Silicone networks nanocomposites

Silicone co-polymer networks and IPNs have recently been reviewed.321 The development of IPNs is briefly described, and the definitions of the main (non-exclusive) classes of the IPNs are cited. Examples of latex IPNs, simultaneous and sequential IPNs, semi-IPNs, and thermoplastic IPNs are provided. The use of silicone-silicone IPNs in studies of model silicone networks is also illustrated. Networks in which siloxane and non-siloxane components are connected via chemical bonds are considered co-polymer networks, although some other names have been applied to such networks. Today, some of the examples in this category should, perhaps, be discussed as organic-inorganic hybrids, or nanocomposites. Silicone IPNs are discussed in almost all of the major references dealing with IPNs.322-324 Silicone IPNs are also briefly discussed in some other, previously cited, reviews.291,306... 

Hadjistamov (1999) examined the effect of nanoscale silica on the rheology of silicone oil and uncured epoxy-resin (araldite) systems. Shear thickening and yield-stress-like behaviour were observed and found to be due to a build-up of network structure associated with the nanocomposite phase. 

Leventis N, Sadekar A, Chandrasekaran N, Sotiriou-Leventis C (2010) Click synthesis of monolithic silicon carbide aerogels from poly acrylonitrile-coated 3D silica networks. Chem Mater 22 2790-2803 Boday D J, DeFriend K A, Wilson K V Jr, Coder D, Loy D A (2(X)8) Formation of polycyanoacrylate-sUica nanocomposites by chemical vapor deposition of cyanoacrylates on aerogels. Chem Mater 20 2845-2847 Boday D J, Stover R J, Muriithi B, Keller M W, Wertz J T, DeFriend Obrey K A, Loy D A (2009) Strong, low density nanocomposites by chemical vapor depositim and polymerization of cyanoacrylates on aminated siUca aerogels. ACS Appl Mater Interfaces 1 1364—1369... 

For several decades, carbon black and fumed silica have been used in tires, tubings, sealants and so on.[162,163] More recently, functionalized silica nanoparticles were reported to copolymerize with MMA to produce transparent films with good surface finish and controllable refractive index. [162] The sol-gel process is another research topic to prepare the polymer nanocomposites. The principal sol-gel process includes two steps the formation of a colloidal suspension, i.e. sol, and the gelation of the sol to formulate a network in a continuous liquid phase, i.e. gel. For example, the hydrolysis and poly condensation of silicon alkoxides in the presence of MMA will produce a polymer nanocomposite with superior optical and mechanical properties.[163]... 

The IR spectra of diamond-like carbon (DLC) films from dielectric barrier discharge plasma showed the presence (vCH) of CH3, CH2 and CH units in the approximate ratios 10 21 69. IR and Raman spectra were used to characterise DLC films on stainless steel or silicon substrates. Transmission IR spectra included bands due to v, and VasCH2 of sp CH2 units at 2870 and 2960 cm respectively. The FTIR spectrum of a diamond-like nanocomposite (DLN) film formed by thermally-activated CVD on a silicon substrate showed the presence of a diamond-like a-C a-Si 0 network. Several other papers described vibrational spectroscopic studies on diamond-like materials. ... 

Layered silicates belonging to the smectite clays family can be delaminated or exfoliated in the formation of the well-known polymer-clay nanocomposites initially developed by Fukushima and Inagaki at the Toyota Central Laboratories [54]. In a similar way, Letaief and Ruiz-Hitzky [55] using silicon alkoxides able to promote sol-gel processes have successfully achieved the hydrolysis and polycondensation of Si(OR)4 compounds within the interlayer space of smectite clays giving rise to a silica network with the concomitant delamination of the silicate layers [8,55-57]... 

Keywords Siliconized epoxy, phosphorus-containing bismaleimide, DOPO, POSS, antifouling coatings, nanocomposites, nanohybrid coatings, anticorrosive coatings, intercrosslinked networks, flame retardancy... 

Electrical conductivity of CNF/silicone nanocomposites has been investigated by few researchers [165, 167]. Roy et al. [165] observed that the percolation threshold is attained at 4 phr in-situ and ex-situ prepared CNF/PDMS nanocomposites. When amine-modified CNF is used as filler in PDMS, the percolation threshold appears at lower filler loading (1 phr). These studies have also shown that the electrical conductivity of PDMS and its nanocomposites follow the order neat PDMS (10 S cm ) < ex-situ PDMS/1 phr CNF (10" S cm ) < in-situ PDMS/1 phr CNF (10 S cm ) < in-situ PDMS/amine modified 1 phr CNF (10" S cm ). The higher electrical conductivity of amine-modified CNF-based PDMS nanocomposites could be assigned to the better dispersion of CNF facilitating the formation of conducting network. 

Figure 18.17 shows the solid-state Si NMR spectra of the modified hybrid nanocomposite. Condensed siloxane species for TEOS, the silica network structure of the hybrid nanocomposite in which a silicon atom through mono-,... 

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