Poly -silica hybrids

As an organic polymer, poly(tetramethylene oxide) was also used for the preparation of ceramers. The mechanical properties in these cases were much improved in comparison with those for hybrids from polysiloxanes. In these poly (tetramethylene oxide)-silica hybrids, the effect of the number of functional triethoxysilyl groups was examined [13]. As shown in Fig. 2, more multifunctional organic polymer produced more crosslinked hybrid networks. This means that the more rigid the structure in the hybrids is, the higher the modulus and the lower swelling property. 

By using a similar procedure for the preparation of hybrids of silica, hybrids materials consisting of other metal oxides were also prepared by the group of Wilkes [15]. For example, titania was incorporated into organic polymers by using the chemically controlled condensation (CCC) method for the preparation of poly(tetramethylene oxide)-silica or poly(dimethylsiloxane)-silica hybrids. Especially, in the case of the hybrid with poly (tetramethylene oxide), the modulus or ultimate strength of the hybrid increased in the presence of titania component, as shown in Table 3. This phenomenon was explained by the catalytic ability of... 

Tian et al. [56] have studied poly(G-caprolactone)-silica and Sengupta et al. [57] have investigated nylon 66-silica hybrid systems and have observed that the phase separation started when Si/H20 mole ratio is increased above 2 and the resultant hybrid films become opaque. Gao [11] has reported similar observations on sol-gel-derived ionomeric polyethylene-silica system. A wide range of literatures is not available on this topic of mbber-silica hybrid nanocomposites, though Bandyopadhyay et al. [34,35] have reported the hybrid formation with different TEOS/H2O mole ratios from ACM and ENR and also demonstrated detailed structure-property correlation in these systems. The hybrids have been prepared with 1 1, 1 2, 1 4, 1 6, 1 8, and 1 10 TEOS/H2O mole ratios. Figure 3.14 shows the morphology of the ACM-silica hybrid composites prepared from different TEOS/H2O mole ratios. 

Preparation of a bioactive and degradable poly(epsilon-caprolactone) / silica hybrid through a sol-gel method. Biomaterials, 23, 4915-4921. 

Although the biocompatibility and biodegradability of these materials were rapidly determined, the bioactivity of Si02-PCL hybrid materials was not studied until recently [99]. In order to provide bioactivity to Si02-PCL hybrid materials, Rhee prepared triethoxysilane end-capped poly(s-caprolactone) which was then cocondensed with tetraethyl orthosilicate and calcium nitrate via the sol-gel method. The Ca-containing PCL/silica hybrid so obtained showed in vitro bioactivity and biodegradability. The hybridization procedure between the a,co-hydroxyl PCL and silica phases was proposed to be as follows ... 

Chen, Q Miyata, N. and Kokubo, T. (2003) Bioactivity and mechanical properties of poly (dimethylsiloxane) modified calcia-silica hybrids with added titania. Journal of the American Ceramic Society, 86, 806-810. 

Rhee, S.H. (2004) Bone-like apatiteforming ability and mechanical properties of poly(e-caprolactone)/silica hybrid as a function of poly (e-caprolactone) content Biomaterials, 25, 1167-1175. 

Organic-silica hybrid materials have been used for multi-photon microfabrication. These include the acrylate-functionalized oligosiloxanes known as ORMOCERs, which have been polymerized by radical processes using conventional IP radical iniatitors, such as c.2 [221,234]. Commercial poly(dimethylsiloxane)-based resists containing vinyl and Si-H functionalities use two different 2PA-induced processes hydrosilylation catalyzed by the photodecomposition products of Cp PtMes (Cp = ti -methylcyclopentadienyl) and radical initiation by c.4 (Fig. 13) [235]. The former process was complicated by thermally-induced polymerization. 

The chemical entrapment of TEMPO moiety in the sol-gel silica hybrid material is performed in two steps reductive amination of 4-oxo-TEMPO with 3-aminopropyl-trimethoxysilane (APTMS) followed by sol-gel co-poly-condensation of the TEMPO-funcionalized alkoxide thereby obtained with methyl-trimethoxysilane (MTMS) catalyzed by fluoride (Figure 6.2). 

Figure 4 Polymer-silica hybrid materials hydrogen bonding between silanol groups of hydrolyzed silicon alkoxides and carboxylate groups of preformed poly(A, A-dimethylacrylamide) (a) or in situ polymerized A, A-dimethylacrylamide/methylene bisacrylamide precursors (b) favors the formation of homogeneous organic-inorganic networks...

Me K, Pang W, Wang Y, Lu F, Zhu Q (2005) Effects of specific bonding interactions in poly (8-caprolactone)/silica hybrid materials on optical transparency and melting behavior. Matra-... 

Ogoshi, T., Chujo, Y., (2005) Synthesis of poly(vinylidene fluoride) (PVdF)/silica hybrids having interpenetrating polymer network structure by using crystallization between PVdF chains. Polymer Science Part A, Polymer Chemistry, Vol. 43, No. 16, pp. 3543-3550, ISSN 1099-0518. 

Wang ED, Zhao TS, Yang WW (2010) Poly(vinyl alcohol)/3-(trimethyl ammonium (propyl-functionalized silica hybrid membranes for alkaline direct ethanol fuel cells. Int J Hydrogen Energ 35 2183-2189... 

Kim DS, Shin KH, Park HB, Lee YM (2004) Preparation and characterization of sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK)/silica hybrid membranes for direct methanol fuel cell applications. Macromol Res 12 413-421... 

He, Z., Pinnau, I. and Morisato, A. 2002. Nanostructured poly(4-methyl-2-pentyne)/silica hybrid membranes for gas separation. 146(1-3) 11-15. 

Lee, T, Park, S.S., Jung, Y. et al. 2009. Preparation and characterization of polyimide/mesoporous silica hybrid nanocomposites based on water-soluble poly(amic acid) ammonium salt. Eur. Polytn. J. 45 19-29. 

Lim JS, Noda I, hn SS (2007) Effect of hydrogen bonding on the crystallization behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/silica hybrid composites. Polymer 48 (9) 2745-2754... 

Sugimoto H, Daimatsu K, Nakanishi E, Ogasawara Y, Yasumura T, Inomata K (2006) Preparation and properties of poly(methylmethacrylate)-silica hybrid materials incorporating reactive silica nanoparticles. Polymer 47(11) 3754—3759... 

Kim JH, Lee YM (2001) Gas permeation properties of poly(amide-6-b-ethylene oxide)-silica hybrid membranes. J Membr Sci 193(2) 209-225... 

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