Preparation and some properties of organically modified layered alkali titanates with alkylmethoxysilanes

Ide, Yusuke; Ogawa, Makoto

doi:10.1016/j.jcis.2005.08.058

Cited by 40 publications

(32 citation statements)

References 51 publications

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“…The scan of the as received OMMT (Figure 3A) presents a reversible transition nearly located at 44°C (ΔH ≈26 J/g) that corresponds to the loss of rotator order of the hydrocarbon tails of the cations intercalated in the interlayer space. In this respect, it is worth adding that endothermic peaks corresponding to the loss of order in the packing of the hydrocarbon tails have been observed, in the temperature range 25–80°C, not only for cationic organoclays, (Cipolletti et al, 2013) but also for other organically modified layered inorganic structures (Ide and Ogawa, 2006) as well as for graphite oxide intercalation compounds (Mauro et al, 2013). The DSC scan of the scCO 2 treated OMMT does not present any thermal transition in the considered temperature range (Figure 3B) and hence indicates the loss of 3D order in the packing of the hydrocarbon tails of the ammonium surfactant, which is compatible with clay exfoliation.…”

Section: Resultsmentioning

confidence: 99%

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

et al. 2013

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Supercritical carbon dioxide (scCO2) treatments of a montmorillonite (MMT) intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT) led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS), have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

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Section: Resultsmentioning

confidence: 99%

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

et al. 2013

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“…The density of the two silyl groups in the interlayer space is controllable by changing the added amount of PTMS and C 18 TMS. [5,11] Figure 2 shows the adsorption isotherms of NPh for PTMS-C 18 TMS-TLO and KTLO. PTMS-C 18 TMS-TLO adsorbed NPh from aqueous solution; however, KTLO hardly adsorbed NPh.…”

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confidence: 99%

Interlayer Modification of a Layered Titanate with Two Kinds of Organic Functional Units for Molecule‐Specific Adsorption

Ide

Ogawa

2007

Angew Chem Int Ed

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Layered materials have widely been used as adsorbents, catalysts, catalyst supports, and hosts for functional molecular species, owing to 1) their large surface areas derived from well-defined nanostructures composed of ultrathin sheets, 2) their chemical stability, and 3) the diversity of the materials.[1] The modification of interlayer nanospaces has been conducted through ion exchange [2] and grafting.[3] Though there have been several examples in which the adsorptive characteristics of layered materials have been tuned by organic modification, [4] the ability to strongly and specifically bind a particular molecular species is still a topic of interest.We have reported that the organic derivative of a layered silicate that bears interlayer hydroxy groups and has been modified with controlled amounts of octyltrichlorosilane adsorbs n-alkyl alcohols and not n-alkanes.[5] This phenomenon was explained as the result of the cooperative effect of the chemical nature and geometry of the modified silicate, wherein the two functional units (alkyl and hydroxy groups) were spatially arranged to selectively bind n-alkyl alcohols. The immobilization of various kinds of organic functional units and the control of their spatial distribution in layered materials are worth further investigation to tailor guestbinding characteristics.Herein we report the immobilization of two different organic functional units, alkyl and phenyl groups, in the interlayer space of a layered titanate to specifically adsorb 4-nonylphenol (NPh), a known contaminant of water, from aqueous solution. The adsorption of NPh onto activated carbon [6] or a mesoporous organosilica [7] from aqueous solution has been reported, while the adsorption selectivity and capacity of NPh were not documented. In the system reported in this work, alkyl and phenyl groups were immobilized in the interlayer space to interact with the nonyl and phenyl groups of NPh, respectively.The adsorbent was synthesized as follows. Phenyltrimethoxysilane (PTMS) and n-octadecyltrimethoxysilane (C 18 TMS) were allowed sequentially to react with K 0.8 Ti 1.73 Li 0.27 O 4 (KTLO). The silylation of KTLO [8] was carried out by using the dodecyltrimethylammoniumexchanged form (C 12 TMA-TLO) as the intermediate. The silylation with PTMS was carried out by dispersing C 12 TMA-TLO (0.50 g) in a solution of PTMS (2.8 mL) in toluene (50 mL) and stirring the mixture for two days at 80 8C. The product was separated by centrifugation and washed with acetone. The phenylsilylated derivative (0.50 g) thus obtained (abbreviated as PTMS-TLO) was then dispersed in a solution of C 18 TMS (3.0 mL) in toluene (40 mL), and the mixture was stirred for two days at 80 8C. The product was separated by centrifugation and washed with acetone, a mixture consisting of HCl aq (0.1m, 20 mL) and ethanol (20 mL) to remove the remaining C 12 TMA, and finally a mixture of acetone (20 mL) and water (20 mL) to hydrolyze residual methoxy groups.[5]The silylated derivative thus obtained is abbreviated as PTMS-C 18 TMS-TLO. To...

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“…1 show that the layered titanate phase in the general formula A 2 Ti n O 2n+1 ÁH 2 O (A is Na + or H + , n = 2-8) is obtained in T120 sample. Na-or H-titanate has been commonly found in the materials prepared by the interaction between NaOH solution and titanium precursor without the subsequent acid treatment or washing [13][14][15]. Herein, a series of characteristic peaks at 9.8°, 24°, 28.1°and 48°corresponds to (2 0 0), (1 1 0), (3 1 0) and (0 2 0) diffractions.…”

Section: Shape Evolution and Properties Of Hierarchical Tio 2 Nanostrmentioning

confidence: 96%

Synthesis of hierarchical rose bridal bouquet- and humming-top-like TiO2 nanostructures and their shape-dependent degradation efficiency of dye

Nguyen‐Phan

Kim

Hahn

et al. 2011

Journal of Colloid and Interface Science

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Preparation and some properties of organically modified layered alkali titanates with alkylmethoxysilanes

Cited by 40 publications

References 51 publications

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

Interlayer Modification of a Layered Titanate with Two Kinds of Organic Functional Units for Molecule‐Specific Adsorption

Synthesis of hierarchical rose bridal bouquet- and humming-top-like TiO2 nanostructures and their shape-dependent degradation efficiency of dye

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