In this study an optical cellulose fiber for water sensoring was prepared by using a sequential preparation strategy. The core of the fiber was prepared from dissolved cellulose, in [EMIM]OAc, which was dry–wet spun into water. The cladding layer on the cellulose core was produced by coating a layer of cellulose acetate, dissolved in acetone, using a filament coater. The chemical and optical properties of both regenerated cellulose and cellulose acetate were studied from cast films using ultraviolet–visible and Fourier-transform infrared spectroscopy measurements. Regenerated cellulose film was observed to absorb UV light, passing the visible light wavelengths. Cellulose acetate film was observed to pass the whole light wavelength range. The mechanical strength and topography of the prepared optical cellulose fiber were investigated through tensile testing and SEM imaging. The mechanical performance of the fiber was similar to previously reported values in the literature (tensile strength of 120 MPa). The prepared optical fiber guided light in the range of 500–1400 nm. The attenuation constant of the cellulose fiber was observed to be 6.3 dB/cm at 1300 nm. The use of prepared optical cellulose fiber in a water sensor application was demonstrated. When the fiber was placed in water, a clear attenuation in the light intensity was observed. The studied optical fiber could be used in sensor applications, in which easy modifiability and high thermal resistance are beneficial characteristics. Graphic abstract Coaxial cellulose acetate-regenerated cellulose fiber for transporting light in sensor optical fiber sensor applications.

In this study, we investigated the enzymatical degradability and pilot-scale composting of 14 cellulose-based materials. The materials analyzed here were cellulose regenerated from ionic liquid (EMIM[OAc]), carboxymethyl cellulose (CMC) crosslinked by aluminum salt (Al-salt), methyl cellulose, cellulose acetate, butylated hemicellulose: DS: 1, DS: 0.4, and DS: 0.2, cellophane, wet strength paper, nanocellulose, paper partially dissolved by IL, cellulose carbamate, cellulose palmitate, and cellulose octanoate. The aim of the study was to show how chemical substituting and the substituent itself influence the biodegradability of cellulose materials. The enzymatic degradation and pilot-scale composting of these films shows the correlation between the hydrolysis rate and degree of substitution. The enzymatic hydrolysis of cellulose-based films decreased exponentially as the degree of substitution increased. Modifying cellulose to the extent that it gains the strength needed to obtain good mechanical properties, while retaining its natural biodegradability is an important factor when preparing alternatives for plastic films.

Four different types of crystalline and fibrillar nanocellulosic materials with different functional groups (sulfate, carboxylate, amino-silane) are produced and used to disperse commercial multiwalled carbon nanotubes (MWCNT). Aqueous nanocellulose/MWCNT dispersions are drop-cast on tetrahedral amorphous carbon (ta-C) substrates to obtain highly stable composite electrodes. Their electrochemical properties are studied using cyclic voltammetry (CV) measurements with Ru­(NH3)6 2+/3+, IrCl6 2–/3– redox probes, in electrolytes of different ionic strengths. All studied nanocellulose/MWCNT composites show excellent stability over a wide potential range (−0.6 to +1 V) in different electrolytes. Highly anionic and more porous fibrillar nanocellulosic composites indicate strong electrostatic and physical enrichment of cationic Ru­(NH3)6 2+/3+ in lower-ionic-strength electrolytes, while lesser anionic and denser crystalline nanocellulosic composites show no such effects. This study provides essential insights into developing tailorable nanocellulose/carbon nanomaterial hybrid platforms for different electrochemical applications, by altering the constituent nanocellulosic material properties.

Microplastics accumulate in various aquatic organisms causing serious health issues, and have raised concerns about human health by entering our food chain. The recovery techniques for the most challenging colloidal fraction are limited, even for analytical purposes. Here we show how a hygroscopic nanocellulose network acts as an ideal capturing material even for the tiniest nanoplastic particles. We reveal that the entrapment of particles from aqueous environment is primarily a result of the network’s hygroscopic nature - a feature which is further intensified with the high surface area of nanocellulose. We broaden the understanding of the mechanism for particle capture by investigating the influence of pH and ionic strength on the adsorption behaviour. We determine the nanoplastic binding mechanisms using surface sensitive methods, and interpret the results with the random sequential adsorption (RSA) model. These findings hold potential for the explicit quantification of the colloidal nano- and microplastics from different aqueous environments, and eventually, provide solutions to collect them directly on-site where they are produced.

Polymer composites with nanocellulose as the reinforcing agent often lack good compatibility between the two components. In this study, we have combined cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) in different ratios to create all-cellulose films consisting of entirely discrete nanocellulose objects that complement each other. Then further, by applying the controlled dissolution concept we were able to create defined optical patterns on the films. The films consisting of 50% CNCs showed equivalent mechanical and barrier properties when compared to the pure CNF film. In addition, the incorporation of CNCs enabled tuning of the films’ optical properties. To modify this film further, we prepared specific patterns on the film by controlled dissolution by impregnating the films with N-methylmorpholine-N-oxide (NMMO) followed by heat treatment and pressure. Mechanical testing and optical measurements of the patterned films showed the effect of the dissolved cellulose regions on the film properties. The controlled dissolution of the films increased the tensile strength of the films, however, the strain was decreased quite significantly. Altogether, the CNF/CNC hybrid films combine both nanomaterials’ good properties. Cellulose nanofibrils have film-forming ability and incorporation of CNCs can further tune the optical, mechanical, and barrier properties, to optimize the films for varying applications such as optical sensors and packaging materials. Graphical abstract