Structure, Magnetic and Ion-Exchange Properties of Self-Assembled Triaza-Copper(II)-Oxalate Hybrides Having Nanoscale One-Dimensional Channel

Abstract

There are numerous examples where animals or plants synthesize extracellular high-performance skeletal biocomposites consisting of a matrix reinforced by fibrous biopolymers. Cellulose and chitin are classical examples of these reinforcing elements, which occur as whisker-like microfibrils that are biosynthesized and deposited in a continuous fashion. In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. Starch is another example of natural semicrystalline polymer that is produced by many plants and occurs as microscopic granules. It acts as a storage polymer in cereals and tubers. These abundant and natural polymers can be used to create high performance nanocomposites presenting outstanding properties. Aqueous suspensions of crystallites can be prepared by acid hydrolysis of the purified substrates. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. For cellulose and chitin, these monocrystals appear as rod-like nanoparticles which dimensions depend on the biological source of the substrate. In the case of starch they consist of platelet-like nanoparticles. High reinforcing capability was reported resulting from the intrinsic chemical nature of these polymers and from their hierarchical structure. During the last decade, many works have been devoted to mimic biocomposites by blending cellulose whiskers from different sources with polymer matrices.

Crystalline Nanocellulose — Preparation, Modification, and Properties

“…By using a 64 wt% sulphuric acid solution, 0.5-2% sulfate groups will be attached to the surface of the nanocrystal [31]. Due to the charged sulfate groups, CNC will form stable colloidal dispersion when diluted in water to specific concentrations [32][33][34][35].…”

“…Most of the literature that describes chemical modification of nanoparticles had the aim of improving the interfacial compatibility between the nanocrystals and various polymer matrices. A better compatibility could enhance the mechanical properties of the composite materials and addition of just a few percent of nanocellulose to a polymer matrix could improve the mechanical properties of the significant composite material [27,35,62,90]. Most of the literature about chemical modification on nanocellulose describes a surface modification of the crystals or fibrils.…”

Grinding process for the production of nanofibrillated cellulose based on unbleached and bleached bamboo organosolv pulp

“…Although the bleaching removes the amorphous components of the fiber such as hemicellulose and lignin, the amorphous part of the cellulose remains in the fiber, which is removed only by acid hydrolysis, enzymatic, or bacterial processes. Therefore, the pulp after bleaching consists of amorphous cellulose (less ordered) and crystalline cellulose (more ordered) (Pääkko et al 2007;Dufresne 2006;Klemm et al 2005;Beck-Candanedo et al 2005).…”

Crystal structure and photoluminescence properties of a new monomeric copper(II) complex: bis(3-{[(3-hydroxypropyl)imino]methyl}-4-nitrophenolato-κ3 O,N,O′)copper(II)

“…In this context, Schiff base ligands have been used as fluorescent sensors for the detection of certain metal ions (Zhou et al, 2010). Cu II -Schiff base complexes have also attracted extensive interest due to their structural, electronic, magnetic and luminescence properties (Yahsi, 2016;Yashi et al, 2016;Chang et al, 2006;Keypour et al, 2016;Safaei et al, 2011;Hopa & Cokay, 2016a;Erkarslan et al, 2016;Naskar et al, 2010;Obali & Ucan, 2015).…”