气体分离

Abstract(#br)A defect-free membrane with a very high gas permeance is greatly attractive to both academia and industry. Thin film composite (TFC) membranes are promising candidates. However, it is always challenging to have a reproducible and up-scalable method to fulfill the needs. Herein, we report a novel and straightforward strategy to fabricate a high-performance hollow fiber composite membrane using a crosslinked polydimethylsiloxane (PDMS) with a high inherent viscosity obtained from a novel post-crosslinking method.

Abstract(#br)A new application for used reverse osmosis (RO) membranes as gas separation membranes was studied. In this regard, firstly, three pretreatment procedures were used to remove the foulants from the surface of used membrane and then they were coated with polydimethylsiloxane (PDMS). The results indicated that PDMS-coated used RO membranes were capable of separating O 2 /N 2 and CO 2 /N 2 . The maximum O 2 /N 2 and CO 2 /N 2 selectivities of coated membranes were 5.9 and 32.5, respectively.

Abstract(#br)The present paper aims to use intelligent methods for prediction of gas permeation in binary-filler nanocomposite membranes containing fumed silica (FS) and octatrimethylsiloxy polyhedral oligomeric silsesquioxane (POSS) nanoparticles incorporated within a polymer matrix of polydimethylsiloxane (PDMS).

Abstract(#br)The invention of polymers of intrinsic microporosity (PIMs) has opened up great opportunities for the developments of high-performance composite membranes which possess both high gas permeance and selectivity. However, it still remains challenging to translate such PIM materials into PIM-related composite membranes with characteristics of high permeance and selectivity.

Abstract\n\t\t\t\t\n\t\t\t\t\tThe introduction of liquid crystals (LCs) has presented an interesting approach to improving gas separation properties in polymeric membranes. A novel polydimethylsiloxane (PDMS)/LC cross-linked membrane was prepared with PDMS containing vinyl groups and LCs containing unsaturated linkages as matrix materials. The chemical structures and LC properties were characterized with FTIR, DSC and thermal polarized optical microscopy. Some influential factors that affect the permeability and transport properties were also studied.

Blend membranes of synthesized polyurethane based on toluene diisocyanate (TDI), polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) with polyamide12-b-PTMG were prepared by solution casting technique. The synthesized polyurethane-polydimethylsiloxane and PU-PDMS/polyamide12-b-PTMG blend membranes were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM).

聚合物膜在气体分离过程中遇到的一个最关键的问题是气体渗透性和选择性之间的权衡效应。本工作旨在开发一种简单而有效的涂层技术，对常用的聚砜( PSF )中空纤维膜进行表面改性，以解决CO2 / CH4和O2 / N2分离的权衡效应。本研究通过在聚醚嵌段酰胺( Pebax )制备的选择性涂层中加入氧化石墨烯( GO )纳米片，制备了多层包复PSF中空纤维。为了防止Pebax涂层溶液渗入膜基片，在基片和Pebax层之间形成了聚二甲基硅氧烷( PDMS )的沟槽层。然后考察GO负载量( 0.0 ~ 1.0wt % )对Pebax层性能和膜性能的影响。XPS数据清楚地显示了膜选择性层中GO的存在，GO掺入量越高检测到的碳的sp2杂化状态越大。在膜层形貌方面，增加GO用量只影响膜表面粗糙度，而不改变整个膜层厚度。结果表明，在Pebax膜层中添加0.8wt % GO可以得到性能最好的多层膜，与未添加GO的膜相比，CO2 / CH4和O2 / N2气对选择性分别提高了56.1 %和20.9 %。这种改进是由于选择性层中曲折路径增加，相对于较小的气体分子( CO2和O2 )，对较大的气体分子( CH4和N2 )产生了更高的阻力。

研究了紫外光照射对无规分段聚酰亚胺-硅氧烷( PIS )共聚物薄膜气体渗透性能的影响。以4，4\"- (六氟异丙基亚甲基)二苯甲酸酐( 6FDA )和3，3\"，4，4\"-苯甲酮四羧酸二酐( BTDA )为原料，以2，4 -二氨基二甲苯( DAM )和不同量的二胺封端聚二甲基硅氧烷( PDMS )低聚物( Mn   =  3000   g / mol )，以7∶3   M的比例进行酯酸亚胺化反应，合成了随机分段共聚物。这些共聚物的溶剂铸膜在365 nm的空气中被紫外光照射，引起交联和光氧化。在温度为35  ℃，上游压力为2 ~ 18   atm  的条件下，测定了H2、O2、N2、CH4和CO2的纯气体透过率.结果表明，PIS系列共聚物的气体透过率降低，紫外交联和光氧化使自由体积减小，所有气体对的选择性提高.