| Cellulose,hemicellulose and lignin together constitute the main components of wood cell wall.However,there are a large number of hydroxyl groups in it,which makes wood have strong water absorption and hygroscopicity.When the external temperature and humidity change,it will absorb or resolve moisture,resulting in a large change in wood size,that is,size instability.Ultimately,quality issues such as dry shrinkage,moisture expansion,and deformatio n cracking occur in wood,which also have varying degrees of impact on the physical and mechanical properties of the wood.Hydrophobic treatment of wood plays a crucial role in solving the problem of water absorption or moisture absorption.In this study,we prepared stable ZIF-8nanoparticles and paraffin/ZIF-8 mixed lotion,combined with the low surface energy substance hexadecyl trimethoxysilane(HDTMS)to modify,and prepared superhydrophobic coatings on impregnated wood or its coating materials.By regulating the microstructure and chemical composition of the wood surface,while constructing a micro/nano multi-scale rough structure to make it hydrophobic,the wood surface has good wear resistance,self-cleaning,transparency,and self-healing performance.The main research content and resu lts of the paper are as follows :(1)Paraffin,as a commonly used waterproofing agent,was used to impregnate wood with a mixture of ZIF-8 nanoparticles and paraffin.The purity of the prepared ZIF-8 nanoparticles was analyzed,the stability of the mixed lotion system was tested by room temperature placement method,the microstructure of ZIF-8 crystal and the mixed lotion under SEM and TEM was observed,and the hydrophobic property of the film was tested and analyzed.Th e results showed that the ZIF-8 nanoparticles prepared using methanol as a solvent had good purity and a size of about 100nm;The compatibility of paraffin/ZIF-8 blends in lotion state was good,and the storage stability was Grade 1.Compared with the wood impregnated with pure paraffin lotion,the surface contact angle of the wood impregnated with paraffin/ZIF-8 blend was higher,and the purpose of improving the hydrophobic p roperty of the wood was achieved.(2)The wood was impregnated with ZIF-8 and paraffin lotion,and then the wood was impregnated with HDTMS,a low surface energy material.Observing the effect of HDTMS concentration on the morphology of treated materials through SEM and EDS.Test the effect of HDTMS concentration and ZIF-8 concentration on the water absorption performance of treated materials;FTIR chemical composition testing and analysis of hydrophobic membranes,and AFM quantitative characterization of wood surface roughness.The results showed that when the concentration of HDTMS was 0.1%,the nanoparticle distribution on the wood surface treated with 40wt% ZIF-8 mixed lotion was the most uniform;When the concentration of ZIF-8 is 40wt% and the concentration of HDTMS was 0.15%,the contact angle value was the highest.HDTMS secondary modification not only reduces the free energy of the wood surface,modifies the aggregation state of nanoparticles,changes the rough structure of the membrane,but also acts as an adhesive for ZIF-8 particles,increasing the bonding strength between particles and wood.After 10 wear tests,the contact angle decreased to 91% before friction,but still maintained high hydrophobicity.The water absorption test showed that the water absorption of the samples decreased significantl y after being treated with mixed lotion of different proportions.(3)In order to simplify the preparation process of superhydrophobic coating,the synthetic ZIF-8/paraffin lotion was mixed with HDTMS and directly brushed on the surface of varnished wood t o prepare a hydrophobic film.The microstructure,chemical composition,and hydrophobicity of the coating were characterized by SEM,AFM,FTIR,and contact angle measuring instruments,as well as the transparency of the hydrophobic film was detected by UV/ visible spectrophotometer.The results showed that the addition ratio of ZIF-8 and HDTMS in the mixed lotion affected the microstructure of the hydrophobic film.When the ratio was 5:1,the nano particles were evenly dispersed on the varnish interface and formed particle clusters of different sizes,which further transformed the treated material from hydrophobic state to super hydrophobic state.The light transmittance of the blank glass slide is about 90%.After brushing the varnish coating,the light tran smittance is almost unchanged.After continuing to brush the mixed lotion,the light transmittance decreases to 80%.After 10 times of coating wear,although the contact angle has decreased,it still exceeds 150 °,and the transmittance was still high.The one-step superhydrophobic wear resistance was good.(4)Polydimethylsiloxane(PDMS)was used as the pre prepared layer on the wood surface,and ZIF-8/paraffin lotion was used to build the surface rough structure,and the superhydrophobic coating was co constructed.By utilizing the thermal response characteristics of wood,the modifiers stored in the porous structure of wood can promote the repair of coatings after thermal induction reactions.Observing the micro morphology of superhydrophobic films,tes ting their hydrophobicity,mechanical wear resistance,and self-healing properties,and testing the UV shielding performance of superhydrophobic coatings.The results indicate that the constructed micro/nano rough structure endows the wood with good hydrophobicity and wear resistance.After severe mechanical wear,the hydrophobic film undergoes heating treatment,and the PDMS and its coated nanoparticles on the wood surface migrate to the surface.This not only supplements the low surface energy substances on the surface,but also improves the roughness,giving the hydrophobic film a certain degree of self-healing ability.The UV absorption test results indicate that the superhydrophobic coating can achieve UV shielding effect by reflecting and scattering UV light,and still maintains good transparency after 16 8hours of UV irradiation at 60 ℃. |
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