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In this study, carbon papers and aerogels were prepared from chitosan and graphene layers with aldehydic edge functional groups (G-CHO) able to form chemical bonds with chitosan and thus to form a crosslinked network. A high surface area graphite was edge functionalized with hydroxyl groups (G-OH) through the reaction with KOH. G-CHO, with 4.5 mmol/g of functional group, was prepared from G-OH by means of the Reimer-Tieman reaction. Characterization of the graphitic materials was performed with elemental analysis, titration, X-ray analysis, Raman spectroscopy and by estimating their Hansen solubility parameters. CS and G-CHO were mixed with mortar and pestle and carbon papers and aerogels were obtained from a stable acidic water suspension through casting and liophilization, respectively. Free standing and foldable carbon papers and monolithic aerogels based on a continuous covalent network between G-CHO and CS were prepared. G-CHO, which had about 22 stacked layers, was extensively exfoliated in the carbon paper, as confirmed by the absence of the 002 reflection of the graphitic crystallites in the XRD pattern. Carbon paper was found to be resistant to solvents and to be stable for pH ⩾ 7. Composites revealed electrical conductivity. The covalent network between the graphene layers and CS, suggested by the IR findings, accounts for these results. This work demonstrates the effectiveness of a continuous covalent network between chitosan and graphene layers edge functionalized with tailor made functional groups for the preparation of carbon papers and aerogels and paves the way for the scale up of such a type of composites.

In the recent years, significant interest on the production, characterization and application of cellulose nanofibers has brought out among scientific and technic authorities. This special attention mainly comes from their biodegradability, renewability and versatility, making them able to be used for several applications and fields. This topic outbreak took place about ten years ago, fact that is confirmed by the exponential increase on scientific publications and patents since then. In a nutshell, the present thesis aims to demonstrate that enzymatically hydrolyzed cellulose nanofibers can be successfully produced and used in several sectors. Their versatility, availability, low cost and low environmental impact justify the ongoing research in this field, En els darrers anys, entre la comunitat científica i tecnològica s’ha despertat un gran interès en la producció, caracterització i utilització de nanofibres de cel·lulosa. Aquesta especial atenció es deu, principalment, al seu caràcter biodegradable, el seu origen renovable i la versatilitat que presenten, fent-les aptes per ser utilitzades en multitud d’aplicacions. L’esclat d’aquesta temàtica de recerca va tenir lloc aproximadament deu anys enrere, doncs només cal observar el creixement exponencial de publicacions científiques i patents des d’aleshores. De manera general, la present tesi pretén demostrar que les nanofibres de cel·lulosa obtingudes mitjançant un pretractament d’hidròlisi enzimàtica poden ser produïdes de forma efectiva, de manera que pugin ser aplicades en una gran varietat de camps científics i tecnològics. La seva gran versatilitat, disponibilitat, baix cost i baix impacte mediambiental, justifiquen que en el futur es continuï amb la seva investigació sobre noves aplicacions

Point-of-care devices that are inexpensive, disposable, and environmentally friendly are becoming increasingly predominant in the field of biosensing and biodiagnostics. Here, microfluidics is a suitable option to endow portability and minimal reagent and material consumption. Nanocellulose is introduced to manufacture microfluidic channels and as a storage and immobilization compartment of glucose oxidase. Improved enzymatic activity retention is demonstrated in a simple and disposable point-of-care diagnostic unit that is able to detect glucose from fluid matrices at 0.1 mM concentration and in less than 10 min. It is concluded that the patterning and fluidic technologies that are possible with nanocellulose enable easily scalable multianalyte designs. publishedVersion