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Guoxiong Deng,Yilei Wang,Xueping Zong,Jiangzhou Luo,Xuezhen Wang,Chunxue Zhang,Song Xue 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-
Here we reported a causal relationship between the molecular structure of binaphthol-based polyimideprecursor and the pore-size distribution of the derived carbon membrane. The binaphthol-basedpolyamide acid is synthesized from 2,20-diol-1,10-binaphthyl-6,60-diamine and 4,40-(hexafluoroisopro-pylidene)diphthalic anhydride (6FDA). Then, an azeotropic imidiaztion method was used to synthesizethe polyimide with naphthol groups (XS1). When the imidization is carried out by using acetic anhydride,the polyimide with acetyl groups (XS4) is achieved. The CMS membranes prepared by pyrolyzing XS1 andXS4 at 500, 550, and 600 ℃ are named using the temperature as the suffix, such as XS1-500. Their poreevolution has been investigated using TGA, FTIR, XRD, and Raman measurements. The trimodal pore-sizedistribution is in the carbon molecular sieve (CMS) membranes derived from XS4 and the CMS onesderived from XS1 exhibit a bimodal pore structure. Among them, XS4-500 exhibits the highest gaspermeabilities of 3332 barrer for CO2, 773 barrer for O2, and 119 barrer for N2. XS1-500 only affords theCO2, O2, and N2 permeabilities of 1086, 230, and 30.2 barrer. The esterification of naphthol not justdisturbs the hydrogen bonds between polyimide chains but also affects the pore generation of thederived CMS membranes. Our work provides an effective way to enhance the gas permeability of a CMSmembrane derived from the binaphthol-based polyimide.
Facile Synthesis of Zn1-xCuxO Nanorods with a Very Broad Visible Band
Jianguo Lv,Changlong Liu,Wanbing Gong,Zhenfa Zi,Xiaoshuang Chen,Kai Huang,Feng Liu,Tao Wang,Gang He,Xueping Song,Zhaoqi Sun 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.5
Zn1-xCuxO nanorods with different Cu concentrations are prepared by a hydrothermal method. Bent and aggregated nanorods are obtained, which is attributed to centripetal surface tension of the evaporation and coagulation processes of the water film on the ZnO nanorods. The broad visible band consists of one violet, three blue,and one green emission. The violet emission is due to the transition of electrons from zinc interstitial (Zni)levels to the valance band. The three blue emissions may be attributed to the transition from extended Zni levels, which are slightly below the simple Zni level, to the valance band. The change of the green emission may be the result of competition between oxygen vacancies (VO) and zinc vacancies (VZn).
Influence of Solution Concentrations on Surface Morphology and Wettability of ZnO Thin Films
Jianguo Lv,Changlong Liu,Feng Wang,Zhitao Zhou,Zhenfa Zi,Yuan Feng,Xiaoshuang Chen,Feng Liu,Gang He,Shiwei Shi,Xueping Song,Zhaoqi Sun 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.2
ZnO thin films were grown on silicon substrates using a hydrothermal method. The XRD patterns show that all of the peaks can be attributed to the wurtzite structures of ZnO. The TC value of (002) plane and average crystal size increase first and then decrease with the increase of solution concentration. SEM and AFM results show that many dense hexagonal cylinder particles have been observed on the surface of the thin films, which grown at 0.08 and 0.10 mol/L. The surface roughness of the thin films deposited at 0.06,0.08, 0.10, and 0.12 mol/L are 24.5, 38.3, 32.0, and 39.4 nm, respectively. Surface wettability results show that the preferential orientation along c-axis and surface roughness contribute significantly to the hydrophobicity. The reversible switching between hydrophobicity and hydrophilicity is related to the synergy of the transition of wetting model, surface crystal structure, and surface roughness.