Superhydrophobic Covalent Organic Frameworks Prepared via Pore Surface Modifications for Functional Coatings under Harsh Conditions

Na Han; Zongxuan Zhang; Hongkun Gao; Yongqiang Qian; Linli Tan; Chao Yang; Haoran Zhang; Zhenyu Cui; Wei Li; Xingxiang Zhang

doi:10.1021/acsami.9b17319

Superhydrophobic Covalent Organic Frameworks Prepared via Pore Surface Modifications for Functional Coatings under Harsh Conditions

ACS Appl Mater Interfaces. 2020 Jan 15;12(2):2926-2934. doi: 10.1021/acsami.9b17319. Epub 2020 Jan 6.

Authors

Na Han^{1

2

3}, Zongxuan Zhang^{1

2}, Hongkun Gao^{1

2}, Yongqiang Qian^{1

2}, Linli Tan^{1

2}, Chao Yang^{1

2}, Haoran Zhang^{1

2}, Zhenyu Cui^{1

2}, Wei Li^{1

2}, Xingxiang Zhang^{1

2}

Affiliations

¹ State Key Laboratory of Separation Membranes and Membrane Processes , Tiangong University , Tianjin 300387 , China.
² School of Materials Science and Engineering , Tiangong University , Tianjin 300387 , China.
³ Department of Textile Engineering, Chemistry & Science, College of Textiles , North Carolina State University , Raleigh , North Carolina 27606 , United States.

PMID: 31750647
DOI: 10.1021/acsami.9b17319

Abstract

Covalent organic frameworks (COFs) have been widely used in catalysis, energy storage, environmental protection, and separation. However, they require a long assembly period (∼3 days) and complex synthesis conditions; differences in water resistance have restricted their overall versatility. In this paper, the preparation of COF-DhaTab was optimized, and this process can be easily performed in air. Thus, it is feasible for the scale-up of COF-DhaTab in the near future. The superhydrophobic properties of COF-DhaTab (water contact angle, >150°) can be created by regulating the wettability of COF-DhaTab by grafting fluoride. When the grafting degree of fluoride increased to 4.32%, the water contact angle of COFs increased from 0° to more than 150°. The grafted COFs are termed COF-DhaTab fluoride (COF-DTF). The chemically modified COF-DhaTab maintains its original porosity and crystallinity. The superhydrophobic COF-DTF can be applied to various substrates, for example, foam, fabric, and glass. These all exhibit outstanding water repellency, self-healing, and excellent self-cleaning. Importantly, the coating maintains its original superhydrophobicity even under extremely acidic/basic conditions (pH = 1-14) and toward boiling water (100 °C). Furthermore, COF-DTF displays long-term stability and is easily scaled. It is a promising and practical candidate for hydrophobic modifications to various substrates.

Keywords: covalent organic frameworks; melamine foam; pore surface modification; superhydrophobicity.