Nanocomposites of poly(methyl methacrylate)/reduced graphene oxide (PMMA/rGO) without and with decorated magnetite nanoparticles with a segregated structure were prepared using emulsifier-free emulsion polymerization. Various characterization techniques were employed to validate the presence of the nanofillers and the formation of the segregated structure within the nanocomposites. The percolation threshold of the nanocomposites was found to be 0.3 vol %, while a maximum electrical conductivity of 91.2 S·m and electromagnetic interference shielding effectiveness (EMI SE) of 63.2 dB (2.9 mm thickness) were achieved for the PMMA/rGO nanocomposites at a loading of 2.6 vol % rGO. It was also observed that decorating rGO with magnetite nanoparticles (hybrid nanocomposites) led to a tremendous increase in EMI SE. For instance, 1.1 vol % PMMA/rGO nanocomposites indicated an EMI SE of 20.7 dB, while adding 0.5 vol % magnetite nanoparticles enhanced EMI SE to 29.3 dB. The excellent electrical properties obtained for these nanocomposites were ascribed to both superiorities of the segregated conductive structure and magnetic properties of the magnetite nanoparticles.
Silver nanowires (AgNWs) were synthesized by AC electrodeposition of Ag into porous aluminum oxide templates. AgNWs were embedded into polystyrene via a solution processing technique to create a nanocomposite. For comparison, carbon nanotube (CNT)/polystyrene nanocomposites were identically generated. TEM and XRD analyses confirmed the synthesis of AgNWs with an average diameter and length of 25 nm and 3.2 mm, respectively. TEM images also revealed that at the molding temperature (240 C) AgNWs transformed into a chain of nanospheres. At low filler loadings, the AgNW/polystyrene nanocomposites presented inferior electrical properties compared to the CNT/polystyrene nanocomposites. This was attributed to a lower aspect ratio, fragmentation phenomenon and poorer conductive network for AgNWs. However, at high filler loadings, the electrical properties of the AgNW/polystyrene nanocomposites significantly increased. It seems that at high filler loadings, the conductive network was well-established for both types of nanocomposites and thus, the higher innate conductivity of AgNWs played a dominant role in presenting superior electrical properties. Fig. 5 EMI SE (overall, reflection and absorption) of AgNW/PS and MWCNT/PS nanocomposites as a function of nanofiller loading.Fig. 6 (a) Imaginary permittivity, and (b) real permittivity as a function of nanofiller loading. 56596 | RSC Adv., 2015, 5, 56590-56598 This journal is
Nanocomposites were prepared by adding 1-3 vol % multiwalled carbon nanotubes (MWCNTs) to polyamide 6 (PA6), polypropylene (PP), and their co-continuous blends of 60/40 and 50/50 volume compositions. Because of the good interaction and interfacial adhesion to the PA6, nanotubes were disentangled and distributed evenly through nanocomposites containing PA6. In contrast, lack of active interactions between the matrix and the CNTs resulted in poor tube dispersion in PP. These observations were then verified by studying the rheology and electrical conductivity of their respective nanocomposites. Absence of percolated CNT clusters and possible wrapping of the tubes by PA6 resulted in low electrical conductivity of PA6/CNT nanocomposites. On the other hand, despite the weak dispersion of the tubes, electrical conductiv-ities of PP/CNT nanocomposites were much higher than all other counterparts. This could be the result of good threedimensional distribution of the agglomerated bundles and secondary aggregation of tubes in PP. Adding CNTs to blends of PA6/PP (60/40 and 50/50) resulted in almost full localization of carbon nanotubes in PA6, leading to their higher effective concentration. At the same CNT loadings, the blend nanocomposites had three to seven orders of magnitude higher electrical conductivity than pure PA6.
FRAP (fluorescence recovery after
photo bleaching) is a method
for determining diffusion in material science. In industrial applications
such as medications, foods, Medtech, hygiene, and textiles, the diffusion
process has a substantial influence on the overall qualities of goods.
All these complex and heterogeneous systems have diffusion-based processes
at the local level. FRAP is a fluorescence-based approach for detecting
diffusion; in this method, a high-intensity laser is made for a brief
period and then applied to the samples, bleaching the fluorescent
chemical inside the region, which is subsequently filled up by natural
diffusion. This brief Review will focus on the existing research on
employing FRAP to measure colloidal system heterogeneity and explore
diffusion into complicated structures. This description of FRAP will
be followed by a discussion of how FRAP is intended to be used in
colloidal science. When constructing the current Review, the most
recent publications were reviewed for this assessment. Because of
the large number of FRAP articles in colloidal research, there is
currently a dearth of knowledge regarding the growth of FRAP’s
significance to colloidal science. Colloids make up only 2% of FRAP
papers, according to ISI Web of Knowledge.
By using an independent self-assembly process that is
occasionally
controlled by evaporation, cellulose nanocrystals (CNCs) may create
films (pure or in conjunction with other materials) that have iridescent
structural colors. The self-forming chiral nematic structures and
environmental safety of a new class of photonic liquid crystals (LCs),
referred to as CNCs and CNC-embedded materials, make them simple to
make and treat. The structure of the matrix interacts with light to
give structural coloring, as opposed to other dye pigments, which
interact with light by adsorption and reflection. Understanding how
CNC self-assembly constructs structures is vital in several fields,
including physics, science, and engineering. To constructure this
review, the colloidal characteristics of CNC particles and their behavior
during the formation of liquid crystals and gelling were studied.
Then, some of the recognized applications for these naturally occurring
nanoparticles were summarized. Different factors were considered,
including the CNC aspect ratio, surface chemistry, concentration,
the amount of time needed to produce an anisotropic phase, and the
addition of additional substances to the suspension medium. The effects
of alignment and the drying process conditions on structural changes
are also covered. The focus of this study however is on the optical
properties of the films as well as the impact of the aforementioned
factors on the final transparency, iridescent colors, and versus the
overall response of these bioinspired photonic materials. Control
of the examined factors was found to be necessary to produce reliable
materials for optoelectronics, intelligent inks and papers, transparent
flexible support for electronics, and decorative coatings and films.
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