Nanostructures blends

Foaming of nanostructured blends - so far, only the use of low contents of block copolymers (up to 2 wt%) as nucleating agents was discussed [19]... 

Descriptive Foam Model of the Microstructured and Nanostructured Blend Systems... 

Chin Han Chan, PhD, is an associate professor at the Faculty of Applied Sciences, Universiti Teknologi MARA [MARA University of Technology) in Selangor, Malaysia. She has received many research grants, has published many articles in professional journals, has published chapters in books, and has presented at many professional conferences. Her field of interest includes epoxidized natural rubber-based nanostructured blends, thermoplastic elastomer, biodegradable polyester/polyether blends, and solid polymer electrolytes. 

Figure 9.31 Possible schemes of the heterogeneous nucleation foaming mechanism and pore growth in poly(methyl methacrylate) (PMMA)/MAM nanostructured blends.

Poly (thiophene)s are of particular interest as electfochromic materials owing to their chemical stability, ease of synthesis and processability. For the most part, current research has been focused on composites, blends and copolymer formations of several conjugated polyheterocyclics, polythiophene and its derivatives, especially PEIX)T. In one example, poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(2-acrylamido-2-methyl-l-propanesulfonate) (PAMPS) composite films were prepared by Sonmez et al. for alternative electrochromic applications [50]. Thin composite films comprised of PEDOT/PAMPS were reported to switch rapidly between oxidized and neufial states, in less than 0.4 s, with an initial optical contrast of 76% at A.max. 615 nm. Nanostructured blends of electrochromic polymers such as polypyrrole and poly(3,4-ethylenedioxythiophene) were developed via self-assembly by Inganas etal. for application as an electrochromic window [26]. Uniir etal. developed a graft-type electrochromic copolymer of polythiophene and polytetrahydrofuran for use in elecfiochromic devices [51]. Two EDOT-based copolymers, poly[(3,4-ethylenedioxythiophene)-aZ/-(2,5-dioctyloxyphenylene)] and poly[(3,4-ethylenedioxythiophene)-aft-(9,9 -dioctylfluorene)] were developed by Aubert et al. as other candidates for electrochromic device development [52],... 

In this chapter the different ways of fabrication of thermoplastic-thermoset nanostructured blends, where thermoplastic is the matrix, will be discussed. The issues of phase separation and morphology shall be treated together with the properties of the blends and conclusions will be drawn. 

The preparation of nanosttuctured polymer blends for immiscible polymers, with a phase size of less than lOOnm, is very challenging using normal processing methods currently available. Typically, blends of this type are prepared by one of three methods solution casting, melt extrusion, or reactive blending [7]. Very recently, nanostructured blends have been produced from block copolymers by using conventional melt processing [64],... 

Some examples of high barrier polymers and their nanostructured blends are discussed in this section. 

The dielectric properties of nanostructured polymer blends comprise a low dielectric constant compared with pristine polymer. Such results could be ascribed to the increase in the free volume reduction in chain-chain interaction in nanostructured polymer blends [64,65]. It was observed that the polyamides containing bulky POSS and fluoro groups could effectively decrease the dielectric constants of the polyamides. The detreasing trend of dielectric constant in polyamide nanostructured polymer blends indicates that changing the substitute reduces the dipole-dipole interaction in the nanostructured blends. The introduction of nanoparticles into polyamide reduces its polarizability aud increases the free volume in the resulting hybrid nanostructured blends. Moreover, the polyamides with bulky POSS groups increase the free volume of polyamide and further lower dielectric constant values. This may... 

Pandit R, Berkessel A, Lach R, Grellmann W, Adhikari R. Synthesis and characterization of nanostructured blends of epoxy resin and block copolymers. Nepal J Sci Technol 2012 13(l) 81-8. 

Sol-gel method is the most welcome route for the preparation of inorganic coatings. The method is simple, inexpensive, easy to control, and uses a low-tanperature technique. By adjusting the composition of the precursor solution along with the hydrolysis and polycondensation processes, the resnlting nanostructured blends exhibit different morphologies and surface chemical components. Fnjishima et al. reported [52] the wettability of TiO and other photocatalysts prepared by the sol-gel method. 

Monodispersed particles can form close packed assemblies on nanostructured blend surfaces because of van der Waals interactions. The particle assemblies provide roughness to the underlying substrates. Further treatment, such as plasma etching [77] can also be applied to improve the surface roughness of blends. The colloidal particles can vary from polymer blends to inorganic spheres. Colloidal assembly is cost effective, since no expensive lithographic technique is required. This method is easy to master and to apply under laboratory conditions. 

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