Structure and dynamics of bio-inspired polymer networks

Supramolecular bonds, such as hydrogen bonds, pi-pi stacking, and host-guest interactions, refer to weak, transient bonds that can form temporary associations. Polymers containing supramolecular moieties exhibit drastically changed physical properties due to these reversible associations. These supramolecular polymers have a wide range of applications, including self-repairing elastomers, artificial tissues, and protective coatings. Adding supramolecular groups to a bulk polymer matrix alters both the structure and dynamics at the molecular level. Since macroscopic properties differ accordingly, it is crucial to combine fundamental polymer physics with the effects of supramolecular groups. Understanding the influence of these groups enables better design of functional materials. The design of a dual network with both transient and permanent crosslinks provide deep insights into the relationships among relaxation, entanglements, and crosslinks. To prevent complicated relaxation mechanisms from phase-separated polymers, homogeneous supramolecular-polymer pairs are used. In this work, PBO with Thy-DAT pairs form a homogeneous mixture where the relaxation of individual strands is not affected by clusters of supramolecular groups. Long backbone polymer chains are copolymerized randomly with reaction sites capable of thymine addition and thiol-ene crosslinking reactions. These long backbone chains are mixed with short telechelic DAT-functionalized polymers. The resulting polymer architecture forms a complex TN. The relaxation dynamics of TN correlate with dynamic dilution and sticky reptation theories, showing unique viscosity behavior by combining the analysis of dielectric spectroscopy and rheology. The photo thiol-ene click reaction between the backbone polymers forms a material with additional stable permanent crosslinks, known as the DN. Introducing crosslinks influences relative motion, highlighting the increased activation energy of transient bonds. Further structural studies of the DN are conducted using X-ray methods. For the DN, different temperatures reveal varying numbers of association pairs observable by SAXS and analysis within the RPA, considering the short telechelic polymer as an A-B-A triblock. To investigate the extension limits of hydrogen bonds while stretching the polymer, in situ SAXS measurements at low temperatures are performed. Correlations between the parallel stretching direction of the strain and its RPA peak shifts are obtained. The experimental setup demonstrates a way to visualize the capability of transient bonds in continuously extending polymers. The last part of the thesis focuses on the properties of the telechelic polymer DAT-PBO5k-DAT. The dynamics and structures differ from the TN due to head-to-head linear extension associations. The structure remains homogeneous, yet the viscosity profile is complex, showing higher plateau moduli than non-functionalized long backbone polymers. The rheology curve can be explained using the adapted sticky Rouse model and numerical approaches.