The major problem in designing cellulose based-biocomposites is the lack of misci­bility between components, that is, hydrophilic biopolymers from wood fibers and hydrophobic substances (matrix), leading to poor adhesion between matrix and fiber in the final composite. To overcome this problem, chemical coupling agents have been employed to improve the adhesion between fibers and matrix through a variety of approaches that include chemical linking, secondary forces, self-assembly, en­tanglement, and mechanical interblocking.41 Chemical treatments, therefore, should be considered for improving any type of chemistry for the bonding/adhesion. For example, a number of compounds can promote adhesion such as sodium hydroxide, silane, acetic acid, acrylic acid, isocyanates, potassium permanganate, peroxide, etc. Later, chemical coupling agents such as amphiphilic polymers could be used in small quantities to allow the substrates of interest to bond.15

Cellulose based-nanocomposites (whiskers and nanofibrillated cellulose) will be explored in this section because they have been extensively investigated as re­inforcing materials in recent years. Whiskers, nanocrystalline cellulose, cellulose nanoparticles, etc., all refer to the isolated crystalline regions of cellulose that pos­sess on of the highest material mechanical strengths known. They are highly ordered and contribute greatly to reinforcing materials because of their high surface area and excellent mechanical properties.42

Yet, a critical parameter to good final material properties for the whiskers is that they should be well separated and homogeneously distributed in the matrix. Unfortunately, cellulose whiskers possess a very high surface energy and thus can­not be dispersed well in nonpolar media such as organic solvents or related media; their incorporation as a reinforcement filler for nanocomposites or in complex fluids has up until now be limited to aqueous or polar environments. Their flocculation or aggregation in nonpolar solvents (alkanes, olefins, etc.) can only be avoided by two routes, viz., application of surfactants onto the whiskers (formation of pseudomi­celles) or graft-onto or -from the whisker surface using the appropriate polymeriza­tion technique.42