Fabrication and Functionalization of Wood Nanomaterial Composites via Magnetron Sputtering

Author:Bao Wen Hui

Supervisor:li jian


Degree Year:2019





Wood material is a renewable traditional material with light weight,high strength-to-weight ratio,good elasticity,impact resistance and easy processing.With the increase of population,depletion of resources,destruction of ecological environment and other factors,high-quality timber resources are gradually reduced,and costs are greatly increased.Low-quality plantations can alleviate the shortage of resources,but fast-growing materials have the disadvantages of loose material,low density,poor dimensional stability,and no corrosion resistance.In order to achieve the purpose of inferior use,functional improvement is an important means to achieve efficient use of wood materials.Magnetron sputtering is a coating technology widely used in various fields of industrial production.The main research contents and results of this paper:1)Master the operation method of magnetron sputtering equipment.The results show:(1)The five metal films(Cu,Ni,Fe,Ti,Zn)prepared on the surface of bamboo exhibited an island-like growth mode,and the film layer was uneven and had obvious cracks.The Zn film sputtered the largest particle size.(2)The Fe film exists in an amorphous structure,and Cu,Ni,Ti,and Zn exhibit a polycrystalline phase structure and exhibit a certain preferred orientation.As the sputtering power increases,the activity of the neutral metal particles increases,and it is easier to diffuse on the substrate to form dense grains.(3)Although magnetron sputtering is a physical vapor deposition,the sputtering process also belongs to a weak plasma environment,will activate the surface functional group-CH of bamboo,it is more susceptible to oxidation in the atmosphere.(4)Atomic force microscopy of metal film roughness range of 17.6-40.8nm,the roughness of the non-contact 3D morphology scan test is 8.64-12.71 μm,and the contact angle surface of the metal film is lower than the pristine material.2)Using micro-contact printing,the PDMS with FeCl3 solution is stamped on the Cu film on the bamboo surface.Transfer replica of natural lotus leaf mastoid structure,exploring the effects of different concentrations of etching solution on crystal morphology and crystallization characteristics.The results show:(1)Different concentrations of FeCl3 solution have significant effects on the etched morphology,appropriate conditions for the structure of lotus leaf papillae with complete size and uniform distribution on the surface of bamboo Cu film:FeCl3 solution concentration 30%,modified by low surface energy materials with a contact angle of 152°,the original bamboo is only a contact angle of 44°.(2)After 100 times of sand abrasion,strong magnetic stirring in water at 30~90℃,the contact angle does not significantly change,is 151°,after 6 months of environmental test,the contact angle is 147°.(3)The micro-contact printing method is also applied to the micro-nano structure transfer replica of the rose petal surface,and the actual transfer effect is not obvious.This is mainly due to the large density of the surface micro-nano structure,the longitudinal depth is not obvious,and the precise etching cannot be realized.Therefore,the process parameters such as imprint pressure,time,and PDMS thickness need to be further explored.3)Alkaline mixed solution of NaOH and(NH4)2S2O8,Nanostructured nanomaterials such asnanoneedle Cu(OH)2 and nanoflower CuO were grown on the surface of a bamboo sample sputtered with a 30μm thickness of Cu film.The results show:(1)After modification with perfluorodecanoic acid,the contact angle test showed that the morphology had a significant effect on the wettability.In order to achieve super-amphiphobic,the suitable conditions for the growth of nanomaterials on the surface of bamboo:2.5M NaOH and 0.12M(NH4)2S2O8,reaction time 10 minutes.Obtaining a composite structure of nano-petals grown on the tip of a nanoneedle,the contact angle of water reaches 154°and oil is 152°.(2)Analyze and explain the growth mechanism of inorganic nanomaterials:polycrystalline Cu(OH)2 nanowires are evolved into directional Cu(OH)2 as a sequence,and then single crystal Cu(OH)2 is reconstituted into single crystal CuO.For the sequence,CuO is verified as a sequence and then sequentially passes through a one-dimensional CuO nanobelt,and finally a two-dimensional CuO nanosheet structure is formed.The one-dimensional to two-dimensional process is caused by the thermodynamics caused by the reduction in surface energy and sequence.The reason for this is mainly the difference in surface energy between crystal planes.(3)The three mechanical stability experiments of sand abrasion,sandpaper abrasion and finger pressure method show that the sample can resist the finger pressure method and 100 sand abrasion,and still exhibit super-amphiphobic state.However,it can not resist the abrasion of sandpaper,that is,the sample slides by a distance of 9cm through 100g weight sandpaper,and its surface exhibits hydrophilic and oleophilic wetting characteristics to the contact angle,which is mainly due to the peeling of the special concave corner structure on the sample surface.(4)After the abrasion,the sample is re-oxidized by alkali to obtain the composite structure of the nano-petals grown at the top of the nanoneedle.Design a series circuit,the universal meter measures the resistance of the super-amphiphobic sample to 15.2Ω.4)In the cross-section of wood,the Cu film was sputtered on the surface of the cell wall and cell cavity,and the effect of sputtering thickness on crystal morphology,surface roughness and wettability was investigated.The results show:(1)The thickness of the sputtering is between 30-150nm,and different morphological and uniform Cu particles will form on the surface of the wood;the surface morphology will gradually change from tiny particles to micron-sized sheet structure until the final adhesion of Cu film is formed.The best process parameters for obtaining superhydrophobic properties in the cross section of wood:Sputtering 50nm thickness of Cu film,that is,a vertical nanosheet-like structure with uniform surface growth,the combination of the sheet structure and the wood channel can retain more air,increase the surface roughness,and the contact angle after modification with perfluoroantimonic acid is 154°.(2)Using this rough structure,a mixture of methyl mercaptan and a carboxy thiol is modified to prepare a pH-responsive wetting surface for the acid droplets and the alkali droplets.The effect of the concentration of methyl mercaptan and carboxy thiol mixed solution on the wettability is discussed.The optimum process parameters:when the carboxy thiol accounts for 60%of the mixed thiol ratio,the difference in contact angle between the surface of the sample and the droplet of acid and alkali is the most.Obviously,this is mainly due to the deprotonation of acid-base droplets on the surface.5)Wood-based nanocomposites with different thickness Ti films were prepared and their mechanical properties were analyzed in depth.The results show that:(1)The modulus of the pristine material is 33 MPa,and the wood with 5 μm thickness of Ti film is sputtered to have a modulus of elasticity of 41.5 MPa.Analyze and explain the rigid mechanism:the wood substrate belongs to a cellulose polycrystalline structure.When the sputtered Ti atoms are deposited on the wood substrate,a coherent crystal plane is formed at the grain boundary.Since the boundary of the coherent crystal plane is very low,Therefore,no more boundaries are formed,resulting in large and irregular grains,easy formation of large atomic clusters,formation of dislocation sources,formation of dislocations when the sample is subjected to external forces,and dislocation accumulation and entanglement,which will restrict the next dislocation.Hardening effect.(2)The wood sputtered with the metal film is used as the surface material of the ping-pong floor,which is tested by professional athletes.The bottom plate shows good results in terms of rebound efficiency,rebound distance and feel.6)The wood was immersed in PDMS ethyl acetate solution with different solution concentrations,and different thickness Cu films were sputtered to analyze and characterize the prepared composites.The results show that the filling and adhesion of PDMS will reduce the surface roughness of the wood.The surface roughness of the wood is reduced from 7.9μm to 40nm by 3D non-contact contour scanning test.On the surface of the wood to which PDMS was adhered,a Cu film of different thicknesses of 100 nm to 5 μm was prepared by DC magnetron sputtering.When a 5 μm thick Cu film was sputtered on the surface of a PDMS having a roughness of 40 nm,the resistance was at least 0.5Ω.7)On the wood substrate CuO,Cu2O,WO3,and MoO3 films were prepared by RF sputtering.From the XRD results,the WO3 and MoO3 films are all amorphous,which is due to the large lattice mismatch between the film and the wood substrate.The dense film layer needs to be post-annealed.In the anaerobic state,different thicknesses of CuO films were sputtered.The results show that the films with different thicknesses exhibit mixed crystal state.When the thickness of the sputtered film is 100 nm,CuO preferential growth and Cu doping mixed crystal phase structure are exhibited,which is mainly due to CuO.The anion-cation sputtering yield of the ceramic target is different,which causes the target O to be absent,forming a sputtering environment rich in Cu-poor O.For the preparation of Cu2O film,different flow rates of Ar and O2 were carried out.The results show that when lOsccmAr,1~2sccm O2 is introduced,a single-phase Cu2O structure can be prepared.When the oxygen flow rate is 3~4sccm O2,two phases of CuO and Cu2O are formed,structure.