Dispersion nanocomposites

Keywords nanocomposites, dispersion, aspect ratio, in-situ, melt, morphology, tensile properties, glass transition temperature, degradation, functionalization, electrical conductivity, resistivity. 

Chou CS, Lafleur EE, Lorah DP, Slone RV, Neglia KD (2005) Aqueous nanocomposite dispersions processes, compositions and uses thereof. US Patent 6,838,507... 

In order to further prove the above speculation, the TEM images of the PPy/T-CN nanocomposites dispersed in ethanol were given in Fig. 13.14. The morphologies of the composites became smaller with the increasing T-CNs. The width of the T-CNs was about 20 nm, while that of the composites was 30-50 nm. A thickness layer of PPy about 30 nm was deposited on the T-CNs. We could find that on the surface of the nanocomposites absorbed a lot of uniform spherical nanoparticles and their diameters are about 2.5 nm. According to the previous work, they might be PPy nanoparticles [43]. And we could also find on the surface of the covered layer adhered a lot of spherical nanoparticles ranging from about 20 to 100 nm, which is consistent with the SEM results. This indicated that the T-CNs molecules acted as the templates as well as the... 

A Facile Route to Organic Nanocomposite Dispersions of Polyaniline - single Wall Carbon Nanotubes... 

Despite of the advances in preparations, the processing of such nanocomposites still remains a challenge due to intractability of both PANI as well as SWNT. Up until now there is no simple route to process such nanocomposite that will facilitate the use in electronic devices. Here, we used anionic surfactant as a common stabiliser for polyaniline as well as for SWNT. Based on this work, we report a facile route to obtain organic nanocomposite dispersions of polyaniline with variable concentrations of (up to 10 wt%) SWNT. From the processing point of view, this route eliminates the need for polyaniline to be de-doped followed by dissolution in suitable solvent and re-doping to regain the conductivity. 

Scheme - 4 Organic Nanocomposite Dispersions of PANI-SWNT... 

Organic nanocomposite dispersions of PANI-SWNT are prepared by in situ synthesis of polyaniline as shown in Scheme - 3. Ammonium persulfate is added to aqueous phase and aniline in xylene is added from the top. After rigorous stirring, the system is then left idle, during which phase inversion occurs. No traces of SWNT were observed in the aqueous phase. The nanocomposite dispersion is then taken from the top and washed with excess amount of xylene. The filtered material is then dried imder dynamic vacuum at 60 °C for more than 24 hours. 

This result confirms the role of surfactant as an additional dopant to PANI. In presence of 2% SWNT, the conductivity of the nanocomposite dispersions containing NaDBS is much higher (11.08 S/cm) compared to its SDS counterpart 8.01 S/cm. It is known from the literature that both NaDBS and SDS show strong interactions with SWNT and self organisation on SWNT surface [10, 24]. However, from FT-IR and UV-spectroscopy, it can be suggested that combination of SWNT-SDS stimulate more restrictions on chain conformations of PANI as compared to NaDBS counterpart. As a result, higher conductivity is observed in nanocomposites prepared using NaDBS. 

Khare, H. S. and Bmris, D. L. 2010. A quantitative method for measuring nanocomposite dispersion. Polymer 51 719-729. 

Silica nanoparticles could also be encapsulated with an epoxy resin to produce water-borne nanocomposite dispersions by using the phase-inversion emulsification technique [98]. Microscopy results indicated that all the siHca nanoparticles were encapsulated within the composites and uniformly dispersed therein. 

During the past few years, nanoparticles have been incorporated into the polymer matrix to develop a polymer nanocomposite. Although processing techniques of the nanocomposite are inherently different, all of them have to address the following issues that will directly affect the properties of the nanocomposite dispersion, alignment and functionalization. Common processing techniques of polymer nanocomposites include ... 

Stable, aqueous nanocomposite dispersions containing cellulose whiskers and a poly(styrene-co-hexyl-acrylate) matrix were prepared via miniemulsion polymerization. 

Nanocellulose-reinforced acrylate latex can also be an interesting material for the surface coating industry. Mabrouk et al. [57] used an one-step miniemulsion polymerization method to prepare stable aqueous nanocomposite dispersions based on cellulose whiskers extracted from the rachis of the date palm tree and a poly (styrene-co-2-ethyl hexylacrylate) copolymer. A reactive silane, i.e., methacryloxypropyl triethoxysilane (MPS) was added to stabiHze the dispersion and favor the anchoring of the whiskers on the polymer particles. The particle size of the polymer dispersion ranged between 90 and 160 nm for a whisker content varying from 1 to 5 wt%. 

Polymer blends, nanocomposites, dispersion, clay, carbon nanotubes, nanoparticles, solid-state shear pulverization. 

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