Study On The Construction Of Superhydrophobic Coating On Wood Based On Lignin Micro-nanospheres And Their Regulation Mechanism

Lignin micro-nanospheres combine the advantages of lignin and nanomaterials,low cost,rich active sites,high specific surface area,and adjustable size,which make them expected to replace inorganic nanomaterials as potential ideal materials for fabricating wood superhydrophobic coatings.However,there are still some problems such as narrow size control range,difficult precise control,and low production of lignin micro-nanospheres.At the same time,the functional properties and structural regulation mechanisms of the existing lignin micro-nanospheres based superhydrophobic coatings are still unclear.In this study,size-controlled lignin micro-nanospheres were fabricated using enzymolytic lignin as raw material.The evolutionary mechanism of the self-assembly process of lignin molecules was analyzed,and its application performance,functional properties,and structure regulation in wood superhydrophobic coatings were explored.The main research contents and results are follows:(1)At y-valerolactone/water binary system with high solubility of lignin,the aggregation state of lignin molecules was changed by adjusting the process parameters during the self-assembly process,thereby controlling the size of lignin micro-nanospheres.The average diameter of the lignin micro-nanospheres increased with the increase in initial lignin concentration and sonication time,while it decreased with increased water volume.Besides,the average diameter increased first and subsequently decreased with the increased temperature of lignin solution and water.The lignin micro-nanospheres were fabricated in the size range of 30 nm to 3 μm.(2)Nanoscale lignin micro-nanospheres were used as structural materials,after hydrothermal treatment and hydrophobic modification,the lignin micro-nanospheres based superhydrophobic coating was fabricated using epoxy resin and based on the rough structure of wood surface.The contact angle is 164.4° and the sliding angle is 5°.The coating showed great stability in a series of tests,especially good resistance to organic solvent.The coating also exhibited good photothermal effect,which quickly heated up to 122℃ after near infrared irradiation for 10 min.It had excellent application performance in efficient photothermal deicing and sterilization.(3)Lignin microspheres were introduced on the basis of the lignin micro-nanospheres based superhydrophobic system.With the assistance of natural sedimentation,lignin micronanospheres based superhydrophobic coating with dual-scale protective structure were fabricated on various substrates by using their different sedimentation rates.When the size of microspheres was 1μm and the mass ratio of microsphere to nanosphere was 1:0.5,the performance of the superhydrophobic coating reached the highest.The contact angle was as high as 166.1°,and the sliding angle was only 2.8°.The contact angle of the coating was still greater than 150° after abrasion of 320 cm,which had excellent abrasion resistance.