Magnetically Induced Self–Healing in Iron Oxide–Poly(ethylene oxide) Nanocomposites*

Current research aims to quantify self-healing capabilities of iron oxide (Fe₃O₄) nanoparticle (NP) infused poly(ethylene oxide) (PEO). Iron oxide NPs of varying surface chemistries (bare, aminopropyl triethoxysilane coated, and polyethylene glycol α–, ω–diphosphate coated) are used to prepare nanocomposites of varying concentrations less than 1% by weight. Each sample, in the form of a cylindrical disc, is indented using a LECO M400 Microindenter at five different locations between the center and edge. The indentation site is examined before and after being placed in an alternate magnetic field (AMF) to induce healing. The micrographs of each indent were collected with an Olympus PMEG microscope at the same imaging parameters. Healing efficiency is quantified using visual and software-based image analysis, identifying the percentage of healing as a function nanoparticle concentration and surface chemistry. Multiple methods of software-based image analysis were developed to perform this analysis. Nanoindentation experiments were also carried out to evaluate impact of surface coating and concentration on mechanical properties and viscoelastic behavior of these nanocomposites.