桉木表面构建层状双氢氧化物仿紫光檀颜色

Construction and characterization of layered double hydroxides on eucalyptus wood surface to imitate violet sandalwood color

【目的】针对人工林速生桉木材色较浅、表面色调单一的问题,以层状双金属氢氧化物(LDHs)对其进行材色调控,仿制名贵木材紫光檀的黑棕色效果。【方法】将与木材高度亲和的钴基金属有机框架(Co-MOF)作为模板和前驱体,利用MnCl_(2)在木材表面发生水解反应,在桉木单板表面制备钴锰层状双金属氢氧化物(CoMn-LDH);探究桉木单板分别在0.016、0.032、0.064 mol/L MnCl_(2)溶液和20、40、60、80℃条件下表面颜色的变化规律;并通过扫描电镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和红外光谱(FT-IR)分析,探究LDHs与桉木单板表面的结合机理;通过接触角和耐光老化测试评估改色木材的耐水性和耐光老化性。【结果】(1)在40℃下,利用0.032 mol/L MnCl_(2)溶液制得的钴锰双氢氧化物涂层桉木单板实现了紫光檀颜色效果,两者的色度值和紫外光谱均相近。(2)MnCl_(2)水解诱导Co-MOF和木材的OH−交换形成金属氢氧化物,生成CoMn-LDH;SEM显示CoMn-LDH具有微纳米复合结构,XRD和XPS分析表明钴和锰分别以Co^(2+)和Mn^(2+)的形式存在,CoMn-LDH为典型的钴锰双氢氧化物;其红外光谱呈金属–羟基振动模式。(3)调色木材的接触角由36.2°增大至49.5°;光照120 h后色差在3~6范围内,属于中质量分辨率下可见色差;表明制备的钴锰双氢氧化物涂层桉木单板表面疏水能力和耐光老化性能均得到提升。【结论】本研究所用调色处理条件温和,能有效改善桉木颜色,提高产品装饰效果和附加值,促进人工林木材的高效利用。

[Objective]To address the issue of light color and uniform surface tone in fast-growing eucalyptus wood,layered double hydroxides(LDHs)were utilized to control the wood’s color and replicate the dark brown color of the valuable wood species,purple sandalwood(Dalbergia melanoxylon).[Method]Co-based metal organic framework(Co-MOF)was employed as templates and precursors due to their strong affinity for wood.By catalyzing the hydrolysis reaction of MnCl_(2)on the wood surface,CoMnlayered double hydroxide(CoMn-LDH)was synthesized on eucalyptus veneers.We investigated the color variations of eucalyptus veneers subjected to three concentrations of MnCl_(2)solution(0.016,0.032,0.064 mol/L)and temperature of 20,40,60 and 80℃.The interaction mechanism of LDHs with eucalyptus veneer surface was analyzed using scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and Fourier transform infrared spectroscopy(FT-IR).Assessments of water resistance and light aging resistance of the color-modified wood were conducted through contact angle and light aging tests.[Result](1)At 40℃,CoMn-LDH-wood produced using 0.032 mol/L MnCl_(2)solution successfully replicated the color effect of Dalbergia melanoxylon,exhibiting similar chromaticity values and UV spectra.(2)The hydrolysis of MnCl_(2)induced an exchange process between Co-MOF and OH−,leading to the formation of metal hydroxides and the creation of CoMn-LDH.Characteristic techniques such as SEM,XRD,XPS,and FT-IR confirmed the composite structure of CoMn-LDH,with cobalt and manganese existing in Co2+and Mn2+forms,representing characteristic features of CoMn double hydroxides.The colormodified wood showed an increase in static water contact angle from 36.2°to 49.5°,and after 120 h of light exposure,the color difference fell within the range of 3 to 6,indicating a perceptible color shift at a moderate resolution.These results suggested that the prepared CoMn-LDH-wood displayed enhanced surface hydrophobicity and light aging resistance.[Conclusion]The mild color adjustment treatment conditions applied in this study effectively enhance the color of eucalyptus wood,augmenting its aesthetic appeal and commercial value,thereby fostering the sustainable utilization of wood resources from artificial forests.