Polydopamine As an Efficient and Robust Platform to Functionalize Carbon Fiber for High-Performance Polymer Composites

Carbon fibers (CFs), which exhibit excellent physical performances and low density, suffer from their low surface activity in some application. Herein, based on dopamine chemistry, we proposed an efficient method to functionalize them: through a simple dip-coating procedure, the CFs were inverted from amphiphobic to hydrophilic with deposition of polydopamine film. Furthermore, using polydopamine as a bridge, the hydrophilic functionalized CFs were transformed to be oleophilic after following octadecylamine grafting. To illustrate applications of this functionalization strategy, we added 15 wt % functionalized CFs into polar epoxy and nonpolar poly­(ethylene-co-octene), and as a consequence, their tensile strength respectively increase by 70 and 60%, which show greater reinforcing effect than the unmodified ones (35 and 35%). The results of dynamic mechanical analysis and scanning electron microscope observations indicate that this polydopamine-based functionalization route brought about satisfactory improvements in interfacial adhesion between fillers and matrix. Considering that this simple approach is facile and robust enough to allow further specific functionalization to adjust surface properties, these findings may lead to the development of new efficient strategies for surface functionalization of CFs that are of great interest to the industrial field

Graphene-Oxide-Sheet-Induced Gelation of Cellulose and Promoted Mechanical Properties of Composite Aerogels

By taking advantage of cellulose, graphene oxide sheets (GOSs), and the process of freeze-drying, we propose a simple and effective method to prepare green cellulose aerogels with significant mechanical improvements. The addition of GOSs could accelerate the gelation of cellulose solution, which was confirmed by differential scanning calorimetry and rheology. Detailed investigations including dynamic light scattering and ultraviolet spectroscopy revealed the existence of interaction between GOSs and cellulose chains, which might be responsible for the promotion of the gelation process. With the incorporation of only 0.1 wt % GOSs, the compression strength and Young’s modulus of the composite aerogels were dramatically improved by about 30 and 90% compared to with those of pristine cellulose aerogels, respectively. This method is believed to provide possibilities to combine the extraordinary performances of GOSs with the multifunctional properties of environmentally friendly cellulose-based aerogels, thus holding great potential for biological applications in the future