Mechanism of Particle Formation in Silver/Epoxy Nanocomposites Obtained through a Visible-Light-Assisted in Situ Synthesis

Abstract

A detailed understanding of the processes taking place during the in situ synthesis of metal/polymer nanocomposites is crucial to manipulate the shape and size of nanoparticles (NPs) with a high level of control. In this paper, we report an in-depth time-resolved analysis of the particle formation process in silver/epoxy nanocomposites obtained through a visible-light-assisted in situ synthesis. The selected epoxy monomer was based on diglycidyl ether of bisphenol A, which undergoes relatively slow cationic ring-opening polymerization. This feature allowed us to access a full description of the formation process of silver NPs before this was arrested by the curing of the epoxy matrix. In situ time-resolved small-angle X-ray scattering investigation was carried out to follow the evolution of the number and size of the silver NPs as a function of irradiation time, whereas rheological experiments combined with near-infrared and ultraviolet-visible spectroscopies were performed to interpret how changes in the rheological properties of the matrix affect the nucleation and growth of particles. The analysis of the obtained results allowed us to propose consistent mechanisms for the formation of metal/polymer nanocomposites obtained by light-assisted one-pot synthesis. Finally, the effect of a thermal postcuring treatment of the epoxy matrix on the particle size in the nanocomposite was investigated.

Structure and Bottom-up Formation Mechanism of Multisheet Silica-Based Nanoparticles Formed in an Epoxy Matrix through an In Situ Process

“… 3 , 20 This is of great interest and was recently actively explored also in the case of non silicatic fillers. 21 , 22 When dealing with sol–gel chemistry, if the reaction rates are comparable, an interpenetrating network may also be obtained from the simultaneous reactions of the organic monomer and the sol–gel precursor. 20 In addition, the sol–gel route offers the formation of an inorganic phase starting from simple low-molecular-weight precursors, allowing a nanolevel molecular design of the final structure.…”

“…Very often, unprecedented materials were produced whose properties are not simply a combination of the two components alone . A common way to develop these materials is the use of the sol–gel synthesis route. − The mild synthesis conditions in the sol–gel process allow generating an inorganic phase in the presence of the monomer or the polymer through the so-called “ in situ ” process, in which both phases are formed successively in one procedure. , This is of great interest and was recently actively explored also in the case of non silicatic fillers. , When dealing with sol–gel chemistry, if the reaction rates are comparable, an interpenetrating network may also be obtained from the simultaneous reactions of the organic monomer and the sol–gel precursor . In addition, the sol–gel route offers the formation of an inorganic phase starting from simple low-molecular-weight precursors, allowing a nanolevel molecular design of the final structure.…”

Recent Progress in Antimicrobial Strategies for Resin-Based Restoratives

“…Moreover, silver nanoparticles are easy to clump into agglomerates due to their ultrafine size, and silver salts are difficult to dissolve in hydrophobic dental resin monomers, which are challenges faced in AgNP applications [ 40 ]. In situ synthesis methods can avoid agglomeration formation during the procedure of mixing AgNPs into resin [ 41 ]. Ren et al showed that AgNPs were successfully synthesized in the resin matrix by reducing silver ions in situ through photoinitiation and proved to have good antibacterial effects [ 42 ].…”

Effect of Light Intensity on the Aggregation Behavior of Primary Particles during In Situ Photochemical Synthesis of Gold/Polymer Nanocomposites

“…Furthermore, by varying the solar flux, the authors were able to control the NP size distribution and, therefore, the final plasmonic response of the nanocomposite. Alternatively, metal/polymer nanocomposites can be obtained through a simultaneous reduction–polymerization approach. − Yagci et al demonstrated that UV-generated free radicals can initiate the polymerization of an acrylic resin, and at the same time, they can reduce a Au­(III) precursor to Au(0) . In this way, gold particle formation and matrix polymerization occur simultaneously in a one-pot process.…”