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Title: Hydrophobic Inorganic Oxide Pigments via Polymethylhydrosiloxane Grafting: Dispersion in Aqueous Solution at Extraordinarily High Solids Concentrations

Abstract

Building on the recent demonstration of aqueous-dispersible hydrophobic pigments that retain their surface hydrophobicity even after drying, we demonstrate the synthesis of surface-modified Ti-Pure R-706 (denoted R706) titanium dioxide-based pigments, consisting of a thin (one to three monolayers) grafted polymethylhydrosiloxane (PMHS) coating, which (i) are hydrophobic in the dry state according to capillary rise and dynamic vapor sorption measurements and (ii) form stable aqueous dispersions at solid contents exceeding 75 wt % (43 vol %), without added dispersant, displaying similar rheology to R706 native oxide pigments at 70 wt % (37 vol %) consisting of an optimal amount of conventional polyanionic dispersant (0.3 wt % on pigment basis). Additionally, the surface-modified pigments have been characterized via 29Si and 13C cross-polarization/magic angle spinning solid-state NMR spectroscopy; infrared spectroscopy; thermogravimetric and elemental analyses; and ζ potential measurements. On the basis of these data, the stability of the surface-modified PMHS-R706 aqueous dispersions is attributed to steric effects, as a result of grafted PMHS strands on the R706 surface, and depends on the chaotropic nature of the base used during PMHS condensation to the pigment/polysiloxane interface. The lack of water wettability of the surface-modified oxide particles in their dry state translates to improved water-barriermore » properties in coatings produced with these surface-modified pigment particles. Finally, the synthetic approach appears general as demonstrated by its application to various inorganic-oxide pigment particles.« less

Authors:
 [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [2]; ORCiD logo [2];  [3];  [3];  [3];  [3];  [1]; ORCiD logo [1]
  1. Univ. of California, Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. The Dow Chemical Company, Midland, MI (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1571112
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 34; Journal Issue: 39; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Guo, Yijun, Mishra, Manish K., Wang, Futianyi, Jankolovits, Joseph, Kusoglu, Ahmet, Weber, Adam Z., Van Dyk, Ant, Beshah, Kebede, Bohling, James C., Roper III, John A., Radke, Clayton J., and Katz, Alexander. Hydrophobic Inorganic Oxide Pigments via Polymethylhydrosiloxane Grafting: Dispersion in Aqueous Solution at Extraordinarily High Solids Concentrations. United States: N. p., 2018. Web. doi:10.1021/acs.langmuir.8b01898.
Guo, Yijun, Mishra, Manish K., Wang, Futianyi, Jankolovits, Joseph, Kusoglu, Ahmet, Weber, Adam Z., Van Dyk, Ant, Beshah, Kebede, Bohling, James C., Roper III, John A., Radke, Clayton J., & Katz, Alexander. Hydrophobic Inorganic Oxide Pigments via Polymethylhydrosiloxane Grafting: Dispersion in Aqueous Solution at Extraordinarily High Solids Concentrations. United States. doi:10.1021/acs.langmuir.8b01898.
Guo, Yijun, Mishra, Manish K., Wang, Futianyi, Jankolovits, Joseph, Kusoglu, Ahmet, Weber, Adam Z., Van Dyk, Ant, Beshah, Kebede, Bohling, James C., Roper III, John A., Radke, Clayton J., and Katz, Alexander. Tue . "Hydrophobic Inorganic Oxide Pigments via Polymethylhydrosiloxane Grafting: Dispersion in Aqueous Solution at Extraordinarily High Solids Concentrations". United States. doi:10.1021/acs.langmuir.8b01898. https://www.osti.gov/servlets/purl/1571112.
@article{osti_1571112,
title = {Hydrophobic Inorganic Oxide Pigments via Polymethylhydrosiloxane Grafting: Dispersion in Aqueous Solution at Extraordinarily High Solids Concentrations},
author = {Guo, Yijun and Mishra, Manish K. and Wang, Futianyi and Jankolovits, Joseph and Kusoglu, Ahmet and Weber, Adam Z. and Van Dyk, Ant and Beshah, Kebede and Bohling, James C. and Roper III, John A. and Radke, Clayton J. and Katz, Alexander},
abstractNote = {Building on the recent demonstration of aqueous-dispersible hydrophobic pigments that retain their surface hydrophobicity even after drying, we demonstrate the synthesis of surface-modified Ti-Pure R-706 (denoted R706) titanium dioxide-based pigments, consisting of a thin (one to three monolayers) grafted polymethylhydrosiloxane (PMHS) coating, which (i) are hydrophobic in the dry state according to capillary rise and dynamic vapor sorption measurements and (ii) form stable aqueous dispersions at solid contents exceeding 75 wt % (43 vol %), without added dispersant, displaying similar rheology to R706 native oxide pigments at 70 wt % (37 vol %) consisting of an optimal amount of conventional polyanionic dispersant (0.3 wt % on pigment basis). Additionally, the surface-modified pigments have been characterized via 29Si and 13C cross-polarization/magic angle spinning solid-state NMR spectroscopy; infrared spectroscopy; thermogravimetric and elemental analyses; and ζ potential measurements. On the basis of these data, the stability of the surface-modified PMHS-R706 aqueous dispersions is attributed to steric effects, as a result of grafted PMHS strands on the R706 surface, and depends on the chaotropic nature of the base used during PMHS condensation to the pigment/polysiloxane interface. The lack of water wettability of the surface-modified oxide particles in their dry state translates to improved water-barrier properties in coatings produced with these surface-modified pigment particles. Finally, the synthetic approach appears general as demonstrated by its application to various inorganic-oxide pigment particles.},
doi = {10.1021/acs.langmuir.8b01898},
journal = {Langmuir},
number = 39,
volume = 34,
place = {United States},
year = {2018},
month = {8}
}

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