This thesis explores the optimization and design of novel materials by engineering interfaces to impart novel mechanisms to polymer composites and multi-phase materials. By taking advantage of chemical and mechanical interactions it is possible to create materials with novel properties and unique mechanisms such as self-stiffening, self-healing, and adhesion. These properties arise due to large electronegativity differences which are repeated throughout the polymer chains which in turn give rise to strong macroscopic effects. The addition of a dynamic interface, an interface which can move and adapt under varying stress conditions, further enhances the unique properties of these materials. The composites discussed in this thesis were synthesized using a variety of techniques including thermal sonication/chemical synthesis, and mechanical synthesis. These novel composites were characterized using a myriad of techniques such as dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray computerized tomography (CT), in-situ scanning electron microscopy-based (SEM) mechanical testing, tensile testing (ADMET frame), SEM, transmission electron microscopy (TEM), contact angle (CA), optical microscopy, and qualitative testing.