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Tailoring a Thermally Stable Amorphous SiOC Structure for the Separation of Large Molecules: The Effect of Calcination Temperature on SiOC Structures and Gas Permeation Properties.

ABSTRACT: A SiOC membrane with high oxidative stability for gas separation was tailored by utilizing vinyltrimethoxysilane, triethoxysilane, and 1,1,3,3-tetramethyldisiloxane as Si precursors. Amorphous SiOC networks were formed via the condensation of Si-OH groups, the hydrosilylation of Si-H and Si-CH=CH2 groups, and a crosslinking reaction of Si-CH3 groups, respectively. The crosslinking of Si-CH3 groups at temperatures ranging from 600 to 700 °C under a N2 atmosphere was quite effective in constructing a Si-CH2-Si unit without the formation of mesopores, which was confirmed by the results of N2 adsorption and by the gas permeation properties. The network pore size of the SiOC membrane calcined at 700 °C under N2 showed high oxidative stability at 500 °C and was appropriate for the separation of large molecules (H2/CF4 selectivity: 640, H2/SF6: 2900, N2/CF4: 98). A SiOC membrane calcined at 800 °C showed H2/N2 selectivity of 62, which was approximately 10 times higher than that calcined at 700 °C because the SiOC networks were densified by the cleavage and redistribution reactions of Si-C and Si-O groups.

SUBMITTER: Inde H

PROVIDER: S-EPMC6644687 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Tailoring a Thermally Stable Amorphous SiOC Structure for the Separation of Large Molecules: The Effect of Calcination Temperature on SiOC Structures and Gas Permeation Properties.

Inde Hiroki H Kanezashi Masakoto M Nagasawa Hiroki H Nakaya Toshimi T Tsuru Toshinori T

ACS omega 20180613 6

A SiOC membrane with high oxidative stability for gas separation was tailored by utilizing vinyltrimethoxysilane, triethoxysilane, and 1,1,3,3-tetramethyldisiloxane as Si precursors. Amorphous SiOC networks were formed via the condensation of Si-OH groups, the hydrosilylation of Si-H and Si-CH=CH2 groups, and a crosslinking reaction of Si-CH3 groups, respectively. The crosslinking of Si-CH3 groups at temperatures ranging from 600 to 700 °C under a N2 a ...[more]

PMID: 31458820

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Project description:The maximum achievable concentration of a drug in solution is dictated by the chemical potential of the solid form. Because an amorphous solid has a higher chemical potential than the corresponding crystal form, in the absence of phase transformations, a higher transient solubility is expected. However, the chemical potential of an amorphous drug can be reduced by mixing with another component. Therefore, upon mixing with a polymer to form an amorphous solid dispersion (ASD), the maximum solution concentration achieved can be potentially altered, in particular if the polymer is poorly soluble in the dissolution medium. Such changes in the chemical potential of the drug may be a critical factor in determining the maximum achievable solution concentration, and could alter the crystallization driving force of the drug. Therefore, the aim of this study was to gain insights into the impact of poorly soluble polymers on the "amorphous solubility" of drugs formulated as amorphous solid dispersions. Lopinavir was selected as a model drug with a low crystallization tendency, enabling determination of the amorphous solubility as a function of ASD composition. Model polymers included cellulose acetate (CA), CA phthalate (CAP), ethylcellulose (EC), Eudragit® RL PO (EUD), hydroxypropylmethylcellulose (HPMC), HPMC acetate succinate (HPMCAS), and HPMC phthalate (HPMCP). The "amorphous solubility" of the drug alone was determined and then the changes in maximum achievable concentration were measured as a function of drug loading. Drug-polymer interactions were characterized using infrared spectroscopy (IR), differential scanning calorimetry (DSC) and moisture sorption analysis. The results showed that the maximum achievable concentration ("amorphous solubility") of lopinavir varied with the extent of drug-polymer interactions, as well as the drug weight fraction in the ASD. This information is of great value when evaluating the maximum achievable concentration of amorphous systems formulated with pH responsive polymers, and should contribute to a broader understanding of drug phase behavior in the context of ASDs.

Dataset Information

Tailoring a Thermally Stable Amorphous SiOC Structure for the Separation of Large Molecules: The Effect of Calcination Temperature on SiOC Structures and Gas Permeation Properties.

Publications

Tailoring a Thermally Stable Amorphous SiOC Structure for the Separation of Large Molecules: The Effect of Calcination Temperature on SiOC Structures and Gas Permeation Properties.

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