As bioelectronics continue to evolve, one concern is their fate once they reach the end of their intended purpose. Transient electronics designed with programmable degradation may remedy this concern while also offering opportunities to advance their performance for targeted applications. Organic semiconducting polymers are uniquely suited for these applications due to their tuneable mechanical, physical, and degradable properties, versatile synthesis and potential for biocompatibility. A notable example is my group’s work using
β-carotene derivatives (pigments found in carrots and other organic matter) in the synthesis of degradable biocompatible semiconducting polymers. β-carotene derivatives were selected for these applications because they exhibit high single-molecule conductance and are structurally similar to polyacetylene, a canonical electron conducting polymer in the field. Additionally, they are abundant and have well-established degradation pathways in the human body, making them affordable and non-toxic alternatives to conventional conducting materials. In initial studies, a β-carotene based dialdehyde was co-polymerized with a commercially available para-substituted diamine to generate semiconductive polymers with acid-labile imine linkages. However, the polymers had non-linear morphologies due to their para-propagations, contributing to poor crystalline packing, subsequent low conductivity and undefined degradation kinetics—factors that currently restrict their use in modern bioelectronics. This work aims to optimize the morphology of the polymers to generate linear and crystalline polymers with improved electron conducting properties and controlled degradation rates. Overall, this work seeks to advance the use of β-carotene in degradable electronics while also broadening our understanding of how polymer morphology impacts electron transport properties.

The synergistic combination of hard polyacrylate (PAc) and soft polyurethane (PU) leads to an important class of hybrid materials suitable for various waterborne coating applications [1]. In such colloidal dispersions and cast films, the PU phase enhances film formation, flexibility, and toughness, while the incorporation of PAc improves mechanical properties and outdoor resistance[2]. Although extensive research has focused on the effect of PAc content on the final properties of PAc@PU hybrid films [1], to our knowledge, no studies have elucidated its influence on the nanoscopic structural development during the drying process.
In this study, we present a detailed in-situ and ex-situ investigation of industrially relevant PAc@PU hybrids with varying PAc compositions (0 wt.%, 10 wt.%, 30 wt.%, and 50 wt.%). Our results reveal that introducing a low amount of PAc phase into the PU matrix does not have a significant impact on the drying process during the particle concentration and packing phase, even though the formation of water channels with different thicknesses alters the water evaporation kinetics during particle coalescence and impacts the total drying time of the system. On the contrary, when a high amount of PAc is present (50 wt.%), the onset of the particle coalescence is significantly delayed, and the coalescence process is dramatically slowed down. This work also shows that incorporating the hard PAc leads to higher surface stiffness, which prevents skin break-up, thus leading to better structural integrity. Finally, we demonstrate that the PAc phase significantly influences PU chain clustering behavior during drying.

Plastic debris from fishing and aquaculture activities has been identified as a major contributor to pollution of the marine environment (Macfadyen et al., 2009). Discarded, lost or abandoned fishing gear persists in the ocean for extended periods, resulting in ghost fishing and harm to marine ecosystems through the release of substantial quantities of microplastics (Gilman, 2015). The utilisation of biodegradable polymers in demersal fisheries could be a superior alternative to conventional polymer materials, as has been demonstrated previously (Grimaldo/Karl et al, Marine Pollution Bulletin, 2023).
To address this issue, a program of controlled laboratory experiments, as well as field testing of biodegradable fishing gear (PBSAT monofilaments) is conducted, using non-biodegradable polyamide (PA) as control. The laboratory setup includes accelerated ageing experiments, and the field experiments will be conducted under different marine environmental conditions to study physical, chemical and microbiological degradation over an extended test period. The degradation of biodegradable PBSAT polymer monofilaments and conventional polyamide (PA6) has been studied after accelerated ageing using surface characterization methods, FTIR and NMR spectroscopy, mechanical testing and friction as well as wear experiments (Karl et al., 2025). In the field, marine (bio)degradation of PBSAT- and PA-monofilaments are tested in situ in different marine habitats (Skagerrak Sea, North Sea, Baltic Sea, Adriatic Sea, and Norwegian Sea), to cover a wide range of environmental conditions. The quantification of physical, chemical and microbial degradation is achieved through a series of rigorous tests, including mechanical properties, SEM, pyrolysis-GC-MS and microbial community analysis (Hakvåg et al, in preparation).

“Smart materials“ has garnered significant interest due to their ability to undergo a response to external stimuli, thereby altering their inherent properties. This property can be specifically applied to surfaces through the coating of these surfaces with responsive polymer brushes. A substantial body of research has been dedicated to studying the responsiveness of polymer brushes to various stimuli, including changes in temperature, pH, salt concentration, light, and electric or magnetic fields. However, the field of electrochemical switching of polymer brushes, which offers advantages such as fast switching rates and resistance to external sources of interference, has received comparatively less attention, despite its potential applications in sensors, nanoactuators, and biomedicine.
The objective of this study is to investigate the electrochemical switching behavior of poly-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PMETAC) polymer brushes. While not electroactive themselves, the brushes exhibit responsive behavior in ferricyanide solutions through electrochemically-induced complexation. By applying electric potentials, it is possible to oxidize/reduce the ferrocyanide/ferricyanide redox pair, which in turn interact differently with the PMETAC polymer brushes and lead to their collapse or swelling. To thoroughly examine this phenomenon, two distinct approaches were employed: ellipsometry and electrochemical QCM-D. These methods were utilized to analyze the behavior under varying ferricyanide concentrations, offering varied insights into the underlying processes. Furthermore, the impact of polymer brush architecture and layer structure on these processes was investigated by preparing brushes with different PMETAC polymers and employing grafting techniques.

Hydrogels composed of polysaccharides and peptides are widely recognized for their ability to partially mimic the native extracellular matrix (ECM), providing a biomimetic environment that supports and promotes cell processes. Recent research has underscored that not only these hydrogels’ stiffness (represented by their storage modulus (G’)) but also their stress relaxation, i.e., the ability of a substrate to dissipate cell-induced forces (represented by relaxation time (τ)) influence cells’ functions. And thus,
the dynamic stress-strain behavior should be modulated to optimize hydrogel performance for applications as 3D cell scaffolds.
Our research aims to develop multicomponent hydrogels that will retain macroscopic stability while modeling the microscopic dynamics of native ECM and allow orthogonal control of their relaxation time and elasticity.
To that end, we have been developing a double network hydrogel consisting of a primary network of modified alginate, chemically crosslinked through hydrazone bonds between dialdehyde and adipic acid dihydrazide; Coupled with self-assembling switch peptides that form a secondary physical network only after a specific enzyme triggers a linearization of these depsipeptides to a b-sheet forming sequence.
Detailed investigation of the interplay between their viscoelastic properties and their nanostructure (characterized by SAXS , cryo-TEM, and cryo-SEM) shows that the crosslinking ratio, peptide: polymer ratio, and peptide sequence all influence the capacity to independently regulate the relaxation time and elasticity of these multi-component hydrogels.

Microcontact printing (µCP) is a widely used soft lithography technique for microscale patterning of surfaces with functional molecules.[1] This technique can be used to transfer reactive molecules to pattern various substrates via direct contact. Predominantly, smooth metal surfaces are patterned using µCP with high precision,[2] while capillary-active hydrophilic surfaces are not the subject of µCP, since reactive ink molecules smear on the substrate due to ink diffusion, resulting in inaccurate patterns with poor resolution.
To overcome this limitation, we introduced a polymer-brush-assisted µCP method. [3, 4] In this approach, polymer brushes are grafted onto the patterned stamp surface, immobilizing small ink molecules and facilitating their transfer to the substrate through covalent interactions restricting possible ink diffusion to enable precise surface patterning.

This technique has been successfully used to precisely pattern soft glycosylated microgels and human cells [5] as well as rough, capillary-active oxidic surfaces [4] by leveraging specific interactions between functional ink molecules and substrate surface-active groups.

In the last decades, propagation rate coefficient (kp) values became available for a number of homopolymerization and copolymerization systems using pulsed laser polymerization combined with size-exclusion chromatography. Previous studies on the aqueous-phase polymerization kinetics of water-soluble monomers have shown that kp values depend on monomer type, monomer concentration, solvent composition, monomer conversion, ionic strength, pressure, temperature, pH, and degree of ionization.[1] However, the data for sparingly water-soluble monomers, i.e., monomers exhibiting low solubility in water such as methyl acrylate (MA), 2-methoxyethyl acrylate (MEA), and methyl methacrylate (MMA) remained limited. For MA and MEA, kp values have been explored only under limited conditions in water and alcohol/water mixtures [2], whereas, no such data exist for MMA.

Herein, we investigated kp values for these sparingly water-soluble monomers as a function of monomer concentration, solvent composition (water, ethanol/water mixtures), and temperature. To highlight, kp values for 1.2 wt% MEA, MA, and MMA in water are 9, 15, and 40 times higher, respectively, compared to bulk kp values. The kp values increased as the MEA concentration in water decreased between 10 and 1.2 wt%, whereas no variation in kp values is seen between 1.2 and 5 wt% MA concentrations. Increasing the water content in ethanol/water mixtures results in increased kp values. Overall, this study provides the first-ever information on polymerization of this class of monomers in water and ethanol/water mixtures.