• Title, Summary, Keyword: organic template

Search Result 72, Processing Time 0.041 seconds

Effect of Template Removal on Synthesis of Organic-Inorganic Hybrid Mesoporous MCM-48

  • Zhao, Ya Nan;Li, San Xi;Han, Chong-Soo
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.10
    • /
    • pp.3196-3202
    • /
    • 2012
  • Post-synthesis is used to synthesize organic hybrid inorganic mesoporous sieves. In this method, the activity and structure of the base sieve are crucial to obtain the definable hybrid materials. The chemical and physical properties of the base can be largely changed either by the final step of its synthesizing processes, by template removal which is accomplished with the oxidative thermal decomposition (burning) method or by solvent extraction method. In this paper we compared two methods for the post-synthesis of organic hybrid MCM-48. When the template was extracted with HCl/alcohol mixture, the final product showed larger pore size, larger pore volume and better crystallinity compared to the case of the thermal decomposition. The reactivity of the surface silanol group of template free MCM-48 was also checked with an alkylsilylation reagent $CH_2=CHSi(OC_2H_5)_3$. Raman and $^{29}Si$ NMR spectra of MCM-48 in the test reaction indicated that more of the organic group was grafted to the surface of the sample after the template was removed with the solvent extraction method. Direct synthesis of vinyl-MCM-48 was also investigated and its characteristics were compared with the case of post-synthesis. From the results, it was suggested that the structure and chemical reactivity can be maintained in the solvent extraction method and that organic grafting after the solvent extraction can be a good candidate to synthesize a definable hybrid porous material.

Polymeric Materials for Molecular Recognition

  • Ki, Chang-Do;Lee, Kang-Won;Chang, Ji-Young
    • Proceedings of the Polymer Society of Korea Conference
    • /
    • /
    • pp.172-172
    • /
    • 2006
  • Molecular imprinting constitutes a valuable method of preparing polymeric materials with specific binding properties. The most conspicuous merit of molecular imprinting is that structurally three-dimensional recognition sites can be introduced into a polymer matrix with ease and low cost when compared with the complicated process of biological system for antigen and antibody. We used a thermally reversible bond for the preparation of the monomer-template complex, which allowed us to remove the template easily by means of a simple thermal reaction and to simultaneously introduce various functional groups into the cavity. This method is especially propitious for developing artificial receptors for molecules lacking strongly interactive groups.

  • PDF

Fabrication of 3-Dimensional LiMn2O4 Thin Film

  • Park, Bo-Gun;Ryu, Jea Hyeok;Choi, Won Youl;Park, Yong-Joon
    • Bulletin of the Korean Chemical Society
    • /
    • v.30 no.3
    • /
    • pp.653-656
    • /
    • 2009
  • 3-Dimensionally ordered macroporous $LiMn_2O_4$ thin film was prepared by a sol-gel and dip coating method on Pt/Ti/$SiO_2$/Si substrate. An opal structure consisting of mono dispersed polystyrene beads (300 nm) was used as a template. After solution containing Mn and Li precursors was coated on the template-deposited substrate, the template and organic materials in the precursors was removed by calcination at 400 ${^{\circ}C}$. And then the 3-dimensional $LiMn_2O_4$ thin film with spinel structure was fabricated by heat treatment at 700 ${^{\circ}C}$. The structural and electrochemical property was investigated by XRD, SEM and charge-discharge cycler.

Fabrication of Conducting Polymer Nanomaterials Using Soft Template Method

  • Jang, Jyong-Sik
    • Proceedings of the Polymer Society of Korea Conference
    • /
    • /
    • pp.76-77
    • /
    • 2006
  • Conducting polymers have been attracting considerable attention from both scientific and industrial perspectives by virtue of the beneficial electrical and optical properties originating from their unique ${\pi}-conjugated$ system. Many efforts have been devoted toward fabricating conducting polymer nanomaterials. Of the various synthetic methodologies, soft template method has emerged as a very promising tool in fabricating conducting polymer nanomaterials. For last a few years, our research group has intensively studied the fabrication and application of conducting polymer nanomaterials. In this talk, the recent achievement in the synthetic methodology based on the use of soft templates will be discussed.

  • PDF

Surface modified nanostructured-TiO2 thin films for removal of Congo red

  • Tiwari, Alka;Shukla, Alok;Choi, Suk Soon;Lee, Seung-Mok
    • The Korean Journal of Chemical Engineering
    • /
    • v.35 no.10
    • /
    • pp.2133-2137
    • /
    • 2018
  • We synthesized nanostructured $TiO_2$ thin films by the modified sol-gel template method using the polyethylene glycol as filler media. The $TiO_2$ surface modification for both the thin films, i.e., template and non-template, was done with the ascorbic acid. All the four thin film samples, S1 ($TiO_2$ (non-template), $TiO_2$ (template), S3 (S1 modified with ascorbic acid) and S4 (S2 modified with ascorbic acid), were characterized by various analytical methods. Phase evaluation was monitored by the X-Ray diffraction analysis. Moreover, the thin films particle sizes were obtained to be 22.32, 21.20, 14.52 and 16.77 nm, respectively for the samples S1, S2, S3 and S4. The changes in particle size and morphology due to the PEG and ascorbic acid were determined by scanning electron microscopy (SEM). Similarly, thermal gravimetric (TG) and differential scanning calorimetry (DSC) were performed to determine the decomposition behavior of organic compound present in the solid samples. The functional groups were determined by infrared (IR) analysis. The photocatalytic efficiency, as a reference of Congo red, was conducted using all the four samples of $TiO_2$ thin films. Complete photocatalytic degradation of Congo red was achieved by these samples within 130, 80, 40 and 30 mins of UV illumination.

Preparation of Silica Monoliths with Macropores and Mesopores and of High Specific Surface Area with Low Shrinkage using a Template Induced Method

  • Guo, Jianyu;Lu, Yan;Whiting, Roger
    • Bulletin of the Korean Chemical Society
    • /
    • v.34 no.2
    • /
    • pp.447-452
    • /
    • 2013
  • In this study we report a new method for the synthesis of a silica monolithic column bed with bimodal pores (throughpores and mesopores). The template induced synthesis method was used to direct bimodal pores simultaneously instead of the usual post base-treating method. Block polymer Pluronic F127 was chosen as a dual-function template to form hierarchically porous silica monolith with both macropores and mesopores. This is a simplification of the method of monolithic column preparation. Poly(ethylene glycol) was used as a partial substitute for F127 can effectively prevent shrinkage during the monolith aging process without losing much surface area (944 $m^2/g$ to 807 $m^2/g$). More importantly, the resultant material showed a much narrower mesopore size (centered at 6 nm) distribution than that made using only F127 as the template reagent, which helps the mass transfer process. The solvent washing method was used to remove the remaining organic template, and it was proved to be effective enough. The new synthesis method makes the fabrication of the silica monolithic column (especially capillary column) much easier. All the structure parameters indicate that monolith PFA05 prepared by the above method is a good material for separation, with the merits of much higher surface area than usual commercial HPLC silica particles, suitable mesopore volume, narrow mesopore size distribution, low shrinkage and it is easily prepared.

Synthesis and Characterization of Methyltriethoxysilyl-Mediated Mesoporous Silicalites

  • Rabbani, Mohammad Mahbub;Oh, Weon-Tae;Nam, Dae-Geun
    • Transactions on Electrical and Electronic Materials
    • /
    • v.12 no.3
    • /
    • pp.119-122
    • /
    • 2011
  • A series of mesoporous silicalites was synthesized using different compositions of tetraethylorthosilicate and methyltriethoxysilane (MTES) as the silica source. Cetyltrimethylammonium bromide was used as the organic template. Their detailed pore structures were investigated by transmission electron microscopy, X-ray diffraction, and N2 adsorption method. The thermal properties of these silicalites were studied by thermogravimetric analysis. The increased amount of MTES destroyed mesoporous channels and reduced pore sizes from 3.4 nm to 2.8 nm in calcined silicalites. The calcined silicalite transformed completely into an amorphous state at 30% MTES loading. Methyl pending groups of MTES hindered the structural ordering of ≡Si-O- frameworks, resulting in an amorphous structure. This was caused by the insufficient formation of supramolecular assembly with the organic template. No capillary condensation step was found in MS 7/3 silicalite. The other capillary condensation steps shifted toward the lower relative pressure with increasing MTES content, indicating the reduction of pore sizes.

Synthesis of Hollow Silica Particles from Sodium Silicate using Organic Template Particles (유기 주형 입자를 이용한 소디움 실리케이트로부터 중공형 실리카 입자 제조)

  • Lee, Chongmin;Kim, Jiwoong;Chang, Hankwon;Roh, Ki-Min;Jang, Hee Dong
    • Korean Chemical Engineering Research
    • /
    • v.53 no.1
    • /
    • pp.78-82
    • /
    • 2015
  • Hollow silica particles were prepared using sodium silicate and organic templates. Polystyrene latex (PSL) particles produced by dispersion polymerization were used as organic templates. PSL particles ranged from $1{\mu}m$ to $3{\mu}m$ in diameter were synthesized by adjusting the amount of 2,2'-azobisisobutyronitrile (AIBN). The PSL/$SiO_2$ core-shell particles were prepared by coating of silica nanoparticles originated from sodium silicate using sol-gel method. The organic templates were removed by the organic solvent, tetrahydrofuran (THF). Morphology of hollow silica particles was investigated with respect to types of the reaction medium and pH during the process. By changing the solvent from ethanol to water, hollow silica particles were successfully formed. Hollow silica particles with the uniform shell thickness were produced at low pH as well. The reflectivity of the as-prepared silica particles was measured in the range of the wavelength of UV and visible light. Hollow silica particles showed much better reflective properties than the commercial light reflector, Insuladd.

Effect of the Buffered-template on the Property of YBCO Superconducting Film Deposited by MOCVD Method (MOCVD 법에 의해 제조된 YBCO 초전도 박막의 물성에 대한 완충층 템플릿의 영향)

  • Jun, Byung-Hyuk;Choi, Jun-Kyu;Kim, Chan-Joong
    • Progress in Superconductivity
    • /
    • v.8 no.1
    • /
    • pp.27-32
    • /
    • 2006
  • [$YBa_2Cu_3O_{7-x}$] thin films were deposited on various buffered-templates by a metal organic chemical vapor deposition(MOCVD). Three different templates of $CeO_2/YSZ/CeO_2/pure-Ni(CYC),\;CeO_2/YSZ/Y_2O_3/Ni-3at.%W(YYC)$ and $CeO_2/IBAD-YSZ$/stainless steel were used. The Ni and Ni-W alloy tapes were biaxially textured by cold rolling and annealing heat treatment. The dense YBCO films were grown on both the IBAD and YYC templates with no microcrack, while the YBCO films on the CYC templates were grown with the formation of microcracks and NiO. The YBCO film on the YYC template showed the higher $I_c$ than that on CYC template. Especially, the IBAD templates with a thin $CeO_2$(type I) and thick $CeO_2$(type II) top layer were used to compare the deposition nature of the YBCO on them. Comparing the current property of the YBCO films on IBAD templates, the YBCO film deposited on thick $CeO_2$ layer was better than the film on thin $CeO_2$ layer.

  • PDF