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Rapid curing of polysilazane coatings at room temperature via chloride-catalyzed hydrolysis/condensation reactions

Zhan, Ying ; Li, Wei ; Grottenmüller, Ralf ; Minnert, Christian ; Krasemann, Thomas ; Wen, Qingbo ; Riedel, Ralf (2022):
Rapid curing of polysilazane coatings at room temperature via chloride-catalyzed hydrolysis/condensation reactions.
In: Progress in Organic Coatings, 167, Elsevier, ISSN 03009440, e-ISSN 1873331X,
DOI: 10.1016/j.porgcoat.2022.106872,
[Article]

Abstract

Moisture curing of polysilazane coatings at room temperature is of advantage to industrial applications, though it often takes a longer time than the other curing methods. To tackle this problem, tetrabutylammonium chloride (TBAC) is applied in this work as an efficient catalyst for the hydrolysis and condensation reactions of polymethyl (hydro)/polydimethylsilazane coatings under ambient conditions. In the suggested catalytic mechanism, the Si-H group is nucleophilically attacked by chloride ions to form a transient Si-Cl group, which is then nucleophilically substituted by a hydroxyl group from the moisture environment. It is found that by adding TBAC in the polysilazane coating, 1.6 times more of the reactive groups (Si-H, Si-NH) are consumed during the curing process in a shorter time (the dry-to-touch time for the uncatalyzed and the TBAC-catalyzed polysilazane coatings are ca. 19 h and 1 h, respectively), while 2 times more of the Si-O-Si groups are formed. Owing to the significantly enhanced crosslinking rate and degree, the coating quality and the mechanical properties are greatly improved. The hardness and the elastic modulus of the coating are increased by a factor of two and four, respectively.

Item Type: Article
Erschienen: 2022
Creators: Zhan, Ying ; Li, Wei ; Grottenmüller, Ralf ; Minnert, Christian ; Krasemann, Thomas ; Wen, Qingbo ; Riedel, Ralf
Title: Rapid curing of polysilazane coatings at room temperature via chloride-catalyzed hydrolysis/condensation reactions
Language: English
Abstract:

Moisture curing of polysilazane coatings at room temperature is of advantage to industrial applications, though it often takes a longer time than the other curing methods. To tackle this problem, tetrabutylammonium chloride (TBAC) is applied in this work as an efficient catalyst for the hydrolysis and condensation reactions of polymethyl (hydro)/polydimethylsilazane coatings under ambient conditions. In the suggested catalytic mechanism, the Si-H group is nucleophilically attacked by chloride ions to form a transient Si-Cl group, which is then nucleophilically substituted by a hydroxyl group from the moisture environment. It is found that by adding TBAC in the polysilazane coating, 1.6 times more of the reactive groups (Si-H, Si-NH) are consumed during the curing process in a shorter time (the dry-to-touch time for the uncatalyzed and the TBAC-catalyzed polysilazane coatings are ca. 19 h and 1 h, respectively), while 2 times more of the Si-O-Si groups are formed. Owing to the significantly enhanced crosslinking rate and degree, the coating quality and the mechanical properties are greatly improved. The hardness and the elastic modulus of the coating are increased by a factor of two and four, respectively.

Journal or Publication Title: Progress in Organic Coatings
Volume of the journal: 167
Publisher: Elsevier
Uncontrolled Keywords: Polysilazane coatings; Tetrabutylammonium chloride; Catalysis; Hydrolysis; condensation; Nanoindentation POLYMER-DERIVED CERAMICS; ELASTIC-MODULUS; THIN-FILMS; PART I; PERHYDROPOLYSILAZANE; SILICA; CONVERSION; INDENTATION; PRECURSORS; ATMOSPHERE
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science > Physical Metallurgy
Date Deposited: 10 Jun 2022 06:53
DOI: 10.1016/j.porgcoat.2022.106872
Additional Information:

Artikel-ID: 106872

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