Incorporation of nano metal particles with paper matrices
The upraising value of nano metal particles is increasing from one day to another due to its wide usage in enormous range of applications in several fields. This high value is due to the new approaches of the nano metal science which enabled the researchers to improve the characteristics of these nano metal particles through some processes of incorporation of nano metal particles on the different cellulosic fibers substrates. One of these substrates is the paper fibers which is a natural polymer. Nano metal particles retention may occur in case of incorporation of the nano metal particles in the paper fibers substrate. The adherence to the paper fibers matrices via weak interactions like Van der Waals force would lead to weak retention. Raising the retention may take place through incorporating nano metal particles in paper matrices by adding suitable linkers, binders, or retention aids. While these substances improve the retention and the strength properties of paper sheets, however they add extra cost to the final product. Also addition of these retention aids and linkers restrict the active sites availability in the nano metal particles, which in turn decreases the applicability of these nano metal particles in some applications. More modern hydrothermal method was used to incorporate nano metal particles in paper matrices in a single step without adding any binders, linkers or retention aids (in situ) The purpose of this state of art is to present and discuss; the main synthesis methods of nano metal particles, principal characteristics and different attachment methods of nano metal particles. Correspondence to: Abeer M. Adel, National Research Center, Cellulose and Paper Department, 33 El Bohouth St. (Former El Tahrir St. Dokki, Giza, Egypt. E mail: abeermadel2003@yahoo.com Received: September 17, 2016; Accepted: October 17, 2016; Published: October 20, 2016 Figure 1. Photo induced redox reaction of TiO2. Adel AM (2016) Incorporation of nano metal particles with paper matrices Volume 1(2) 36 46 Interdiscip J Chem, 2016 doi: 10.15761/IJC.1000107 metal particles can be obtained by incorporating them on various substrates such as ceramics, glass, polymers, cellulose fibers, and paper, however, each substrate has its own advantage and disadvantage [8,9] Paper matrices can be considered as superior alternative to other substrates since it is biodegradable, biocompatible, cost effect and renewable [10] Also, due to the porous structure and hydrophilicity of fiber surface, paper matrices can absorb suspension of nano metal particles via capillary forces leading to higher loading of nano metal particles. Moreover, small volume of nano metal particles deposited on paper sheets can be used in different devices which gives optical [11] antimicrobial [12] anti counterfeiting [13] surface enhanced raman scattering [14] and surface plasmon resonance [15] However, paper has some disadvantages such as low strength properties and deteriorates of mechanical properties under moist environments. The aim of this state of art is to present and discuss; the main synthesis methods of nano metal particles, principal characteristics and different attachment methods of nano metal particles. Synthesis of nano metal particles Nano metal particles can be synthesized by three main approaches; the physical approach which utilizes several methods such as; evaporation/condensation and laser ablation. The chemical approach, where metal ions solution is reduced in conditions that motivating the consequent formation of small metal clusters or aggregates. Finally, the combination of inorganic nano metal particles and biological structures is also a favorable technique where no toxic chemicals are used [16] Chemical methods can be classified in terms of the nature of the reducing agents to classical chemical, using the famous chemical reducing materials e.g. hydrazine, sodium borohydride, hydrogen, etc. and radiation chemical where solvated electrons generated by the ionizing radiation starts the reduction process [17] Moreover, chemical methods can be classified in terms of using non deleterious solvent and naturally occurring reducing agent e.g. polysaccharides or plants extract or biological micro organism e.g. bacteria and fungus as reductions materials [18] Stabilization of nano metal is always discussed in terms of electrostatic and steric stabilization. Electrostatic stabilization is the coordination of anionic species, e.g. halides, carboxylates or polyoxoanions, to metal particles which leads to the formation of an electrical double layer. This double layer results in columbic repulsion force between the nano metal particles. On the other hand, steric stabilization may occur due to the presence of bulky, typically organic materials that, due to their bulk, hinder the nanoparticles from diffusing together. Polymers and large cations like alkylammonium are examples of steric stabilizers [19]