In the Mommer Research Group, we seek to engineer polymeric materials that vary from soft, stretchable (e.g. tough hydrogels) over to polymer-based solvent-free materials (thermoplastics or elastomers). We combine various disciplines such as organic, polymer and supramolecular chemistry, as well as material science and engineering. A special focus is laid on the link between the molecular features and the resulting mechanical properties of the materials (structure-property relationships) as well as on material sustainability. The latter can be tailored and improved through durability (robust materials with long life-times) or degradability (on-demand degradation), especially regarding thermoplastic polymer materials.
Durable Tough Hydrogels
Hydrogel materials are crosslinked polymer networks with reversible swelling, tunable porosity, elasticity, toughness, and flexibility. Conventional hydrogels often suffer from weak mechanical properties and display brittle and unstable behavior limiting their scope for load-bearing applications. This shortens their lifetimes, requiring replacement, ultimately decreasing material sustainability.
We are interested in the molecular design of high-performance hydrogels with toughness and elasticity similar to rubber and applications towards durable medical materials and high-performant responsive materials.
Next to other cross-linking strategies (see Figure), we predominantly exploit supramolecular strategies to dissipate energy throughout the polymer networks making our materials often self-healing and self-recoverable. We do so by incorporating host-guest interactions (i) as transient reversible cross-links that disengage and reform upon the application of stress and (ii) as slidable cross-links in the main polymer chain creating a unique slide-ring architecture. The latter consists of movable cross-links, which once a mechanical impact is applied, can freely translocat along the polymer backbone to equalize tension. Such a topology can infuse materials with unique physicochemical and mechanical properties, such as large volume changes during equilibrium swelling, enhanced stretchabilities, highly elastic response to deformation, and increased elastic moduli as compared to conventional hydrogels.
Sustainable Polymer Materials
Within this research line, we seek to develop new strategies for the preparation of degradable, yet durable polymeric materials that can satisfy both short and long lifetimes. On short timescales, the polymers are engineered to allow for an on-demand degradation, which is designed to counteract the growing environmental pollution through single use plastics (SUPs), the majority of which exhibit extremely long degradation times and to this day lack efficient recycling and practicable end-of-life treatment options.
To the contrary, performance plastics require consistent mechanical properties and high durability, yet often experience aging during their extended life span. To mitigate aging effects, we investigate materials that are able to self-heal and self-reinforce as a result of said aging. This effect is based on the polymer’s unique internal structural features and therefore, does not require any chemical additives. Durability and longevity of the corresponding polymers are thus, increased, minimizing the need for replacement. This process is independent from the material’s ability to degrade in a controlled environment, therefore adhering to the promise of enabling end-of-life treatment options.
Both scenarios (short and long lifetimes) represent an inherent conflict between on-demand (bio)degradability and durability and we strive to address this challenge by developing polymer materials that satisfy both SUPs and performance plastics, reconciling degradability with mechanical durability.
If you are interested to work with us on cutting-edge (soft) materials, we invite you to check out the Vacancies section for open positions!