Mechanical Properties and Interface Characteristics of Nanoporous Low-<i>k</i>Materials

Si, Lina; Guo, Dan; Luo, Jianbin

doi:10.1021/am503236m

Cited by 23 publications

(18 citation statements)

References 53 publications

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“…For every step, the trial movement was chosen randomly with a fixed probability, which was 20% guest molecule translation, 20% guest molecule rotation, 55% guest molecule exchange, and 15% guest molecule regrowth. The Ewald summation method , was used to calculate the electrostatic potential energy with the calculation accuracy of 4.184 kJ/mol. The cut-off distance was 12 Å .…”

Section: Models and Methodsmentioning

confidence: 99%

Loading Dependence of the Adsorption Mechanism of Thiophene in FAU Zeolite

Dang

Zhao

Gao

et al. 2016

Ind. Eng. Chem. Res.

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In desulfurization-related researchers, thiophene is widely studied in adsorption, separation, and catalysis processes as a typical sulfur-containing compound. However, the adsorption behavior of thiophene for the very first step of all processes still remains ambiguous. In this study, we proposed the loading dependence of the adsorption mechanism of thiophene in siliceous faujasite (FAU) zeolite using Monte Carlo simulations combined with the research of adsorption isotherms, density distributions, concentration profiles, radial distribution functions, and interaction energies. The results revealed that the thiophene adsorption mechanism in the whole loading range could be divided into two parts: "ideal adsorption" and "insertion adsorption", with the inflection point of the loading at 40 molecules/UC, which was similar to the adsorption of monoaromatics in zeolite. Below the inflection point, adsorbed thiophene distributed broadly and mainly occupied S and W adsorption sites ideally; after the inflection point, newly adsorbed thiophene molecules entered into the space near the center of the supercage with no influence on previously adsorbed ones. As the loading of thiophene increased, the adsorption amount on the S sites went up consistently over the entire loading range. By contrast, the adsorption amount on the W sites grew first and then dropped gradually for loadings below the inflection point. Finally, it decreased noticeably with loading close to saturated adsorption. In addition, the occurrence of the inflection point was due to the change of the dominated interaction energy.

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Section: Models and Methodsmentioning

confidence: 99%

Loading Dependence of the Adsorption Mechanism of Thiophene in FAU Zeolite

Dang

Zhao

Gao

et al. 2016

Ind. Eng. Chem. Res.

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“…For example, polytetrafluoroethylene (PTFE) is a satisfactory low dielectric material used at high frequency because it shows the lowest D k (2.0) and lowest D f (near 1 × 10 –4 ) at a broad range of frequencies. ,, Nevertheless, PTFE always shows poor processability and has an inert surface, which hinder its application as the laminating resin for the production of the high-frequency printed circuit boards (PCB). On the other hand, generating holes in polymers to form porous materials is also an effective way for the production of low D k materials. − However, how to precisely control the sizes and distribution of the pores is a challenging task. Moreover, the mechanical properties and thermostability of the porous materials need to be improved.…”

Section: Introductionmentioning

confidence: 99%

A New Fluorinated Polysiloxane with Good Optical Properties and Low Dielectric Constant at High Frequency Based on Easily Available Tetraethoxysilane (TEOS)

et al. 2017

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A novel fluorinated macromonomer (TFVE-Si) with four functional groups derived from easily available tetraethoxysilane (TEOS) has been successfully synthesized through the Piers–Rubinsztajn reaction using B(C6F5)3 as a catalyst. This procedure efficiently avoids the generation of Si–OH and −Si–CH2–CH2– groups, which greatly affect the properties of the organosiloxanes. Prepolymerizing the macromonomer in mesitylene solution gives an oligomer which can form a flexible and highly transparent free-standing cross-linked polysiloxane film followed by a postpolymerization procedure at high temperature. The cross-linked polysiloxane (thickness = 2 mm) shows a transmittance of higher than 91% in the visible region and an absorbance of near 100% in the UV region (<350 nm), exhibiting its potential application as a transparent coating for blocking ultraviolet rays in both household and industrial uses. In particular, the cross-linked film shows low dielectric constant (D k ) of 2.50 and low dissipation factor (D f ) of 4.0 × 10–3 at an ultrahigh frequency of 10 GHz. This is the first example of nonporous polysiloxane having both low D k and D f while conventional TEOS-based polymers exhibit higher D k (>3.0). Moreover, D–E loop tests illustrate that the cross-linked polysiloxane possesses excellent linear dielectric properties, further suggesting its good insulating properties. Furthermore, the prepared polysiloxane exhibits high thermostability with a 5 wt % loss temperature of 476 °C and a glass transition temperature (T g) of 110 °C as well as good mechanical strength (with an elastic modulus of 1.1 GPa). Because of the existence of fluoro-containing groups, the polysiloxane also shows high hydrophobicity. Furthermore, TFVE-Si can efficiently improve the T g of linear polysiloxane prepared from dimethylsiloxane with two functional groups. These indicate that the fluorinated TEOS has potential application in the microelectronics industry; especially, it can meet the requirement of the high-frequency communication fields for the materials with both low D k and D f .

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“…The charges of O II ( q (O II ) = −0.67 |e|) were restricted by the relation: 2( q (O II ) + q (H)) = q (O I ) to preserve the neutrality of the zeolite lattice. The charges of benzene were chosen as the same with most common charges: hydrogen atoms carry a charge of +0.153 |e| and carbon atoms a charge of −0.153 |e|. − The summation methods of van der Waals interactions and electrostatic interactions were applied as atom-based and Ewald, respectively. − The cutoff value of van der Waals interaction was set as large as 2.4 nm, and the calculation accuracy of electrostatic potential energy was 0.004 kJ/mol. All the simulations are applied with the periodic boundary conditions. , …”

Section: Models and Methodsmentioning

confidence: 99%

Insight into the Contribution of Isolated Mesopore on Diffusion in Hierarchical Zeolites: The Effect of Temperature

Zheng

Zhai

Zhao

et al. 2018

Ind. Eng. Chem. Res.

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In recent years, hierarchical zeolites are becoming more and more attractive as a solution to the diffusion restraint of classical zeolites. There have been many theoretical as well as experimental developments that deepened our understanding of mass transfer phenomena in hierarchical materials. However, there appears to be no consensus on the role that disconnected mesopores played in molecular transport. In this paper, molecular simulation is conducted to study the diffusion of benzene in purely microporous FAU zeolite and hierarchical FAU models which consist of both microporosities of FAU and a cylindrical mesopore with various radiuses (0.74–17.5 nm) at 300–800 K. The usage of the disconnected mesopores at moderate adsorbate loading is testified on the molecular level. In fact, under the reaction temperature of catalytic reactions, the disconnected mesoporous are likely to be fully utilized and beneficial to the reaction process. The temperature dependence illustrated shows a remarkably good agreement between the theoretical predictions and the experimental results. It therefore confirms that the disconnected mesopore may weaken and subdue the resistance of diffusion at high temperatures at moderate loading. Based on a thorough quantitative analysis of the adsorption interactions, the mechanisms leading to these phenomena are further explained.

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Mechanical Properties and Interface Characteristics of Nanoporous Low-kMaterials

Cited by 23 publications

References 53 publications

Loading Dependence of the Adsorption Mechanism of Thiophene in FAU Zeolite

Loading Dependence of the Adsorption Mechanism of Thiophene in FAU Zeolite

A New Fluorinated Polysiloxane with Good Optical Properties and Low Dielectric Constant at High Frequency Based on Easily Available Tetraethoxysilane (TEOS)

Insight into the Contribution of Isolated Mesopore on Diffusion in Hierarchical Zeolites: The Effect of Temperature

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