Polymer-Silver Nanocomposites

Infections caused by antibiotic-resistant bacteria expose an important risk to human health around the world. These bacteria are very resistant to traditional antibiotics owing to acquired resistance, inadequate diffusion and intracellular inactivation. Therefore, the development of novel antimicrobial materials with high protection and antibacterial activity, which lack bacterial resistance, is critical. 

An ion exchange resin bead, which has fungal and bacterial growth on it after use in a traditional domestic tap water treatment filter, is typically used for the elimination of undesired metal ions (ions causing water hardness, iron, heavy metals and so on). The stabilisation and immobilisation of silver NP in such matrices is therefore a promising method as two complementary water treatment processes could be achieved with a single material, while at the same time improving the safety of the nanocomposites [13]. 

The surface alteration of ion exchange materials used in conventional water treatment has been carried out. The difference in cell viability over time of Escherichia coli suspensions in contact with a membrane nanocomposite (containing silver NP) or 

Rhodanine by-products have been used as antiviral, antibacterial, antihistaminic and anticorrosion agents [34, 35]. Additionally, they have also been used to identify metal ions as the rhodanine molecule has metal-binding functional groups, such as thioamide and amide [36, 37]. It is thought that the improved antimicrobial efficacy of the silver/polyrhodanine nanofibres is due to the joint antimicrobial activity of silver and polyrhodanine nanofibres. Silver NP-embedded polyrhodanine nanofibres can be prepared via chemical oxidation polymerisation. 

In order to imnimise the risk of increasing antibiotic resistance associated with the use of antimicrobial devices, transition-metal-containing polyurethanes (PU) have been loaded with ciprofloxacin, which was chosen because it possesses a different mechanism of action [43]. In this way, the presence of two antibacterial agents in the polymer allows the development of an antimicrobial polymer whose activity is not limited by the increasing occurrence of antibiotic resistance. 

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The complex formed of silver ions and acrylonitrile monomers provides an excellent precursor for the synthesis of polymer/ silver nanocomposite [Wen-Fu and Kai-Tai, 2010 Carotenuto et al., 2005]. When this solution is irradiated with UV, the acrylonitrile polymerized simultaneously Ag gel reduced Ag° [Zhongping et al., 2001]. 

Hariprasad, E., Radhakrishnan, T.P., 2013. In situ fabricated polymer—silver nanocomposite thin film as an inexpensive and efficient substrate for surface-enhanced Raman scattering. Langmuir 29, 13050-13057. 

PP/silver nanocomposite fibres were prepared with the aim of achieving permanent antibacterial activity in a common synthetic textile. The fibres were melt-spun by coextmsion of PP and PP/silver masteibatches using general conjugate spinning. Masteibatches were made up of a mixture of PP chips and nano-sized silver powder. The antibacterial efficacy of spun fibres was high when the masteibatch was used as the sheath rather than the core. The antibacterial activity of nano-silver in fibres was evaluated after a certain contact time and calculated by percent reduction of two types of bacteria. Staphylococcus aureus and Klebsiela pneumoniae. DSC and wide-angle X-ray diffraction were used for analysis of stractuie, thermal properties and crystallisation behaviour of the spun fibres. SEM was carried out in order to observe particle distribution on the nanocomposite fibres. 17 refs. (2nd International Conference on Polymer Fibres, Manchester, UK, July 2002)... 

In in-situ polymerization, nanoscale particles are dispersed in the monomer or monomer solution, and the resulting mixture is polymerized by standard polymerization methods. This method provides the opportunity to graft the polymer onto the particle surface. Many different types of nanocomposites have been processed by in-situ polymerization. Some examples for in-situ polymerization are polypyrrole nanoparticle/amphiphilic elastomer composites magnetite coated multi-walled carbon nanotube/polypyrrole nanocomposites and polypyrrole/ silver nanocomposites. The key to in-situ polymerization is appropriate dispersion of the filler in the monomer. This often requires modification of the particle surface because, although dispersion is easier in a liquid than in a viscous melt, the settling process is also more rapid. 

Sunflower oil-based hyperbranched and linear thermoplastic polyure-thane/silver nanocomposites have also been prepared by the in situ catalytic reduction of silver salt, using a catalytic amount of organic tin compound. The virgin polymer and its nanocomposites are entirely thermoplastic as... 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

Pourabas and Peyghambardoost [53] showed that copper filled epoxy resin composite had electrical conductivity properties. Afzal and co-workers [104] studied the electrical properties of PANI/silver nanocomposites. The silver nanoparticles in PANI reduced the charge trapping centres and increased the conducting channels of the polymer. 

Mtimet I, Lecamp L, Kebir N, Burel F, Jouenne T. Green synthesis process of a polyurethane-silver nanocomposite having biocide surfaces. Polym J 2012 44 1230-7. 

Chalal Sarnia, Haddadine Nabila, Bouslah Naima, and Benaboura Ahmed. Preparation of poly (acrylic acid)/silver nanocomposite by simultaneous polymerization-reduction approach for antimicrobial application. J. Polym. Res. 19 no. 12 (2012) 1-8. 

Lee A, Lichtenhan JD (1999) Thermal and viscoelastic property of epoxy-clay and hybrid inorganic-organic nanocomposites. J Appl Polym Sci 73 1993-2001 Lee H, Neville K (1967) Handbook of Epoxy Resins. McGraw-Hill, New York Li SM, Jia N, Ma MG, Zhang Z, Liu QH, Sun RC (2011a) Cellulose-silver nanocomposites microwave-assisted synthesis, characterization, their thermal stability, and antimicrobial property. Carbohydr Polym 86 441 147... 

Sawada, H., Sasaki, A., Sasazawa, K Toriba, K., Kakehi, H Miura, M. et al. (2008) Preparation of colloidal stable fluoroalkyl endsilver nanocomposites - application to the siuface modification of traditional organic polymers with these nanocomposites. Polymers for Advanced Technologies, 19, 419-424. 

Rulis AM, Levitt JA (2009) FDA s food ingredient approval process, safety assurance based on sdentilic assessment. Regul Toxicol Pharmacol 53(1) 20-31 Sanchez-Valdes S, Ortega-Ortiz H, Ramos-de Valle LF et al (2009) Mechanical and antimicrobial jHoperties of multilayer films with a polyethylene/silver nanocomposite layer. J Appl Polym Sci lll(2) 953-962... 

Murray CB, Kagan CR, Bawendi MG (2000) Synthesis and characterizati(Hi of mrmodisperse nanocrystals and close-packed nanocrystal assemblies. Ann Rev Mater Res 30(1) 545-610 Nikonorova NA, Barmatov EB, Pebalk DA, Barmatova MV, Dommguez-Espinosa G, Diaz-Calleja R, Pissis P (2007) Electrical properties of nanocomposites based on comb-shaped nematic polymer and silver nanoparticles. J Phys Chem C 111(24) 8451-8458 Okamoto M (2004) Encyclopedia of nanoscience and nanotechnology. In Nalwa HS (ed) Polymer/clay nanocomposites, vol 8. American Scientific, Stevenson Ranch, pp 791-843 Osipov MA, Gorkunov MV (2014) Molecular theory of phase separation in nematic liquid crystals doped with spherical nanoparticles. ChemPhysChem 15(7) 1496-1501... 

In this part of the chapter we discuss (a) the controlled thermolysis of thiolate solutions in polystyrene matrix at temperatures above the polymer glass transition temperature and (b) the reaction mechanism in the case of silver-polystyrene nanocomposite systems. However, the same reaction mechanism is probably involved in the thermolysis of other mercaptide-polystyrene systems. This technique has proven to be an excellent new preparative scheme for the generation of both metal and sulfide clusters in polymers. In particular, high-molecular-weight n-alkanethiolates have shown to be the most effective compound class since the low volatility of thermolysis by-products avoids film foaming during the annealing process. 

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