogel and its properties

通过活度2.072×1015 Bq、剂量率2 k Gy·h-1的钴-60进行辐照接枝和辐照交联两步法制备了碳纳米管复合水凝胶。使用傅里叶红外光谱(Fourier Transform Infrared spectroscopy,FTIR)、热释重分析(Thermal gravimetric analysis,TGA)、透射电子显微镜(Transmission electron microscope,TEM)、X射线衍射(X-ray diffraction,XRD)、BET比表面积(Brunauer-Emmett-Teller Specific Surface Area)等方法对样品进行了表征。结果显示,改性后的碳纳米管(Carbon nanotubes,G-CNTs)的管壁出现了明显的链段,其傅里叶红外光谱在1 452 cm-1和1 726 cm-1处多了两个吸收峰;碳纳米管复合水凝胶的BET值(30 m2·g-1)比聚丙烯酰胺水凝胶的(12 m2·g-1)提高了一倍多。实验结果表明丙烯酸被成功接枝到CNTs的管壁上。G-CNTs在凝胶中均匀分散,并提高了复合水凝胶的比表面积和机械强度。

Background： Hydrogel has been widely applied to drug delivery, tissue engineering, water treatment, water retention and separation, etc. Mechanical properties of hydrogel can be improved by combining with other materials without changing its intrinsic properties. Due to the excellent properties of carbon nanotubes （CNTs） such as mechanical strength, hydrogen storage, high specific surface area, they can be applied to selective absorption or separation of hydrogen isotope. CNTs composite hydrogel may combine these excellent properties. Purpose： This study aims at a new absorbent material fabricated by irradiation-induced grafting and crosslinking two-steps method. Methods： The G-CNTs/PAAm hydrogel with Poly（acrylamide） and CNTs grafted with acrylic acid were fabricated by irradiation-induced grafting and crosslinking two-steps method. Properties of G-CNTs and CNTs were investigated by Fourier transform infrared spectroscopy （FTIR）, thermal gravimetric analysis （TGA）, and transmission electron microscope （TEM）. X-ray diffraction （XRD） and Brunauer-Emmett-Teller specific surface area （BET） were used to characterize PAAm hydrogel and G-CNTs/PAAm hydrogel. Liquid water and vaporous water absorption ability of G-CNTs/PAAm hydrogel and PAAm hydrogel were tested at room temperature. Results： Many objects and pieces appeared on the surface of G-CNTs. There were two new absorption bands at 1 726 cm-1 and 1 452 cm-l in the FTIR spectra of the G-CNTs which indicates that acrylic acid has been successfully introduced onto the surface of CNTs by Co-60 irradiation grafting. According to TGA curves of CNTs and G-CNTs, grafting ratio of G-CNTs （15%） could be calculated. The gel content of G-CNTs/PAAm hydrogel and PAAm hydrogel were 95.6% and 94.7%, respectively. Compared with PAAm hydrogel, two new peaks at 26.5° and 43.2° could be found in the XRD pattern of G-CNTs/PAAm hydrogel associated with CNTs and G-CNTs. The surface area of G-CNTs/PAAm hydrogel with 30 m2·g-1 was two times larger than that of PAAm hydrogel with 12 m2.g-1. Conclusion： Due to the larger surface area of G-CNTs/PAAm hydroge, better vaporous water absorption ability was shown compared with the PAAm hydrogel. Hydrophilic and dispersibility of CNTs in water have been improved and the crystal lattices of CNTs still exist after being grafted. The existence of G-CNTs improves the surface area and stables the structure of G-CNTs/PAAm hydrogel.