The aim of the present study is to investigate the effect of the hydrolysis process on the properties of nanocrystalline cellulose (NCC) isolated from different precursors and the subsequent use of the extracted NCC for the reduction of graphene oxide (GO). The raw materials (almond and peanut shells) chosen for the isolation of cellulose were selected on the basis of their abundance and their poorly investigation in the production of NCC. Microcrystalline cellulose (MCC) was firstly extracted by alkali and bleaching treatments, then hydrolyzed under different processes to produce NCC polymorphs with structure I (NCC-I) and NCC structure II (NCC-II). The Fourier transform infrared spectroscopy, the X-ray diffraction (XRD) and the 13C NMR studies of the alkali and bleached products confirmed the formation of cellulose type I with high purity and good crystallinity, while scanning electron microscopy (SEM) showed micrometric fibers with lengths reaching 80 µm. Sulfuric acid treatment of these microfibers results in NCC type I or II, depending on the hydrolysis process. SEM of the NCC samples exhibited nanorods with diameter and aspect ratio in the range of 20–40 and 20–25 nm, respectively. Thermogravimetric analysis (TGA) of the MCC and NCC products indicated stable materials with a degradation temperature reaching 240 and 200 °C for MCC and NCC, respectively. The other part of our work concerns the use of the obtained cellulose nanocrystals (type II) for the preparation of reduced graphene oxide composite (NCC/RGO), to demonstrate the reducing properties of the isolated NCCII.

Bacterial infections affect about 1 in 5 patients who receive a dental implant within 5 years of surgery. To avoid the implant rejection it is necessary for the development of innovative biomaterials, with addition or substitution of the ions, for implant coatings that promote a strong bond with the new host bone and antibacterial action. The objective of this work was to synthesize a bioactive glass with different silver concentrations to evaluate their antibacterial performance. The glasses were synthesized with up to 2% silver content by melt-quenching. Structural, morphological, biological, and electrical properties of all samples were studied. The biological behavior was evaluated through cytotoxicity tests and antibacterial activity. The structural analysis shows that the introduction of silver do not promote significant changes, not altering the advantageous properties of the bioglass of the bioglass. It was verified that the glasses with a silver content from 0.5% to 2%, completely prevented the growth of both Staphylococcus aureus and Escherichia coli while being nontoxic toward mammalian cells. Therefore, these bioglasses are promising materials to be used in the production of dental implants with antimicrobial activity.

A simple process of commercial paper functionalisation via in situ polymerisation of conductive polymers onto cellulose fibres was investigated and applied as electrodes in paper-based batteries. The functionalisation involved polypyrrole (PPy) and Poly (3,4-ethylenedioxythiophene) (PEDOT) as conductive polymers with the process of functionalisation optimised for each polymer individually with respect to oxidant-to-monomer ratios and polymerisation times and temperature. Paper with conductivity values of 44 mS/cm was obtained by exposing the samples to pyrrole vapour for a period of 30 min at room temperature; however, polymerisation at temperatures of 40 °C lead to higher conductivity values to up 141 mS/cm. Consequently, functionalised PPy and PEDOT papers were applied as cathodes in batteries with Al foil anodes and commercial paper soaked in an electrolyte solution of NaCl.

Chitosan with three different molecular weights (538 ± 48, 229 ± 45 and 13 ± 3 kDa) was used to develop biodegradable Inverted Colloidal Crystal (ICC) scaffolds with uniform pore size and interconnected pore network. Mass loss and compression modulus were analyzed after hydrolytic degradation in order to understand the influence of molecular weight on structural and mechanical degradation of chitosan ICC structures. Results show that medium molecular weight chitosan (229 ± 45 kDa) retains ICC structure and compression modulus for an extended period (4 weeks) and is therefore the preferred one for the production of ICC for soft tissue engineering.

The use of cellulosic fibers as load bearing constituents in composite materials has increased over the last decade due to their relative cheapness compared to conventional materials such as glass and aramid fibers, their ability to recycle, and because they compete well in terms of strength per weight of material. All-cellulosic based composites prepared from cellulose derivatives based matrices and microcrystalline cellulosic fibers made by direct coupling between fibers and matrix present interesting mechanical and gas permeation properties, thus being potential candidates for packaging materials. Both the cellulosic matrix and the reinforcing fibers are biocompatible and widely used in the pharmaceutical industry, which is very important for the envisaged application. In addition to their biocompatibility, cellulosic systems have the ability to form both thermotropic and lyotropic chiral nematic phases, and the composites produced from the latter show improved mechanical properties due to fiber orientation induced by the anisotropic matrix. The preparation and characterization (morphological, topographical, mechanical, gas barrier properties) of all-cellulosic based composites are described in this chapter.

Electrospun cellulose-based nano and microfibers and a nematic liquid crystal are used to assemble an electro-optical (EO) light-scattering device that shows enhanced characteristics when compared to similar devices. Based on the controlled scattering of light in the composite system, the device can achieve light transmission coefficients tunable from 1% up to around 89%. Simulation of the EO behavior indicates that the roughness of the polymer-liquid crystal interface is crucial for the optical performance of the device.