Aggregation of colloidal nanoparticles in polymer matrices

Abstract

Colloidal nanoparticles may possess many functional properties, whose nature may be electronic, chemical, biological, mechanical, etc. It is often advantageous to incorporate them into a matrix material, e.g. a polymer solution or melt, or an elastomer, in order to obtain a 'nanomaterial' with additional properties brought in by the filler particles. One of the basic but nonetheless crucial properties is the mechanical strength of such polymer nanocomposites, whose rheological (or mechanical) properties are usually better than those of the pure matrix.The precise origin of this mechanical reinforcement effect, however, remains unclear.In this context, some recent studies of the structure and mechanical properties of a special type of nanocomposites are reviewed here. In silica-latex systems, a latex film with silica inclusions is formed from a colloidal solution of both components. During drying of the solution, the formation of silica domains can be controlled via the physico-chemical properties of the solution. Well-defined silica aggregates embedded in a polymer matrix can be generated, and the mechanical properties of the resulting nanocomposite have been shown to be directly correlated to the average structure. We believe that the fine-tuning of the structure of the filler phase opens new perspectives for systematic studies of the reinforcement effect, e.g. by modifying filler-polymer interfacial properties at fixed structure, or by generating original structures. Figures: 10

Ultrafast on-site selective visual detection of TNT at sub-ppt level using fluorescent gold cluster incorporated single nanofiber

“…The most challenging step is the homogeneous distribution of clusters in NFs with the preservation of their optical properties. 5,6 Precise optimization and many efforts have led to the accomplishment of this goal. Additionally, the utmost consequence of this assembly is its high stability, permitting better storage and instantaneous use.…”

Structure of interacting aggregates of silicananoparticles in a polymer matrix: small-angle scattering and reverse Monte Carlo simulations

“…The resulting nanocomposite has been shown to have very interesting mechanical properties even at low filler volume fraction. The reinforcement factor, e.g., which is expressed as the ratio of Youngs modulus of the composite and the one of its matrix, E/E latex , can be varied by a factor of several tens at constant volume fraction of silica (typically from 3 to 15%) [28,29]. In this context it is important to recognize that the silica-polymer interface is practically unchanged from one sample to the other, in the sense that there are no ligands or grafted chains connecting the silica to the matrix.…”

Mean-field models of structure and dispersion of polymer-nanoparticle mixtures

“…11 In this article, we specifically focus on an issue which has commanded significant attention in PNCs, viz., dispersion control of nanoparticles in polymer matrices. Most combinations of polymers and pristine nanofillers tend to be immiscible, with the fillers undergoing aggregation either due to strong Van der Waals interactions between themselves or due to polymer-mediated interparticle attractions 5,6,3,9,[24][25][26] (an example illustrating the dispersion issue is displayed in Fig. 1 …”