Polysiloxane depolymerization with dimethyl carbonate using alkali metal halide catalysts

Okamoto, Masaki; Suzuki, Sukeji; Suzuki, Eiichi

doi:10.1016/j.apcata.2003.11.005

Cited by 53 publications

(61 citation statements)

References 16 publications

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“…It was found from previous work in the literature [2,3] that ion contamination can cause depolymerization in silicate films [2,3], which then could possibly lead to weight loss or polymer rearrangement. To determine whether our films could be impacted by ion contamination, the formulations were analyzed for residual metals.…”

Section: Experimental Results and Definition Of Issuesmentioning

confidence: 98%

Performance properties in thick film silicate dielectric layers using molecular modeling

Iwamoto

Krishnamoorthy

Spear

2009

Microelectronics Reliability

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Section: Experimental Results and Definition Of Issuesmentioning

confidence: 98%

Performance properties in thick film silicate dielectric layers using molecular modeling

Iwamoto

Krishnamoorthy

Spear

2009

Microelectronics Reliability

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“…Depending on the thermal depolymerization conditions, the modifying layer may comprise loops and free oligomeric chains with a secondary silanol at the ends. The use of dimethyl carbonate as a scission or depolymerization agent for polysiloxane was firstly proposed by authors [20].…”

Section: Introductionmentioning

confidence: 99%

DSC study of silicas with immobilized polysiloxane layer of different architecture

Bolbukh

Koutsoumpis

Georgopoulos

et al. 2016

J Therm Anal Calorim

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Core-shell structured nanocomposites of polydimethylsiloxane with different polymerization degree (PMS100 and PMS50) and polymethylphenylsiloxane (PMPS4) immobilized onto fumed silica nanoparticles were studied by means of differential scanning calorimetry. The polysiloxanes were attached to the particles' surface using thermally stimulated binding and modification in the presence of depolymerization activator-dimethyl carbonate (DMC). Single-and multi-stage processes were applied in order to obtain a different architecture of polymeric layer on the silica nanoparticles surface. The effect of polysiloxane/DMC ratio on phase transitions of obtained polymeric layers was evaluated. The grafting of polydimethylsiloxane at the presence of chain scissor resulted in cross-linking of the attached polymeric layers. When using a multi-step modification with PMPS, a dense crosslinked layer was formed on the silica surface. Unlike the samples obtained by one-step modification with different polymer content, for which the amount of polymer attached to silica surface changes the parameters of the relaxation process in polymeric layer, for composites synthesized using multi-stage modification, a greater influence has the length of the oligomer introduced on first stage. The best results were achieved for composite with PMPS when using on the first stage of modification the PMPS/DMC mixture with low content of depolymerization agent (oligomers with long chain, respectively). A notable increase in the mobility of the polymeric layer was detected due to the formation of isotactic macromolecular chains.

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“…Dialkyl carbonates are environmentally friendly reagents that meet all the requirements of green chemistry [31,32]. Japanese researchers showed that dimethyl or diethyl carbonate methanol solutions with the addition of alkali metal halogenides are effective agents in reactions of siloxane bond cleavage in the poly(dimethylsiloxanes) [33,34]. For the results of such reactions, alkoxysilanes (dimethyldimethoxysilane and trimethylmethoxysilane, see Scheme 1) were formed [34]:…”

Section: Introductionmentioning

confidence: 99%

A New Route for Preparation of Hydrophobic Silica Nanoparticles Using a Mixture of Poly(dimethylsiloxane) and Diethyl Carbonate

et al. 2018

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Abstract:Organosilicon layers chemically anchored on silica surfaces show high carbon content, good thermal and chemical stability and find numerous applications as fillers in polymer systems, thickeners in dispersing media, and as the stationary phases and carriers in chromatography. Methyl-terminated poly(dimethylsiloxanes) (PDMSs) are typically considered to be inert and not suitable for surface modification because of the absence of readily hydrolyzable groups. Therefore, in this paper, we report a new approach for surface modification of silica (SiO 2 ) nanoparticles with poly(dimethylsiloxanes) with different lengths of polymer chains (PDMS-20, PDMS-50, PDMS-100) in the presence of diethyl carbonate (DEC) as initiator of siloxane bond splitting. Infrared spectroscopy (IR), elemental analysis (CHN), transmission electron microscopy (TEM), atomic force microscopy (AFM), rotational viscosity and contact angle of wetting were employed for the characterization of the raw fumed silica and modified silica nanoparticles. Elemental analysis data revealed that the carbon content in the grafted layer is higher than 8 wt % for all modified silicas, but it decreases significantly after sample treatment in polar media for silicas which were modified using neat PDMS. The IR spectroscopy data indicated full involvement of free silanol groups in the chemisorption process at a relatively low temperature (220 • C) for all resulting samples. The contact angle studies confirmed hydrophobic surface properties of the obtained materials. The rheology results illustrated that fumed silica modified with mixtures of PDMS-x/DEC exhibited thixotropic behavior in industrial oil (I-40A), and exhibited a fully reversible nanostructure and shorter structure recovery time than nanosilicas modified with neat PDMS. The obtained results from AFM and TEM analysis revealed that the modification of fumed silica with mixtures of PDMS-20/DEC allows obtaining narrow particle size distribution with uniform dispersity and an average particle size of 15-17 nm. The fumed silica nanoparticles chemically modified with mixtures of PDMS-x/DEC have potential applications such as nanofillers of various polymeric systems, thickeners in dispersing media, and additives in coatings.

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Polysiloxane depolymerization with dimethyl carbonate using alkali metal halide catalysts

Cited by 53 publications

References 16 publications

Performance properties in thick film silicate dielectric layers using molecular modeling

Performance properties in thick film silicate dielectric layers using molecular modeling

DSC study of silicas with immobilized polysiloxane layer of different architecture

A New Route for Preparation of Hydrophobic Silica Nanoparticles Using a Mixture of Poly(dimethylsiloxane) and Diethyl Carbonate

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