Preparation Of Superhydrophobic Structure Of Surface Acylated Cellulose And Its Application On Wood Surface

Superhydrophobic materials have great application potential in self-cleaning,antifouling,drag reduction and other aspects,but most of the superhydrophobic materials are prepared from fluorinated compounds or silane,which have certain harm to the environment.In addition,the complex preparation process of superhydrophobic coating also limits its application,so the development of superhydrophobic materials based on natural materials through simple methods has become a research focus.Cellulose has many advantages such as abundant reserves,renewable,biodegradable and easy functionalization modification,and has potential applications in the field of environment-friendly superhydrophobic materials.Therefore,in this study,the hydrophobic functionalized modification of microcrystalline cellulose was carried out,and the superhydrophobic coating was prepared on wood surface by simple self-assembly and spraying method.The main research contents and results are as follows:（1）The 10-undecenyl cellulose was synthesized by heterogeneous esterification reaction of microcrystalline cellulose and 10-undecenyl chloride.It was characterized by FTIR,¹³C NMR,DLS and TEM.The results showed that the product existed in a spherical state with an average diameter of 218 nm and and a degree of substitution of 1.9,so it was named UCE_1.9.UCE_1.9 nanoparticles were prepared as micron particles(UCE_1.9MPs)using self-assembly,and the UCE_1.9MPs were sprayed onto the wood surface to produce superhydrophobic wood with micro-nano structures.The superhydrophobic surfaces prepared with different concentrations achieved contact angle of 170°and a sliding angle of 4°,with good superhydrophobicity and excellent thermal stability.The contact and sliding angles did not change significantly after heating at 100°C and 150°C.The surface also has self-cleaning properties and acid-base stability at p H 2-13.（2）Fully substituted cellulose（UCE₃）was synthesized by regulating the amount of 10-undecanoyl chloride and reaction temperature in the heterogeneous esterification reaction.The UCE₃ solution was prepared as UCE₃ nanoparticles（UCE₃NPs）by self-assembly.UCE_1.9MPs and UCE₃NPs were mixed with different mass fractions and sprayed onto the wood surface to construct superhydrophobic wood with micro-nano structures,and the surface was heated to form a carbon-carbon double bond cross-linked network structure.The results show that the prepared surfaces have excellent superhydrophobicity and thermal stability,with contact angles above 153°and sliding angles below 8°before and after heating,and mechanical stability compared to the surfaces without UCE₃NPs,with contact angles of 138°and 145°after 100cycles of sandpaper abrasion and tape peeling tests.（3）Microcrystalline cellulose was hydrolyzed into cellulose nanocrystalline（CNC）,which was then reacted with stearyl chloride to form stearyl cellulose nanocrystalline（SCNC）.In order to improve the adhesion between particles,SCNC and polystyrene with different mass fractions were mixed for self-assembly and sprayed onto the wood surface to obtain SCNC-PS superhydrophobic wood.SCNC-PS wood superhydrophobic surface was tested for superhydrophobicity,thermal stability and mechanical stability.The results showed that the wood superhydrophobic surface has excellent superhydrophobicity with contact angle above165°and sliding angle less than 5°,and can withstand the impact of droplets with a maximum weber of 345.The contact and sliding angles remained almost unchanged after heating,and the superhydrophobic properties were maintained.The surface with polystyrene added showed a significant improvement in mechanical stability compared to the non-added surface,with the contact angle increasing from 106°to 147°after 100 cycles of sandpaper wear testing.In this study,the hydrophobic cellulose ester of different scales was used as the basic building unit,and the supramolecular self-assembly method was used to achieve efficient and stable construction of cellulose based superhydrophobic structure on wood surface.The prepared surface not only has excellent superhydrophobic properties,but also has thermal stability,self-cleaning and environmental friendliness.This study realizes the green modification concept of modifying wood itself with cellulose,the main macromolecular component of wood,promotes the research and development of natural polymer-based materials for superhydrophobic biomimetic modification of wood,and enriches the theoretical system of superhydrophobic biomimetic modification of wood.