A method for constructing a superhydrophobic, self-cleaning, highly weather-resistant composite coating on bamboo scrimber using wood wax oil and zeolitic imidazolate Framework-8

Bamboo scrimber (BS) as an engineering material has been widely used in outdoor areas, in order to improve the protective properties of bamboo scrimber, this study prepared a new composite coating. Wood wax oil (WO) and Zeolitic Imidazolate Framework-8 (ZIF-8) nanoparticles were prepared separately, and ZIF-8 nanoparticles were modified with low surface energy perfluorooctyltriethoxysilane (POTS). ZIF-8/POTS nanoparticles were constructed on the surface of bamboo scrimber to form ZIF-8/POTS/WO/BS composite coatings via the mediating effect of wood wax oil. The composite coatings were superhydrophobic, with a water contact angle of 161.4°. After aging tests, the contact angle of the composite coatings decreased by only 6.51 %, indicating that they remained superhydrophobic. Compared with uncoated substrates, after anti-mildew and preservative treatment tests, the bamboo scrimber coated with ZIF-8/POTS/WO/BS showed an improvement in its discoloration level from grade 4 to grade 1 and an infection level improvement from grade 3 to grade 0. The composite coatings had a nanoscale surface roughness with a surface energy of 2.94 mJ/m 2 . The coatings also exhibited self-cleaning performance, with a dust removal efficiency of 90.91 %. The air layer created on the surface of the composite coating made it difficult for water and microorganisms to directly contact the surface of the coatings. Furthermore, The Zn 2+ ions and 2-methylimidazole released by ZIF-8 disrupted the ionic balance in the surrounding environment, achieving a dual synergistic antifungal effect, which inhibited microbial growth and reproduction on the surface of the coatings, thus providing greater outdoor protection. This work pioneered the use of MOFs and wood wax oil to construct superhydrophobic, self-cleaning, and weather-resistant composite coatings on bamboo scrimber. This coating may enable bamboo scrimber to be used in outdoor building structures, highway guardrails, and bridge components, especially in harsh and wet outdoor environments.