Synthesis of Urethane Base Composite Materials with Metallic Nanoparticles
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Synthesis of Urethane Base Composite Materials with Metallic Nanoparticles Anayansi Estrada Monje 1, J. Roberto Herrera Reséndiz 2 1 CIATEC, A.C. 201 Omega, Industrial Delta, León, Guanajuato, México, 37545. 2 A. P Resinas, Calle Norte 4 No.3, Nuevo Parque Industrial San Juan del Río, Querétaro, México, 76809 ABSTRACT The antimicrobial properties of polymer materials are used in a verity of applications. Silver nanoparticles are commonly applied to polyurethane foams to obtain antifungal properties. For this study a series of nanocomposites (PU–Ag) from a urethane-type polymer (PU) were reinforced with various amounts of silver nanoparticles having an average size of 20 nm. The surface morphology and antifungal capacity of the nanocomposites were evaluated. As a result, a different surface morphology from PU was found in PU–Ag nanocomposites. The latter nanocomposite showed enhanced thermal and mechanical properties, when compared with the PU without silver nanoaprticles. The nanocomposite also exhibited good antifungal properties that can be used in a variety of applications. INTRODUCTION Polyurethane (PU) polymer is commonly used in a variety biomedical application due to its biocompatibility, easy processing and positive physical-mechanical properties [1-3]. PU is comprised of rigid and soft segments enabling its final properties to be manipulated by altering the ratio or chemistry of the batch components. [4]. The term nanonomposite is used to describe polymeric systems that contain nanometric reinforcements, with an average particle size less than 100 nm, dispersed into a polymer matrix [5, 6]. These nanomaterials have gained interest in the recent years due to their unique properties [7]. Presently, the synthesis of reinforced polymer with metallic nanoparticles has fostered innovative ways of engineering materials that exhibit better electrical, optical, mechanical, antifungal and antibacterial properties. The antifungal properties have been familiar to scientists for decades [8], with silver derivatives like sulfadiazines used to prevent bacteria growth in potable water bottles [9, 10]. For example, silver derivatives have been applied in a polypropylene matrix for sanitary applications such as surgical masks, filters, diapers, etc. [11]. Although the antibacterial effect of silver on microorganisms is well known, the mechanism by which this effect is achieved is only partially understood. Scientists have hypothesized that silver strongly interacts with thiol groups of particular enzymes, by inactivating the enzyme and inhibiting vital processes within the microorganisms [11, 12]. Other studies have demonstrated structural changes in the cellular membrane, as well as, the formation of small electron-dense granules when combined with silver and sulfur. An alternative mechanism involves the absorption and accumulation of silver ions (Ag+) in the bacterial cells causing shrinkage of the cytoplasm or the detachment of the cellular wall; as a result, the DNA condenses and loses it replication ability. In addition
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