Macromolecular Radical Networks as a Novel Magnetic Material

The corrosion, toxicity, and sustainability concerns that beset traditional magnetic materials containing heavy metals and rare-earth elements may be abated through replacement with petroleum-derived organic radicals. Previous work has investigated doping polymer gel networks with an organic radical solution to induce a paramagnetic response in lieu of metals. However, this system proved vulnerable to rapid solution leeching and a corresponding loss of magnetic properties. To facilitate a prolonged retention of organic radicals, we have alternatively developed intrinsically magnetic polymer gels that can yield nitroxide radicals upon oxidation. This project specifically looks at networks of TMPM monomers (a TEMPO methacrylate precursor) connected by common difunctional crosslinkers such as EGDMA, bisacrylamide, bisphenol A, and PEGDA.

Our focus on polymer networks allows us to introduce favorable functionalities such as on-demand demagnetization, as well as control over network structure, swelling properties, and mechanical behavior. By coupling the rheological, magnetic, and chemical behavior of candidate crosslinkers and copolymers, we aim to establish design rules for a biocompatible organic magnetic material that can enhance magnetically-actuated devices such as microrobots for medical applications.