Flexible transparent wood enabled by epoxy resin and ethylene glycol diglycidyl ether

Transparent wood has potential application in intelligent building,solar cell,electronics,and other advanced materials,while its single functionability hinders its further development.Flexible transparent wood(FTW)was prepared by alkaline pretreatment and bleaching treat-ment of paulownia wood followed by impregnation of epoxy resin and ethylene glycol diglycidyl ether(EDGE).The eff ect of delignifi cation degree on the optical and mechani-cal properties of FTW was studied,and the infl uence of the epoxy/EDGE ratio on the fl exibility and mechanical proper-ties of FTW was also investigated.The results showed that higher delignifi cation degree resulted in higher transmit-tance of FTW.More EDGE addition led to better fl exibility of FTW,while overmuch addition of EDGE will reduce the mechanical properties.The optimal FTW sample resulted in a high transmittance of 89%and an ultrahigh haze value of 97%with outstanding fl exibility and excellent mechanical properties.The investigation of FTW broadens the research fi eld of transparent wood,and provides great possibility for its application in fl exible wearable devices and fl exible materials.

Transparent Photochromic Wood Composites Incorporating AgBr Nanoparticles for UV-shielding Applications

Transparent wood(TW)is a wood-based biomaterial with several advantages,such as high optical transmittance,low thermal conductivity,and tunable haze.TW is functionalized according to its transparency to broaden its applications in different fields.Several studies have examined wood functionalization in recent years;however,few studies have reported photochromic TW(PTW)for ultraviolet(UV)-shielding window applications.Herein,PTW was obtained by infiltrating the delignified wood template with photochromic silver bromide(AgBr)nanoparticles and a pre-polymerized methyl methacrylate(MMA)mixture solution.The obtained PTW can adjust the luminous flux on change in the color in the visible light region.The photochromic properties were examined,and the optical properties of the composites were characterized using UV-Vis spectrophotometry.Light transmittance of PTW was up to 86.5%at 800 nm before UV irradiation,and it decreased to 70.1%at 800 nm after UV irradiation,as the wood color changed from colorless to dark purple under UV irradiation.Thus,this work not only achieves high-value utilization of wood,but also produces a new material that can be used in varied fields,such as UV-shielding,energy saving,and smart building.

Preparation and properties of hydrophobic and transparent wood

Natural wood(NW)was treated with sodium chlorite to obtain delignified wood(DW)in this study,then epoxy was impregnated to get transparent wood(TW),and finally the TW was coated with perfluorodecyltriethoxysilane(FAS)to acquire hydrophobic and transparent wood(HTW).The hydroxyl group generated by the hydrolysis of the FAS and the hydroxyl group of the epoxy underwent a dehydration condensation reaction to generate a Si-O-C bond,while the FAS molecules were also dehydrated and condensed to form a Si-O-Si bond according to Fourier transform infrared(FT-IR)spectroscopy and X-ray photoelectron spectroscopy(XPS).Therefore,the mechanical property and thermal stability of the HTW were better than the TW based on their tensile tests and thermogravimetric analysis(TGA).Due to the large reduction of hydroxyl in epoxy,the hydrophobicity of the HTW was greatly improved compared with the TW,and their contact angles were 113°and 77°,respectively.The results of scanning electron microscopy(SEM)showed that epoxy was filled in the voids of wood.In addition,the coating of the FAS did not obviously reduce the transmittance,and the transmittance of the TW and HTW was 69%and 67%at 750 nm.All in all,the HTW has potential for application in transparent decoration.

Retrieving structural information from scattering and attenuation data of transparent wood and(Nano)paper

Over the last 15 years,significant number of reports on transparent paper and transparent wood appeared in the literature.The light scattering data or transmission data are often given to describe the optical performance of the material.In addition,the data also contains structural information that can be further analyzed based on scattering theory.Some of the data are re-analyzed herein from structural analysis point of view related to the scattering phenomena.Quantitative analysis on the wavelength dependent optical density of nanopaper suggested that the scatterers are not isolated voids or microfibrils but rather large submicrometric and structural domains.Angular dependence of transparent wood scattering suggests the scattering units of a few micrometers such as cell wall are at the origin of high haze.