Anisotropically Functionalized Nanotube Anchors For Improving The Mechanical Strength Of Immiscible Polymer Composites

Plastic recycling is limited due to the immiscibility of most polymers and the weakness of the corresponding interface. Here, a method to synthesize block nanotubes in a scalable manner is described, and one example is shown where these nanotubes strengthen polymer-polymer interfaces. The method relies on the incorporation of nitrogen atoms selectively within the nanotube structure during growth. By rapidly changing the reaction environment, blocks of nitrogen functionality along the length of the nanotube result. The change in the local electronic environment and radical scavenging property of the nanotube near the nitrogen atoms was used to selectively polymerize styrene from the nanotube wall where nitrogen is incorporated. These diblock- functionalized nanotubes were placed at a poly(methyl methacrylate)/polystyrene (PMMA/PS) interface, and the fracture toughness was measured by the asymmetrical double cantilever beam test. The fracture toughness of the interface was found to increase by over 1000% compared to that of the bare interface and 400% over the interface with nonfunctionalized nanotubes.