Anionic surfactant-templated

S. Che, A.E. Garcia-Bennett, T. Yokoi, K. Sakamoto, H. Kunieda, O. Terasaki, and T. Tatsumi, A Novel Anionic Surfactant Templating Route for Synthesizing Mesoporous Silica with Unique Structure. Nature Mater. (London), 2003, 2, 801-805. 

The AMS (anionic surfactant-templated mesoporous silicas) materi-aisi30,i40,i42 family of well-ordered organosilicas prepared using anionic... 

O., and Tatsumi, T. (2003) A novel anionic surfactant templating route for synthesizing mesoporous silica with unique structure. Nat. Mater., 2, 801-805. 

Che, S., Garcia-Bennett, A.E., Yokoi, T., Sakamoto, K., Kunieda, H., Terasaki, O., and Tatsumi, T. (2003) A novel anionic surfactant templating route for synthesizing mesoporous silica with unique structure. Nat. Mater., 2 (12), 801-805. 

Scheme 16.6 Ionic interactions between anionic surfactant and cationic costructuredirecting agent (CSDA) in the synthesis of anionic surfactant template mesoporous silica (AMS). (Adapted from Ref. [100].)...

Mesoporous zirconia has been prepared using anionic surfactants containing reactive oxygens that could bind Zr2+ (224-226). Mesoporous zirconia was obtained using alkyl phosphate amphiphiles but they were not stable to template removal. 

Hybrid silica materials were prepared via a sol-gel pathway at pH 9. The influence of anionic surfactant (SDS) was studied by comparing templated materials (TbSn series) with hybrid materials obtained without surfactant (Tbn series). Two mechanisms of mesostructure formation can be considered as represented on Fig. 2. The pka of aminopropyl chain is about 10.6 in the reaction mixture propyl-amines are partially protonated. Electrostatic interactions between dodecylsulfate anion and NH and sodium cation neutralization may then occur, resulting in the condensation of the silica structure around surfactant micelles and aminopropyl groups at the surface of the pores. The other mechanism is SDS chains complex-ation by P-CD cavity, which wonld result in P-CD gronps located at the surface of the pores and aminopropyl less accessible, due to steric hindrance caused by P-CD bulky groups. A complete characterization of the prodncts and adsorption capacities will help nnderstanding the formation mechanism of mesoporons hybrid silica. 

This may be explained as follows the SDS interacts with the maximum of partially protonated aminopropyl groups, by electrostatic interactions between dodecylsulfate anion and and sodium cation neutralization. The remaining amino groups are entrapped into the silica network. The amount of P-CD moieties incorporated depend on the initial molar ratio of P-CD APS, and not of the presence or not of SDS. P-CD groups may not interact with SDS. We can say, that for these hybrid materials, the templated mechanism is a S P one (S for anionic surfactant, P for cationic aminosilica species). 

C) Use a mixture of cationic and anionic surfactants. Li synthesized MCM-48 using a mixture of CTAB and Ci2H25COONa as template.1126 The pair of cationic and anionic surfactants has higher hydrophobicity compared with a pure cationic surfactant. The pair prefer to penetrate to the core of the micelle to a certain degree, increase the packing parameter g. 

In the S I+ direct-synthesis pathway, anionic surfactants are used as templates for mesoporous metal oxides. For example, C12H25OSOT Na+ (SDS) as template for A1203 and Ga203 mesoporous materials with Ali3[A104Ali2(0H)24(H20)i27+] and Gai3-Keg-gin [Ga04Ali2(0H)24(H20)127+] as A1 and Ga source, respectively.11841... 

F.X. Chen, L.M. Huang, and Q.Z. Li, Synthesis of MCM-48 using Mixed Cationic-Anionic Surfactants as Templates. Chem. Mater., 1997, 9, 2685-2686. 

The PCM model can, as shown, also be used to describe the effect of other anions, surfactants, or chelates, e.g., with fatty acid templates. If 5(RH) < 0 (e.g., for an acetate group), it will remain in the gel produced and must be removed by pyrolysis, extraction, or some other means. We shall return to this matter when discussing the use of templates in the sol-gel processing of porous particles and gels. 

Besides polyanions such as SPS, anionic surfactants were able to provide the negative charges needed to template the formation of electrically conductive PANI. Indeed, micelles of sodium dodecylbenzensulfonate (SDBS) were used successfully as templates to induce the formation of linear and electrically conductive PANI [38]. On the other hand, cationic and non-ionic surfactants did not provide the negative charges and low pH environment needed for the synthesis of conducting PANI, as expected. Using a similar approach, dodecyl dipheny-loxide disulfonate (DODD) was used as a bifunctional template for the enzymatic synthesis of PANI [39]. UV-Vis and electrical conductivity studies showed that the electrically-conducting form of PANI was only obtained above the critical micellar concentration (CMC) of DODD. The bifunctional nature of the DODD provided... 

The surfactant templated synthesis of mesoporous ceramics was first reported in 1992 [1], and since that time there has been a veritable explosion in the number of papers in the area. There has been particular interest in the functionalization of mesoporous ceramics [2-S]. As outlined in Figure 1, the original synthesis employed rod-shaped micelles composed of cationic surfactant molecules as the pore template (more recently, this methodology has been extended to a wide variety of other surfactant systems and reaction conditions). When exposed to routine sol-gel conditions, the cationic micelles undergo an anionic metathesis with silicate anions, resulting in a glass-coated log which... 

By combining measurements of the repeat spacing from XRD measurements and pore diameters from one of the above techniques, or from modelling of the intensities of XRD peaks, the wall thickness of these materials can be calculated. The wall thicknesses of materials templated using neutral surfactants with EO headgroups, in particular the triblock copolymers such as the Pluronic series are much greater than those templated using small molecule cationic or anionic surfactants. Early measurements of the wall thicknesses of MCM-41 and MCM-48 found a width of about 8 A, equivalent to about two layers of tetrahedral SiOi units. ... 

Yada. M. Kitamura. H. Machida. M. Kijima, T. Yttrium-based porous materials templated by anionic surfactant assemblies. Inorg. Chem. 1998. 37. 6470. 

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