Layered Inorganic−Organic Talc-like Nanocomposites

Abstract

New layered inorganic-organic magnesium organosilicates were prepared by a singlestep template sol-gel synthesis through the reaction of magnesium ions with a synthetic homologous series of urea-alkoxysilanes with the general formula (CH 3 CH 2 O) 3 Si(CH 2 ) 3 -NHC(O)NH( CH 2 ) n CH 3 , for n ) 2, 4, and 6. The nanocomposites were characterized by elemental analysis, solid-state 29 Si and 13 C nuclear magnetic resonance, X-ray diffraction, and thermogravimetry. The results showed that the hybrid materials exhibit lamellar structures similar to those found in the natural inorganic silicate talc. The influence of the length of the organic group of the urea-alkoxysilane employed in the formation of these layered structures is clearly observed by 29 Si NMR spectroscopy. A high degree of condensation for the hybrid synthesized with urea-alkoxysilane containing the longest alkyl chain was obtained. These materials seem to be promising as sorbents for solid-phase extraction of organic pollutant molecules, when dispersed in water, because of their highly hydrophobic character.

Use of PP Grafted with Itaconic Acid as a New Compatibilizer for PP/Clay Nanocomposites

“…Surface modification of hydrophilic clays through ion exchange reaction, normally with long-chain alkylammonium ions increases the hydrophobic character as well as the interlayer spacing of these materials. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Therefore, the organically modified clays (O-clays) would be more compatible with non-polar polymers such as poly(propylene) (PP). However, in the case of PP, the main difficulty encountered in preparing nanocomposites with O-clays is the lack of sufficient interaction between the hydrophobic polyolefin matrix and still relatively hydrophilic O-clays.…”

“…[1,7,9,[15][16][17] However, depending on the hydrophilic/hydrophobic balance of a polymer, the polymer chains could enter into the interlayer space of the clay and form either tactoid, intercalated or an exfoliated nanocomposites. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In the tactoid hybrid structure, the polymer chains mainly surround the stacks of the clay resulting in a material with properties similar to those of microcomposites. In the intercalated hybrid structure, extended polymer chains are introduced between the silicate sheets, resulting in a multilayered structure consisting of alternating polymer and inorganic clay layers.…”

Silylation of clay mineral surfaces

“…On the other hand, in situ silylation technology was widely used in the synthesis of inorganic-organic hybrid phyllosilicates, such as 2:1 trioctahedral minerals (e.g., talc, hectorite and saponite) (Carrado, 2000;da Fonseca et al, 2000b;Fujii et al, 2003;Jaber et al, 2003;Silva et al, 2002), 2:1 dioctahedral minerals (e.g., pyrophyllite, beidellite and montmorillonite) (Jaber et al, 2005;Miehe-Brendle et al, 2010), and 1:1 minerals (e.g., kaolinite) (da Fonseca and Airoldi, 2000). The structure of inorganic-organic hybrid phyllosilicate strongly depended on the used metallic cations and organosilanes as silicon source in a sol-gel process.…”

Synthetic, layered nanoparticles for polymeric nanocomposites (PNCs)

“…In MAG and kenyaite an isomorphous substitution of Si with B and Al has been successfully performed, as well as them being grafted with organic or metallic ions. [73][74][75] Using trialkoxysilanes and inorganic salts in water solutions Schwieger et al prepared in a one-step method layered Al 3þ ,M g 2þ ,N i 2þ and Ca 2þ organosilicates using extremely mild conditions (aging for 24 hr at 408C). 76 Post-functionalization of the silicic acids by grafting on the surface silanol groups offers interesting prospects for their use in PNCs.…”