Nanofluid acrylate composite resins—initial preparation and characterization

The introduction of solvent-free nanofluids composed of suitably surface functionalized nanoparticles (nanosilica for example) has led to some interesting new materials. Here we show that the process of surface functionalizing with both nanofluid-inducing surface groups and with reactive (acrylate) surface groups produces solvent free nanofluids that can be incorporated in reactive coatings, films, and bulk materials and composites. We demonstrate in this study some composite materials based on our new reactive acrylate-nanofluid and a commercially available tetraacrylate. While it is widely known that addition of fillers and nanoparticles to resins often produces increased storage and elastic moduli, while generally also increasing brittleness, we found in this study that increasing weight fractions of reactive nanofluid in an otherwise very brittle environment, produces materials that are tougher (softer) while maintaining or decreasing storage moduli (depending on whether the loading is small or large). Possible applications include a new class of clearcoat protective overcoats and interesting new materials where softness is a formulation variable, such as in plasticization. In addition, we demonstrate that nanocomposites at high loading may be made thermally responsive in ways the parent polymer matrix is not. AFM surface analyses show that the nanofluid particles exhibit surface activity at the air–polymer interface similar to that observed for interfacial nanoparticles in Pickering emulsions. This surface activity, along with the intrinsic softness of the nanofluid particles, may offer a simple approach to providing intrinsic lubrication for polymeric surfaces subject to frictional shear.