含钴PDMS／三甲基硅基甲基纤维素复合膜的富氧性能研究

以乙烯基质量分数为5％的硅橡胶为基质材料,加入一定量的三甲基硅基甲基纤维素,以含氢硅油为交联剂、氯铂酸为催化剂,通过硅氢加成反应,将羧酸钴结构键合到膜内的交联网络中,室温硫化成膜。膜的富氧性能研究表明,在硅橡胶交联网络中,混入三甲基硅基甲基纤维素,不仅提高了分离系数,也改善了成膜性和膜强度。由于三甲基硅基甲基纤维素（TMS—MC）的混入,20℃时氧氮分．离系数（αO2/N2）升高到3．7,透氧系数（PO2）稍有降低为437Barrer。     

甲基纤维素三甲基硅醚的合成、表征及性能研究

通过甲基纤维素与六甲基二硅亚胺的反应,成功地实现了对水溶性物质甲基纤维素醚三甲基硅化的改性;红外光谱验证了反应的发生,核磁共振氢谱确定了三甲基硅甲基纤维素的取代度;纤维素醚上的部分羟基被三甲基硅化后取得了在普通溶剂中的良好的溶解性,且随着取代度的增加,在非极性溶剂中的溶解性逐渐变好;通过热失重实验,对其热稳定性进行了测试。     

双(三甲基硅基)二亚胺的合成研究

以双(三甲基硅基)氨基锂为起始原料,分别与氯化亚砜、三溴化磷反应,合成了双(三甲基硅基)硫二亚胺和双(三甲基)硅胺基-三甲基硅亚氨基磷,然后通过两者间的硫原子迁移反应,合成了标题化合物.通过梯度温度下的减压冷凝,实现了目标化合物的分离和纯化,并采用核磁共振、紫外-可见吸收光谱进行了结构表征,根据最大吸收波长计算得其跃迁能为2.53 ×10-19J.     

一步法合成3-羟基-6-O-甲基红霉素

利用克拉霉素生产过程中的前体2',4″-O-二(三甲基硅基)-6-O-甲基红霉素A 9-O-(1-乙氧基环己基)肟为原料,一步反应实现脱除2'-三甲基硅基、4″-三甲基硅基、9-O-(1-乙氧基环己基)、9-肟基四个保护基及脱克拉定糖5个反应,得到3-羟基-6-O-甲基红霉素,总得率88%.     

羟丙甲基纤维素衍生物的合成及其原位凝胶的制备

本研究以羟丙甲基纤维素、己基异氰酸酯、氮甲基吡咯烷酮等为原料,二月桂酸二丁基锡为催化剂,采用一步法,制备了一种羟丙甲基纤维素衍生物,该衍生物是一种聚氨酯材料。采用傅里叶红外光谱仪(FT-IR)对制得的聚氨酯进行了结构表征。同时,将制得的羟丙甲基纤维素衍生物溶解于氮甲基吡咯烷酮可制备得到溶剂移除沉淀型原位凝胶。     

SiC/Si_3N_4陶瓷前驱体的合成

通过在六甲基环三硅氮烷中加入部分甲基氢二氯硅烷的氨解产物 (CH3 HSiNH )x ,经氢化钾催化制备了聚硅氮烷 ;用热重分析法研究了其裂解性能 ,考察了反应原料比例、溶剂对陶瓷产率的影响 ;结果表明 :溶剂和原料比例不仅影响聚硅氮烷的性能 ,且对陶瓷产率有重要影响。以四氢呋喃做溶剂可得到较高的陶瓷产率。     

羟基封端聚甲基苯基硅氧烷的制备及表征

以低摩尔质量的羟基硅油和甲基苯基环硅氧烷为原料、四甲基氢氧化铵[(CH3)4NOH]硅醇盐为催化剂,通过平衡共聚反应制备了羟基封端聚甲基苯基硅氧烷.研究了原料配比、催化剂用量、反应时间、反应温度等因素对聚合物制备的影响.通过红外光谱,热裂解气质联用等方法对制备的产物进行了结构表征.结果表明,当(CH3)4NOH质量分数为0.04%, 反应温度110 ℃,反应时间为6 h,甲基苯基硅氧链节与二甲基硅氧链节的量之比为1:1,可制得不同苯基含量的羟基封端聚甲基苯基硅氧烷.     

N,N′-双(三甲基甲硅基)脲的合成

本文主要研究了以三甲基氯硅烷为原料制备N,N′双(三甲基甲硅基)脲,对催化剂种类、反应温度和原料摩尔比等工艺条件进行了探讨及优化。在本文的最佳条件下,N,N′双(三甲基甲硅基)脲的收率按三甲基氯硅烷计可达57%。     

1-(2-三甲基硅氧乙基)-5-巯基四氮唑的合成研究

以乙醇胺为起始原料,经三甲基氯硅烷保护制得2-(三甲基硅氧基)乙胺,再经与二硫化碳反应,再与溴乙烷缩合得到N-(2-三甲基硅氧乙基)二硫代氨基甲酸乙酯、然后再与叠氮化钠成环反应合成了1-(2-三甲基硅氧乙基)-5-巯基四氮唑.用三甲基氯硅烷作为乙醇胺的羟基保护试剂,保护和脱保护具有反应条件温和、收率高等 优点,反应总收...     

羟丙基甲基纤维素（HPMC）发展状况和开发前景

一、概况 羟丙基甲基纤维素(HPMC)是纤维素醚工业中产量最低、物化性能最好、用途最广泛的纤维素醚类,属于非离子型高分子化合物。与离子型甲基羧甲基纤维素不同,它与重金属不起反应。根据其成品中甲氧基含量和羟丙基含量的比例不同,可得到在性能上有所差别的各个品种。 HPMC实际上是一种经环氧丙烷改性的甲基纤维素,故它具有与甲基纤维素相类似的冷水溶解和热水不溶的特性。HPMC在有机溶剂中的溶解性优于其水溶性,它能溶于甲醇和乙醇溶     

聚环糊精填充PDMS渗透蒸发膜分离苯酚水溶液

以聚二甲基硅烷为预聚体,正硅酸乙酯为交联剂,二丁基二月桂酸锡为催化剂,三氯甲烷或正庚烷为溶剂,通过相转化法制备得到了空白聚二甲基硅氧烷（PDMS）膜和聚环糊精（CDP）填充PDMS（CDP-f-PDMS）膜.考察了空白PDMS膜和CDP-f-PDMS膜对苯酚水溶液的渗透蒸发分离性能,证明填充膜优于空白膜.还分别考察了溶剂类型、填充剂用量等制膜因素和操作温度、原料液流量、原料液浓度等操作因素对PDMS膜的渗透蒸发分离性能的影响.当温度为60℃,CDP填充量为1%（质量）时,CDP-f-PDMS膜的渗透通量和分离因子分别可达32.0 g•m-²•h^-1和7.2.     

石墨填充聚乙烯醇膜渗透蒸发分离苯和环己烷

采用液相共混法制备了石墨填充聚乙烯醇膜,采用FTIR,SEM,XRD等对石墨填充聚乙烯醇膜的物理和化学结构进行了分析表征,结果表明石墨与聚乙烯醇存在较强的氢键作用,石墨在聚乙烯醇中分散均匀,且具有一定的取向性.考察了石墨填充聚乙烯醇膜在苯和环己烷溶液中的溶胀和吸附行为.采用正电子湮没寿命谱仪表征了石墨聚乙烯醇膜的自由体积特性,计算得到石墨聚乙烯醇膜的表观自由体积分数,并且与渗透通量进行关联性对比.最后,研究了石墨含量和粒径对渗透蒸发分离性能的影响,结果表明,石墨的引入有利于苯的优先透过,石墨填充聚乙烯醇膜对苯和环己烷混合物具有良好的分离效果,苯的渗透通量和分离因子分别可达90.7 g•m^-2•h^-1和100.1.     

Divinyl benzene cross‐linked HTPB‐based polyurethaneurea membranes for separation of p‐/o‐xylene mixtures by pervaporation

Cross‐linked hydroxy terminated polybutadiene (HTPB)‐based polyurethaneurea (PU), HTPB‐divinyl benzene (DVB)‐PU, was synthesized by a three‐step polymerization process. It was first used as membrane material to separate p‐/o‐xylene mixtures by pervaporation (PV). The effects of the content of cross‐linker DVB, feed concentration, and operating temperature on the PV performance of HTPB‐DVB‐PU membranes were investigated. The membranes demonstrated p‐xylene permselectivity as well as high total flux. The introduction of DVB significantly enhanced the temperature resistance ability of the HTPB‐DVB‐PU membranes. With increasing DVB content, the separation factor increased while the total flux decreased a little. The highest separation factor reaches 2.01 and the total flux is 33 g/m²h with feed concentration of 10 wt % p‐xylene at 30°C. These PV performances with increasing DVB content were explained in terms of the view point of chemical compositions and physical structures of the HTPB‐DVB‐PU membranes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Methoxy poly (ethylene glycol) methacrylate-TiO2/poly (methyl methacrylate) nanocomposite: an efficient membrane for gas separation

Polymer/nanoparticle mixed matrix membranes (MMMs) is one of the most important topics in gas separation field. In this study, to improve gas separation efficiency, methoxy poly(ethylene glycol) methacrylate (MPEG) was grafted on TiO₂ surface and was used for synthesis of poly (methyl methacrylate) (PMMA) MMMs. Gas permeation and separation properties of PMMA/PMPEG-TiO₂ MMMs were studied for CO₂, CH₄, O₂, and N₂ gases. The results showed that the MMM filled with 5 wt% PMPEG-TiO₂ nanoparticle exhibited optimal separation performance with CO₂ permeability of 32.48 Barrer and CO₂/N₂ selectivity of 56.98, which are higher than pure polymer (2.75 Barrer and 36.71).     

PVAm/PAN复合膜的制备及其对CO2/CH4的分离性能

New polymeric membrane materials——polyvinyl amine (PVAm) with different primary amine contents were synthesized.By covering polyacrylonitrile(PAN) ultrafiltration membranes with PVAm, the PVAm/PAN composite membranes for CO₂/CH₄ separation were prepared. The composite membranes containing more primary amino groups have higher selectivity for CO₂/CH₄.The cross-linking of acid or glutaradehyde could improve the gas permselectivity of the composite membranes. With decreasing CO₂ content in the feed gas, the CO₂/CH₄ separation factor increased.When the feed gas was 25%(vol) CO₂ and 75%(vol) CH₄, the CO₂ permeation rate was 4.1×10^-9cm³(STP) •cm^-2•Pa^-1•s^-1, and the CO₂/CH₄ separation factor was 180.     

Preparation and high oxygen‐enriching properties of cross‐linking polydimethylsiloxane/SiO2 nanocomposite membranes for air purification

Nanocomposite membrane based on polydimethylsiloxane (PDMS) and nanoscale SiO₂ particles were prepared by a convenient and mild sol–gel copolymerization of tetraethoxysilane as well as cross‐linking reaction. The oxygen‐enriching properties of cross‐linking PDMS/SiO₂ nanocomposite membranes containing different silica conversion and SiO₂ contents were investigated. The results showed that the nanocomposite membranes exhibited good membrane‐forming ability, superior mechanical properties, and high solvent resistance as well as excellent oxygen‐enriching properties for air purification. The oxygen‐enriching performance was regulated by the organic/inorganic ratio and silica conversion in the sol–gel synthesis process. Permeability and selectivity could increase simultaneously with the addition of nanoscale SiO₂. The oxygen permeation coefficient of the nanocomposite membrane increased to 680 Barrer and oxygen/nitrogen separation factor kept 3.0 or so, both higher than those of the corresponding pure PDMS membrane. The high oxygen‐enriching properties of the nanocomposite membranes arose from the introduction of SiO₂ particles, the sol–gel copolymerization, and cross‐linking method. © 2012 American Institute of Chemical Engineers AIChE J, 59: 650–655, 2013     

Carbon molecular sieve gas separation membranes based on an intrinsically microporous polyimide precursor

We report the physical characteristics and gas transport properties for a series of pyrolyzed membranes derived from an intrinsically microporous polyimide containing spiro-centers (PIM-6FDA-OH) by step-wise heat treatment to 440, 530, 600, 630 and 800 °C, respectively. At 440 °C, the PIM-6FDA-OH was converted to a polybenzoxazole and exhibited a 3-fold increase in CO₂ permeability (from 251 to 683 Barrer) with a 50% reduction in selectivity over CH₄ (from 28 to 14). At 530 °C, a distinct intermediate amorphous carbon structure with superior gas separation properties was formed. A 56% increase in CO₂-probed surface area accompanied a 16-fold increase in CO₂ permeability (4110 Barrer) over the pristine polymer. The graphitic carbon membrane, obtained by heat treatment at 600 °C, exhibited excellent gas separation properties, including a remarkable CO₂ permeability of 5040 Barrer with a high selectivity over CH₄ of 38. Above 600 °C, the strong emergence of ultramicroporosity (<7 Å) as evidenced by WAXD and CO₂ adsorption studies elicits a prominent molecular sieving effect, yielding gas separation performance well above the permeability-selectivity trade-off curves of polymeric membranes.     

Quest for high performance carbon capture membranes: Fabrication of SAPO-34 and CNTs-doped polyethersulfone-based mixed-matrix membranes

Gas separation process is an effective method for capturing and removing CO₂ from post-combustion flue gases. Due to their various essential properties such as ability to improve process efficiency, polymeric membranes are known to dominate the market. Trade-off between gas permeability and selectivity through membranes limits their separation performance. In this study, solution casting cum phase separation method was utilized to create polyethersulfone-based composite membranes doped with carbon nanotubes (CNTs) and silico aluminophosphate (SAPO-34) as nanofiller materials. Membrane properties were then examined by performing gas permeation test, chemical structural analysis and optical microscopy. While enhancing membranes CO₂ permeance, SAPO-34 and CNTs mixture improved their CO₂/N₂ selectivity. By carefully adjusting membrane casting factors such as filler loadings. Using Taguchi statistical analysis, their carbon capture efficiency was improved. The improved mixed-matrix membrane with loading of 5 wt% CNTs and 10 wt% SAPO-34 in PES showed highly promising separation performance with a CO₂ permeability of 319 Barrer and an ideal CO₂/N₂ selectivity of 12, both of which are within the 2008 Robeson upper bound. A better mixed-matrix membrane with outstanding CO₂/N₂ selectivity and CO₂ permeability was produced as a result of the synergistic effect of adding two types of fillers in optimized loading.