Investigation of hydrolysis and condensation of methyltriethoxysilane in aqueous systems

Kurjata, Jan; Rózga-Wijas, K.; Stańczyk, Włodzimierz A.

doi:10.5155/eurjchem.4.4.343-349.835

Cited by 3 publications

(3 citation statements)

References 31 publications

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“…29 Si NMR spectroscopy of the crude reaction mixture showed a single resonance at −41.5 ppm (Figure S2, Supporting Information). This observed chemical shift is slightly more shielded than in previous reports for MeSi(OH) 3 , 48,49 which we ascribe to the formation of Si−O−K linkages at our high pH of 14; similar results were observed by Suda et al for Si−OH in the presence of alkali (NaOH, KOH, and LiOH) at pH values greater than 13.1. 50 We surmise that the soluble monomer MeSi(OK) 3 is the sole product of the treatment of PMHS with aqueous KOH.…”

Section: Methodssupporting

confidence: 90%

Wettability Reversal of Hydrophobic Pigment Particles Comprising Nanoscale Organosilane Shells: Concentrated Aqueous Dispersions and Corrosion-Resistant Waterborne Coatings

Mishra

Schöttle

Dyk

et al. 2019

ACS Appl. Mater. Interfaces

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We demonstrate the synthesis of polysiloxane-modified inorganic-oxide nanoparticles comprising a TiO2-based pigment (Ti-Pure R-706), which undergo drastic wettability reversal from a hydrophilic wet state to a hydrophobic state upon drying. Furthermore, the dry hydrophobic pigment particles can be reversibly converted back to a hydrophilic form by the application of high shear aqueous milling. Our synthetic approach involves first condensing the cross-linking monomer CH3Si(OH)3 onto the surface of Ti-Pure R-706 at pH 9.5 ± 0.2 in an aqueous suspension. After drying this surface-modified material in the presence of a polyanionic dispersant so as to preserve the primary particle size via dynamic light scattering, it is trimethylsilyl-capped with (CH3)3SiOH, which consumes some residual Si-OH functionalities, and washed to remove all dispersant and excess reagents. Transmission electron microscopy demonstrates a ∼6 nm polysiloxane coating uniformly surrounding the surface of the pigment particle. A 70 wt % (37 vol %) concentrated aqueous slurry of the hydrophobically modified pigment particles prepared in the absence of dispersant exhibits rheological characteristics that are nearly the same as an aqueous dispersion of native unmodified hydrophilic Ti-Pure R-706 comprising an optimal amount of the organic anionic dispersant. It is also possible to synthesize dispersions without the use of an added surfactant and/or dispersant at even higher solid concentrations of up to 75 wt % (43 vol %) in water, conditions at which even the hydrophilic native Ti-Pure R-706 oxide pigment yields a gel-like paste in the absence of a dispersant. Films prepared by drying an aqueous suspension of these pigment particles exhibited a hydrophobic contact angle of ∼125°. When acrylic-based waterborne coatings were prepared comprising these surface-modified Ti Pure R-706 pigments, they showed excellent corrosion protection of a mild steel substrate. These data point to a wettability reversal in which the particles change from hydrophobic to hydrophilic upon high-shear aqueous milling and vice versa upon drying. 29Si CP/MAS NMR spectroscopy highlights the importance of flexibility of the polysiloxane coating for achieving this wettability reversal, a result that emphasizes the importance of surface reconstruction.

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Section: Methodssupporting

confidence: 90%

Wettability Reversal of Hydrophobic Pigment Particles Comprising Nanoscale Organosilane Shells: Concentrated Aqueous Dispersions and Corrosion-Resistant Waterborne Coatings

Mishra

Schöttle

Dyk

et al. 2019

ACS Appl. Mater. Interfaces

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“…The complex equilibrium between species resulting from hydrolysis of trialkoxysilanes, that is, silanols, silanediols, silanetriols, disiloxanes, and linear, cyclic, and branched oligomers, was nicely demonstrated by 1 H and 29 Si NMR and LC/MS . Hydrolysis of MeSi(OEt) 3 in aqueous emulsion and condensation of the various silanols produced thereby were monitored by 29 Si NMR and MS; MeSi(OH) 3 and its dimer (HO) 2 MeSiOSiMe(OH) 2 were found surprisingly long-lived under these conditions, being still detectable after 40 days at ambient temperature along with oligomeric and polymeric condensation products …”

Section: Degradation Of Organosiloxanesmentioning

confidence: 99%

Environmental Chemistry of Organosiloxanes

2014

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“…The most promising agents are those based on alkoxysilanes [ 13 , 17 ]. Their condensation with water results in relatively harmless aliphatic alcohols as side products, and the progress and equilibrium of this reaction can be controlled by pH buffers and the relative concentration of di-, tri-, and mono functional silanes [ 18 ]. In addition to the formulation and use of water repellents themselves, an important issue is the effect of their use on paper recycling processes.…”

Section: Introductionmentioning

confidence: 99%

Siloxane-Starch-Based Hydrophobic Coating for Multiple Recyclable Cellulosic Materials

Ganicz

Rózga-Wijas

2021

Materials

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The results of the application of a new hydrophobization agent based on a triethoxymethylsilane and standard starch aqueous mixture for mass-produced cellulosic materials—printing paper, paperboard, and sack paper—have been evaluated to examine whether such a mixture can be used in industrial practice. The application of this agent on laboratory sheets prepared in a repetitive recycling process was performed to investigate its influence on the formation and properties of the products, as well as the contamination of circulating water. Measurements of the water contact angle, Cobb tests, and water penetration dynamics (PDA) were performed to test the barrier properties of the resulting materials. The effects of the applied coatings and recycling process on the paper’s tensile strength, tear index, roughness, air permeance, and ISO brightness were studied. Studies have proven that this formulation imparts relatively high surface hydrophobicity to all materials tested (contact angles above 100°) and a significant improvement in barrier properties while maintaining good mechanical and optical performance. The agent also does not interfere with the pulping and re-forming processes during recycling and increases circulation water contamination to an acceptable degree. Attenuated total reflectance Fourier-transform infrared (FT-IR) spectra of the paper samples revealed the presence of a polysiloxane network on the surface.

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Investigation of hydrolysis and condensation of methyltriethoxysilane in aqueous systems

Cited by 3 publications

References 31 publications

Wettability Reversal of Hydrophobic Pigment Particles Comprising Nanoscale Organosilane Shells: Concentrated Aqueous Dispersions and Corrosion-Resistant Waterborne Coatings

Wettability Reversal of Hydrophobic Pigment Particles Comprising Nanoscale Organosilane Shells: Concentrated Aqueous Dispersions and Corrosion-Resistant Waterborne Coatings

Environmental Chemistry of Organosiloxanes

Siloxane-Starch-Based Hydrophobic Coating for Multiple Recyclable Cellulosic Materials

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