Ronald Zirbs

The development of sustainable polymer materials is a major challenge, driven by the increasing demand for environmentally sustainable alternatives to conventional plastics.

The growing need to reduce plastic waste has prompted the development of bio-based and biodegradable materials. Cellulose is attracting increasing attention as a sustainable filler candidate due to its renewability, abundance, and favorable mechanical properties. Its application in polylactic acid (PLA)-based composites has been extensively studied and has demonstrated improvements in mechanical strength, barrier properties, and processability. However, the use of nanocellulose in other biodegradable polymers such as poly(butylene succinate) (PBS) and poly(butylene adipate-co-terephthalate) (PBAT) remains limited, despite their industrial significance. In this study, we developed matrix-adapted cellulose nanoparticles by grafting PBS or PBAT onto cellulose regenerated from aqueous sodium hydroxide solution. Grafting was carried out via melt polycondensation, resulting in nano-sized particles with average sizes of approximately 100 nm for PBS and 175 nm for PBAT. These surface-modified particles exhibited improved thermal stability and high polymer content, reaching 25 wt% for PBS and 50 wt% for PBAT, indicating successful grafting, which is expected to facilitate compatibility with the target biodegradable matrices. This work provides a new approach for the rational design of biodegradable nanocomposites beyond PLA and contributes to the development of sustainable high-performance materials.

The incorporation of modified bacterial cellulose derived from agricultural waste improves biodegradable composites by reducing oxygen permeability and accelerating biodegradation while maintaining mechanical properties.

The need to switch to bio-based, biodegradable and/or fully recyclable polymers is becoming increasingly clear, especially in the area of food packaging, which is a major contributor to plastic pollution. To meet this challenge, biodegradable polymers must not only be economically viable, but also have properties that match or better those of conventional fossil-based polymers, such as robust mechanical strength and efficient gas barrier properties. One promising route is the production of composite materials from biodegradable polymers and SiO₂ nanoparticles. However, the high surface energy of SiO₂ often leads to agglomeration of the filler in the hydrophobic polymer matrix, which compromises the integrity of the composite. Here we present an innovative approach in which the surface of silica nanoparticles is modified with L-lactic acid oligomers (OLLA), effectively reducing the agglomeration of the filler and improving processability. Using conventional polymer processing methods that comply with industry standards, we prepared PLLA and PHBV nanocomposites and evaluated the effectiveness of the modification using a novel SBF-SEM technique. Our results show that modified silica achieves better dispersion in the polymer matrix and yields 70% more independent particles in the nanocomposite. The introduction of OLLA-g-SiO₂ increases the oxygen barrier of PLLA by 38% while accelerating the biodegradation rate and improving the toughness of the eco-friendly nanocomposites. This innovative approach offers a sustainable solution that is set to revolutionise the landscape of green food packaging.

Coating processes are commonly used in materials science to protect a core or modify material properties. We describe a hydrothermal coating process using TEOS (tetraethyl orthosilicate), a widely used precursor for silica coatings, on three representative template materials (carbon nanotubes, silica, and polystyrene nanoparticles) with different properties and shapes. We compare the efficiency of previously published protocols for silica coatings at room temperature and atmospheric pressure with the hydrothermal process at 160 °C and 3 bar. The hydrothermal method achieves higher yields and thicker silica coatings with the same amount of precursor when compared to the conventional way, thus offering higher effectiveness. Furthermore, the hydrothermal coating process yields more homogeneous shells with a higher density, making hydrothermal coating the method of choice when mechanical integrity and low permeability of the coating are required.

Thermoresponsive nanoparticles are promising smart materials for many applications. However, a rational design for applications requires a deeper understanding and experimental verification of the various parameters that influence the thermoresponsiveness of the spherical polymer brushes that define most of such nanomaterials. Therefore, we investigate superparamagnetic iron oxide nanoparticles (SPION) grafted with poly(2-isopropyl-2-oxazoline) (6–33 kg mol⁻¹) by temperature-cycled dynamic light scattering and differential scanning calorimetry. The grafting of dense spherical polymer brushes leads to lower aggregation temperatures and transition enthalpies when compared with the free polymer. The transition enthalpy and temperature depend on the polymer shell size and structure. The addition of kosmotropic salts decreases the aggregation temperature following the Hofmeister series.

Crosslinked colloidal monolayers are promising as templates, lithographic masks, filtration membranes, or membranes for controlled release rates in drug de

Thermoresponsive polypeptoids are promising candidates for medical applications due to their biomimetic properties. When such polymers are grafted on magnetic nanoparticles, materials can be obtained that combine a temperature‐triggered solubility transition with magnetic extraction. The synthesis of monodisperse, superparamagnetic iron oxide nanoparticles is described with densely surface‐grafted polypeptoid shells that have tunable thermoresponsive colloidal stability. The synthesis combines ligand exchange with controlled surface‐initiated polymerization of N‐substituted N‐carboxyanhydrides for the preparation of well‐defined core–shell nanoparticles. image

Emerging biomedical applications such as molecular imaging and drug delivery often require directed binding of nanoparticles to cell-membrane receptors. The specific apparent affinity of such ligand-functionalized particles is size-dependent, an observation so far solely attributed to multivalent receptor–ligand interaction. We question the universality of this explanation by demonstrating that the binding kinetics also depends on weak, attractive colloidal-type interaction between nanoparticles and a lipid membrane. Applying label-free single-particle imaging, we correlate binding of nanoparticles targeted to a cell-mimetic lipid membrane with the distribution of nontargeted particles freely diffusing close to the membrane interface. This analysis shows that already a weak, k_BT-scale attraction present between 50 nm gold nanoparticles and the membrane renders these particles an order of magnitude higher avidity compared to 20 nm particles. A stronger emphasis on nonspecific particle–membrane interaction might thus be required to accurately predict nanoparticle targeting and other similar processes such as cellular uptake of exosomes and viruses.