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

Exploring the Application of Sustainable Poly(propylene carbonate) Copolymer in Toughening Epoxy Thermosets

Herein, poly­(propylene carbonate) (PPC) was used as initiator for ε-caprolactone polymerization to produce the poly­(ε-caprolactone)-<i>block</i>-poly­(propylene carbonate)-<i>block</i>-poly­(ε-caprolactone) (PCL-PPC-PCL) triblock copolymer, enabling innovative application of PPC as a toughening agent of epoxy thermosets. The interfacial interaction between PPC modifiers and epoxy was enhanced significantly because PCL blocks were miscible with epoxy matrix. The size of separated PPC modifiers decreased dramatically as the amphiphilic block copolymer formed nanophases in epoxy host. Consequently, with the incorporation of 30 wt % PCL-PPC-PCL modifier into the thermoset, the tensile elongation and the area under the stress–strain curves increased by more than 320% and 180%, respectively, compared with neat epoxy, indicating that an excellent toughening effect was achieved using this strategy. Considering that PPC possessed an ocean of attractive properties but suffered from its low glass transition temperature in implementation as mass products, this work may open up opportunities to extend the applications of PPC