60021-86-5Relevant articles and documents
Model-based research toward design of innovative materials: Molecular weight prediction of bridged polysilsesquioxanes
Hamada, Takashi,Ishimoto, Takayoshi,Kai, Hiroyuki,Nakanishi, Yuki,Ohshita, Joji,Saito, Daiki,Sato, Kenji,Takase, Sakino,Tsukada, Satoru,Wakitani, Shin
, p. 28595 - 28602 (2020)
Toward the design and manipulation of innovative materials, we propose a new concept called "model-based research (MBR)". In MBR, measurable physical and chemical properties of materials are mathematically modelled by explanatory parameters obtained by computer simulation from an atomistic point of view. To demonstrate the potential of MBR, we modelled the molecular weights of a series of polysilsesquioxanes with respect to the H2O/silane molar ratio employed for the polymerization of monomers bis(triethoxysilyl)methane, ethane, ethylene, and acetylene (BTES-M, -E1, -E2, and -E3), as an example. The equation y = axn well reproduced the behaviour of the molecular weights of the BTES series, in which a and n were obtained using the calculated molecular parameters for monomers as the explanatory parameters. Detailed understanding and discussion were theoretically possible on the basis of the mathematical model. We predicted the molecular weights of polymers that would be obtained from monomers BTES-P and BTES-Ph with C3H6 and C6H4 as the spacer, respectively, using the mathematical model. Experimental validation of these polymers clearly showed the possibility of qualitative categorization. Our proposed concept, MBR, is a powerful tool to analyse materials science toward innovative materials design.
Manganese-Catalyzed Hydrofunctionalization of Alkenes
Carney, Jonathan R.,Dillon, Barry R.,Campbell, Leonie,Thomas, Stephen P.
supporting information, p. 10620 - 10624 (2018/07/31)
The manganese-catalyzed hydrosilylation and hydroboration of alkenes has been developed using a single manganese(II) precatalyst and reaction protocol. Both reactions proceed with excellent control of regioselectivity and in high yields across a variety of sterically and electronically differentiated substrates (25 examples). Alkoxide activation, using NaOtBu, was key to precatalyst activation and reactivity. Catalysis was achieved across various functional groups and on gram-scale for both the developed methodologies with catalysts loadings as low as 0.5 mol %.
Cyclization phenomena in the Sol-Gel polymerization of α,ω-bis(triethoxysilyl)alkanes and incorporation of the cyclic structures into network silsesquioxane polymers
Loy, Douglas A.,Carpenter, Joseph P.,Alam, Todd M.,Shaltout, Raef,Dorhout, Peter K.,Greaves, John,Small, James H.,Shea, Kenneth J.
, p. 5413 - 5425 (2007/10/03)
Intramolecular cyclizations during acid-catalyzed sol-gel polymerizations of α,ω-bis(triethoxysilyl)-alkanes substantially lengthen gel times for monomers with ethylene (1), propylene (2), and butylene (3) bridging groups. These cyclization reactions were found, using mass spectrometry and 29Si NMR spectroscopy, to lead preferentially to monomeric and dimeric products based on six- and seven-membered disilsesquioxane rings. 1,2-Bis(triethoxysilyl)ethane (1) reacts under acidic conditions to give a bicyclic dimer (5) that is composed of two annelated seven-membered rings. Under the same conditions, 1,3-bis(triethoxysilyl)propane (2), 1,4-bis(triethoxysilyl)butane (3), and Z-1,4-bis(triethoxysilyl)but-2-ene (10) undergo an intramolecular condensation reaction to give the six- and seven-membered cyclic disilsesquioxanes 6, 7, and 11. Subsequently, these cyclic monomers slowly react to form the tricyclic dimers 8, 9, and 12. With NaOH as polymerization catalyst, these cyclic silsesquioxanes readily reacted to afford gels that were shown by CP MAS 29Si NMR and infrared spectroscopies to retain some cyclic structures. Comparison of the porosity and microstructure of xerogels prepared from the cyclic monomers 6 and 7 with those of gels prepared directly from their acyclic precursors 2 and 3 indicates that the final pore structure of the xerogels is markedly dependent on the nature of the precursor. In addition, despite the fact that the monomeric cyclic disilsesquioxane species cannot be isolated from 1-3 under basic conditions due to their rapid rate of gelation, spectroscopic techniques also detected the presence of the cyclic structures in the resulting polymeric gels.
