Synthesis, Properties, And Applications Of Nanoparticle Ionic Materials

Nanoparticle Ionic Materials are a novel materials platform consisting of a nanoparticle core and a organic, typically polymeric canopy bonded by an ionic bond. These systems are a subset of a growing field of single-component nanohybrids, where the organic and inorganic components of a nanocomposite material are bonded to form a single independent unit. This approach is necessary to overcome the ubiquitous mixing problem inherent in creating inorganic/organic hybrid materials at length scales greater than small molecules. In order to create the ionic bond, a typical strategy involves the functionalization of the core particle with an oligomer carrying an easily ionizable group, before reacting that with the canopy containing a complementary ionizable group. Part of the work presented here demonstrates an alternate synthesis for silica, extendable to other metal oxides, utilizing the inherent surface charge of the nanoparticle to create ionic materials without using complex chemistry. A major attraction of the nanoparticle ionic materials is their tunable mechanical properties. Several authors have reported properties ranging from soft glassy materials to Newtonian fluids, depending on composition. An exhaustive study of the dependence of mechanical and thermal properties as a function of composition has been undertaken, and phase map has been created to inform future synthesis by design endeavors in this field. Addtionally, the effect of using multifunctional polymers that can link nanoparticles together has been studied, and it has been shown that the resulting materials are stiffer with the addition of even a small fraction of crosslinking polymers. The ionic bond is shown to have a large effect on these properties by increasing the modulus dramatically. Additionally, these materials are shown to form self-healing elastomers, with the ability to be molded repeatedly, and then to recover their elastic strength in the new conformation, opening avenues to novel materials for applications such as coatings