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The master's thesis deals with the determination of macroscopic behavior of a particulate composite with cross-linked polymer matrix under tensile load. The main focus of thesis is estimation of mechanical properties of a composite loaded by tensile loading using numerical methods (especially finite elements method). Investigated composite is composed of matrix in a rubbery state filled by alumina-based particles (Al2O3). Hyperelastic properties of the matrix have been modeled by the Mooney-Rivlin material model. Different compositions of particles, their different shape, orientation and different volume fractions have been considered. For all these characteristics of composite numerical models have been developed. The damage mechanisms of the matrix have also been taken into account. Results of numerical analyses have been compared with experimental data and good agreement between numerical models with damage mechanisms of matrix and experimental data has been found.

The design and engineering of nanoscopic drug delivery vehicles that stably encapsulate lipophilic drug molecules, transport their loaded cargo to specific target sites, and release their payload in a controlled manner are of great interest in therapeutic applications, especially for cancer chemotherapy. This dissertation focuses on chemically cross-linked, water-soluble polymer nanoparticles, termed nanogels, which constitute a promising scaffold and offer the potential to circumvent encapsulation stability issues. A facile synthetic method for a new class of self-cross-linked polymer nanogels, synthesized by an intra/intermolecular disulfide cross-linking reaction in aqueous media, is described here. This simple emulsion-free method affords noncovalent lipophilic guest encapsulation and surface functionalization that may allow for targeted delivery. The encapsulation stability of lipophilic molecules sequestered within these nanoscopic containers is evaluated by a fluorescent resonance energy transfer (FRET) based method developed by our research group. We demonstrate that the encapsulation stability of noncovalently encapsulated guest molecules in disulfide cross-linked polymer nanogels can be tuned and that guest release can be achieved in response to a biologically relevant stimulus (GSH). In addition, varied hydrophobicity in the self-cross-linked nanogels affects the lipophilic loading capacity and encapsulation stability. We reveal that optimal loading capacity is limited by encapsulation stability, where over-loading of lipophilic molecules in the nanoscopic containers may cause undersirable leakage and severely compromise the viability of such systems for drug delivery and other biological applications.