Cellulose acetate (CA) is an established commercial material based on an inherently biodegradable biobased resource, cellulose. However, chemical modification through acetylation to obtain thermoplastic properties significantly limits the biodegradation rate, making deacetylation the rate-determining step for subsequent biodegradation. We developed an innovative approach by immobilizing lipase (IL) enzymes on cellulose nanocrystals (CNCs), and embedding the resulting CNC-IL into CA films to accelerate the biodegradation of CA. This offers a platform for controlling and accelerating the degradation of CA, as demonstrated by significantly enhanced degradation rates under self-degradation and enzymatic degradation in aqueous medium, including artificial seawater, and under simulated industrial composting conditions. We also explored the underlying mechanisms by detailed characterization of the degradation process in different degradation environments, demonstrating that the enzyme-embedded approach and utilization of CNCs as an immobilization matrix holds significant promise for catalyzing the biodegradation process by initiating self-degradation from inside the polymer material. This approach thus holds promise in accelerating the degradation process and ensuring degradation even under less favorable environmental conditions.

Environmental pollution by release of nondegradable textile fibers and single-use fabrics, such as face masks, is a serious threat. Replacement of electrospun polypropylene fabrics with materials that have a better environmental degradation profile is therefore of interest. Here, a strategy is presented through carbon dot (CD) modification of cellulose acetate (CA) mats produced by a one-step electrospinning process. The mats were carefully characterized for their physicochemical properties and screened for any antioxidant or antibacterial properties before they were subjected to aging under UV irradiation or soil burial. Typically, the degree of substitution (DS) of CA needs to be under 2 for any significant biodegradation to take place. It was therefore of interest to notice that some deacetylation took place already during electrospinning as the initial DS of 2.2, as determined by nuclear magnetic resonance spectroscopy (NMR), decreased to 2.0 and 1.8 for CA and CD-modified CA (CA-CD), respectively. After 30 days of soil burial or 7 days of UV irradiation, the DS of CA-CD had further decreased to 1.1 and 0.9, while the corresponding values for plain CA were 1.5 and 1.8. CD modification thus significantly catalyzed the deacetylation process, helping to overcome the bottleneck of CA biodegradation. The degradation of the mats was supported by other physicochemical changes, such as decreased water contact angle and molecular weight values. It was further shown that degradation during soil burial was significantly faster for the electrospun mats compared to the corresponding CA and CA-CD films, which could be due to the combination of larger surface area and the deacetylation that took place during electrospinning, making the electrospun mats more susceptible to subsequent biodegradation. However, the catalyzing effect of CD was observed even for the film samples, leading to somewhat lower DS and higher mineralization as determined by CO₂ release.

Embedding immobilized lipase (IL) enzymes into polycaprolactone (PCL) matrix was demonstrated as a promising route to faster biodegradable and chemically recyclable PCL products. Furthermore, the materials could be thermally processed by extrusion and 3D printed by fused filament fabrication technique. The embedded-enzymes were shown to effectively accelerate the degradation of PCL under simulated industrial composting conditions and in aqueous solution in combination with external enzymes. To reveal deeper insights into the underlying mechanisms, the biodegradation kinetic parameters governing organic carbon (OC) mineralization were calculated. Furthermore, the concept of biodegradation half-life (B1/2) was introduced and correlated with the organic carbon (OC) mineralization rate of enzyme-embedded PCL films and filaments, especially under thermophilic composting conditions. This sheds light on how the incorporation of immobilized enzymes into PCL facilitates the degradation process. Furthermore, the feasibility of enzyme-catalyzed chemical recycling under mild conditions followed by enzyme-catalyzed repolymerization was demonstrated. The applied material design principle holds promise for addressing the pressing challenges associated with plastic waste, when moving forward towards a more sustainable and environmentally conscious future.

Cellulose-derived materials could offer more sustainable alternatives for current single-use hygiene articles produced from nondegradable fossil-based polymers. We successfully fabricated light processable methacrylated carbon dot-hydroxyethyl cellulose resins and illustrated potential applications in dye adsorption, antibacterial gels, and wet wipes. Carbon dots were first produced by microwave-assisted hydrothermal carbonization and the oxidation of cellulose. The obtained carbon dots and hydroxyethyl cellulose were in situ methacrylated to composite resins, which could be cured to gels in a mold or processed to 3D structures with digital light processing 3D printing. The cured gels had an adequate gel content of 80-84% and high swelling degree up to 350% in binary mixtures of water and dimethyl sulfoxide. Furthermore, the gels were effective dye-adsorbents, and they retained some of the antibacterial properties of nonmodified hydroxyethyl cellulose as evaluated by the disc diffusion method. While the gels could still be recovered after 60 days of soil burial at room temperature, clear sign of degradation and opening of the cross-linked structure were observed by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Finally, a potential wet wipe was fabricated by laminating the produced gel between two electrospun cellulose acetate mats.

A simple non-equilibrium atmospheric plasma post-treatment strategy was developed for the surface coating of three-dimensional (3D) structures produced by digital light processing 3D printing. The influence of non-equilibrium atmospheric plasma on the chemical and physical properties of vanillin-derived Schiff-base thermosets and the dip-coating process was investigated and compared to the influence of traditional post-treatment with UV-light. As a comparison, thermosets without post-treatment were also subjected to the coating procedure. The results document that UV post-treatment can induce the completion of the curing of the printed thermosets if complete curing is not reached during printing. Conversely, the plasma post-treatment does not contribute to the curing of the thermoset but causes some opening of the imine bonds and the regeneration of aldehyde functions. As a consequence, no great differences are observed between the not post-treated and plasma post-treated samples in terms of mechanical, thermal, and solvent-resistant properties. In contrast to the UV post-treatment, the plasma post-treatment of the thermosets induces a noticeable increase of the thermoset hydrophilicity ascribed to the reformation of amines on the thermoset surface. The successful coating process and the greatest uniformity of the lignosulfonate coating on the surface of plasma post-treated samples are considered to be due to the presence of these amines and aldehydes. The investigation of the UV shielding properties and antioxidant activities documents the increase of both properties with the increasing amount and uniformity of the formed coating. Interestingly, evident antioxidant properties are also shown by the noncoated thermosets, which are deduced to their chemical structures.