肾上腺素的电化学氧化聚合研究

采用电化学石英晶振阻抗分析法,研究了金电极上肾上腺素(EP)循环伏安电氧化形成聚合膜的过程,并考察了溶液pH对聚合过程的影响。结果表明溶液pH在3.31和7.04间,肾上腺素的氧化产物发生环化反应后,进一步氧化在金电极表面沉积形成聚合膜,并提出了可能的聚合机理,且该聚合膜具有优良的阳离子选择渗透性。     

The diversification of proto-cells driven by membrane permselectivity

We consider how permselectivity as a function of the membrane is related to the cell evolution with an abstract proto-cell model. We construct an autopoietic proto-cell model having primitive auto-catalytic reaction cycle inside. In this model, several primitive membrane substances are assumed to be produced from the reaction cycle and the membrane is assumed to have a permeability to specific chemical species. We show that the permselectivity of the membrane induces the diversification of the cell volume. We discuss how the diversification of the cells is related to the Darwinian evolution. This work was presented in part and awarded as Young Author Award at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Electrodialytic transport properties of heterogeneous cation‐exchange membranes prepared by gelation and solvent evaporation methods

The heterogeneous cation‐exchange membranes were prepared by employing two different methods: immersing the cation‐exchange resin‐loaded membranes in gelation bath; evaporating the solvent upon casting a uniform solution of cation‐exchange resin on a glass plate. The effect of resin loading on the electrochemical properties of the membranes was evaluated. The permselectivity of these heterogeneous membranes and transport number of calcium ions relative to sodium ions was evaluated with respect to the extent of resin loading and the methods of preparation. It is found that the membrane potential, transport number, permselectivity, and relative transport number are prominently high in the solvent evaporation method compared with the gelation method. The transport number of calcium ions relative to sodium ions in the solvent evaporation method increased monotonously with increasing resin loading. However, the increase of resin loading did not influence much on the relative transport numbers in the gelation method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 198–207, 2006     

Development of high performance amine functionalized zeolitic imidazolate framework (ZIF-8)/cellulose triacetate mixed matrix membranes for CO2/CH4 separation

High cost and complex fabrication process of inorganic membranes and lower position of pristine polymeric membranes in the Robeson upper bound curve urged the researchers to develop mixed matrix membranes (MMMs). Cellulose acetate being most commercially used polymer, dominates the market of CO₂ separation mainly because of low cost and environmental friendly resource. In the present study, MMMs consists of amine functionalized zeolitic imidazolate framework (NH₂-ZIF-8) and cellulose triacetate were fabricated for the first time. NH₂-ZIF-8 was used as a filler because the pore size of ZIF-8 is between the kinetic diameter of separating gases (CO₂ and CH₄). Moreover,  NH₂ group attached on the surface of ZIF-8 has affinity with condensable gases like CO₂. Morphology, crystallinity, tensile strength and functional groups of fabricated membranes were investigated using different analytical techniques. Results revealed that the increase of feed pressure has increased CO₂ permeability and decreased permselectivity. However, improvements in gas separation performance were observed with the addition of nanofiller. Best position in Robeson's upper bound curve at 4 bar was obtained with 10 wt% loading with CO₂ permeability and CO₂/CH₄ permselectivity of 218 barrer and 13.84, respectively. The improvement in the gas separation performance with loading is attributed to the increased diffusion coefficients as well as solubility coefficients, which was increased to 33% and 3.8%, respectively.     

Temperature dependency of gas barrier properties of biodegradable PP/PLA/nanoclay films: Experimental analyses with a molecular dynamics simulation approach

Polypropylene (PP)/poly(lactic acid) (PLA)/clay nanocomposite films with various compositions (PP‐rich and PLA‐rich) were prepared. Their structural and barrier properties against CO₂, O₂, and N₂ were investigated. The microstructure of the nanocomposites was studied by scanning electron microscopy, transmission electron microscopy, and wide angle X‐ray scattering. The PP‐rich with 75/25 composition revealed the best barrier properties against all the gases which could be justified according to its microstructure. Selectivity of O₂/N₂ and CO₂/N₂ was also measured. It was found that the addition of nanoclay as a gas barrier component reduced the permeability in both systems. The permselectivity was also reduced in the PP‐rich films while it was increased in the PLA‐rich system. Moreover, the temperature dependency of permeability, selectivity, and permselectivity for PP, PLA, and PP/PLA (75/25) samples was examined. The results showed that the temperature dependence of permeability obeyed an Arrhenius equation and order of activation energy of permeability for O₂, CO₂, and N₂ gases was found to be E_P < E_P/PLA < E_PLA. According to solubility measurements, the order of solubility coefficient for gases was as follows: CO₂ > O₂ > N₂. Finally, the molecular dynamics (MD) simulation was performed to estimate the diffusivity coefficients of the gases and showed that solubility increases with increasing temperature, which was in accordance with the experiments. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46665.     

Mechanical and Gas Barrier Properties of Poly(L-Lactic Acid) by Plasma-Enhanced Chemical Vapor Deposition of SiOx

In this work, poly(L-lactic acid) film was coated with SiO_x by the plasma-enhanced chemical vapor deposition with different deposition times. Compared with the neat poly(L-lactic acid) film, the oxygen (O₂), carbon dioxide (CO₂), nitrogen (N₂), and water vapor permeability of the poly(L-lactic acid)/SiO_x60 film (depositing for 60?min) decreased by 40.7, 30.6, 58.7, and 53.4% at 25°C, respectively. After treated by the SiO_x deposition, the gas permselectivity of the poly(L-lactic acid)/SiO_x60 film, such as α(CO₂/O₂), α(O₂/N₂), and α(CO₂/N₂), increased by 17.2, 43.9, and 67.5% at 25°C, respectively. In addition, Young’s modulus and tensile strength of poly(L-lactic acid)/SiO_x60 film increased by 107.2 and 49.3%, respectively. Moreover, the poly(L-lactic acid)/SiO_x60 films still kept good toughness with an elongation at break of 50.7%.     

PBAT/ZSM-5分子筛共混薄膜的制备与性能

目的 以聚己二酸-对苯二甲酸丁二酯(PBAT)为基材,制备PBAT/ZSM-5分子筛共混薄膜,研究分子筛含量对薄膜性能的影响.方法 通过共混熔融挤出流延法制得含不同质量分数ZSM-5分子筛(0％,1％,3％,5％,7％)的PBAT薄膜,测定分析不同分子筛质量分数对薄膜的颜色、透明性、结构、气体阻隔性、力学性能等性能的影响.结果 随着分子筛质量分数的增加,透明性和断裂伸长率显著降低,抗拉强度先增加后降低,质量分数为1％分子筛的薄膜抗拉强度相对较大,较纯PBAT薄膜增加了12.34％;薄膜氧气透过性能整体上呈上升趋势,二氧化碳透过性和CO2/O2透过比均逐渐增加,水蒸气透过性显著降低,与纯PBAT薄膜相比,质量分数为7％分子筛PBAT薄膜的氧气和二氧化碳透过系数分别增加了18.48％,33.51％,水蒸气透过系数下降了43.28％,CO2/O2透过比由原来的8.84增加到9.96;薄膜表面和横截断面均变得粗糙,局部区域有团聚现象,且随分子筛含量的增加而变得明显.结论 ZSM-5分子筛的少量加入,可以影响PBAT薄膜力学性能,降低其水蒸气透过性,调节薄膜的气体选择透过性,为其应用于生鲜果蔬包装提供基础.     

Development of thin‐film composite hollow‐fiber membranes from modified polyphenylene oxide for gas separation applications

The effect of sulfonation and bromination‐sulfonation on the gas transport properties of polyphenylene oxide has been investigated. These high‐performance modified polymers have been studied in the form of TFC membranes by solution coating on the skin side of polyetherimide hollow fibers. TFC membrane modules prepared from sulfonated‐brominated polyphenylene oxide as the active layer coated on polyetherimide hollow fibers. Stability of the TFC membranes was greatly improved when a wet feed stream was used instead of a dry one. Water vapor in the feed stream most likely prevented the active layer from stress cracking on drying. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 275–282, 2001     

Sorption and diffusion of volatile organic compounds in fluoroalkyl methacrylate‐grafted PDMS membrane

Pervaporation is known as an excellent method for the purification of contaminated water, the extraction of aroma compounds, etc., and has been widely studied. The prediction of permeation is important for treatment, extraction, and quantitative analysis. To predict permeation, a solution–diffusion mechanism is proposed. The octanol–water partition coefficient (Pow) has been generally used in expressing hydrophobicity. The hydrophobicity, Pow, is closely related to the solubility of organic compounds. Also, the molecular volume is closely related to the diffusion of organic compounds. In this study, we improved polydimethylsiloxane (PDMS) membranes by plasma grafting of fluoroalkyl methacrylates (FALMA) to enhance the affinity of PDMS to volatile organic compounds (VOCs). Furthermore, we investigated the pervaporation through the plasma‐grafted PDMS membrane and the PDMS membrane and the solution–diffusion mechanism of various VOCs. The permselectivity of tetrachloroethylene (PCE) and toluene determined by the sorption and the diffusion characteristics permeating in the membrane was high. Because the molecular volume of the VOCs is greated than that of water and the permeates quickly penetrate in rubbery membranes like PDMS, permselectivity was not affected by the diffussivity. Solubility significantly affected the permselectibity during pervaporation through a hydrophobic rubbery membrane. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 773–783, 2000     

Effects of applied potentials on permselectivity of ions through polypyrrole/porous-polypropylene composite membrane

A composite membrane was prepared by the combination of polypyrrole with a porous-polypropylene film, and its permselectivity was investigated. The permeability and selectivity of various sodium salts through the membrane were changed with an applied potential. The permeation of anions at the positive potentials was due to the migration through the positive sites of the polypyrrole layer, as well as the diffusion from the difference of concentration and potential. The contribution of the migration effect to the anion permeation was very large. The main factors dominating the permeation character of different anion species were the size and valence of the anions. The composite membrane worked effectively as a functional separation membrane to control the ionic permeability by potential application. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 647–653, 1998