Materials Science and Engineering B 168 (2010) 30–35 Contents lists available at ScienceDirect Materials Science and Engineering B journal homepage: www.elsevier.com/locate/mseb Aminoethylaminopropylisobutyl POSS—Polyimide nanocomposite membranes and their gas transport properties Barnali Dasgupta, Suman Kumar Sen, Susanta Banerjee ∗ Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India article info Article history: Received 17 August 2009 Received in revised form 28 September 2009 Accepted 7 October 2009 Keywords: Polyimide-POSS nanocomposite membrane Thermo-oxidative stability Permeability Selectivity abstract A series of polyimide-POSS (PI-POSS) nanocomposite membranes were prepared using aminoethy- laminopropylisobutyl group functionalized polyhedral oligomeric silsesquioxanes (POSS) as nanofiller. The membranes were characterized by DSC, TGA, AFM, FESEM, XRD, etc. The effects of incorporation of POSS into the four structurally different fluorinated polyimide membranes on their gas transport proper- ties with four gases (CH 4 ,N 2 ,O 2 and CO 2 ) were investigated at 35 ◦ C and at an applied pressure of 3.5 atm. All the nanocomposite membranes showed comparable glass transition temperature values but a little lower thermo-oxidative stability compared to their corresponding untreated polyimide membranes. The Young’s modulus and maximum stress values of the polyimide-POSS membrane were slightly higher than those of the virgin polyimide membranes; however the elongation at break values were lower. POSS nanoparticles were well distributed as observed from FESEM image and AFM study exhibited no significant increase of the roughness of the hybrid membranes. The order of permeability of these gases were found as CO 2 >O 2 >N 2 > CH 4 . The permeability of all the gases through the composite membranes increased significantly with comparable selectivity for different gas pairs, e.g., CO 2 /CH 4 and O 2 /N 2 . © 2009 Elsevier B.V. All rights reserved. 1. Introduction Over the last few decades, there has been growing attention for the use of polymer membranes in the gas separation indus- try, due to their potential energy saving capability compared to more traditional separation techniques [1–4]. Membranes having both high permeability and selectivity are desirable for practical separation. However, the recent polymeric membranes suffer from the typical trade off behaviour between permeability and selec- tivity [5]. Currently, researchers have explored the possibility of using organic–inorganic hybrid materials for various applications due to their extraordinary properties arising from the synergiz- ing effect of both components [6,7]. It has been demonstrated that octafunctioalized POSS (polyhedral oligomeric silsesquiox- anes) offers an efficient route for the development of novel hybrid nanocomposites. The versatile nature of POSS enhances thermal, mechanical properties, oxidative stability, flame retardance, abra- sion resistance and decreases density and water uptake of its polymer composites [8–20]. The cubic silsesquioxane unit pos- sesses a well-defined nanometer-sized structure with high surface area, controlled porosity, and various functionalities. It consists ∗ Corresponding author. Tel.: +91 3222 283972; fax: +91 3222 255303. E-mail address: susanta@matsc.iitkgp.ernet.in (S. Banerjee). of a rigid, hollow silica core with a nanopore diameter of about 0.3–0.4 nm [10]. Moreover, the silsesquioxane units can be tai- lored with different reactive or non-reactive organic groups at the tetravalent Si atoms. The nanoscopic size of POSS substituted with organic functionalities makes them highly soluble in most organic solvents. The organic groups can also be helpful to enhance the compatibility with the polymer matrix by enabling strong physi- cal/chemical interactions. POSS particles have found a wide range of application in the industrial areas from microelectronics to space survivable materials [18]. Since POSS is a building block of zeolite, it can show similar sieving ability as that of zeolites [21]. More- over, smaller size and tailorable organic groups make them more attractive and promising materials for gas separation application [9]. Recently, Rios-Dominguez et al. prepared polystyrene-POSS mixed matrix membranes and evaluate gas transport properties of O 2 and N 2 [22]. The PI-POSS composite membrane showed much higher permeability with comparable selectivity. However, nanocomposite membranes using POSS as nanofiller has not been much exploited for gas separation applications. Among the various classes of polymeric membranes polyimides have attracted much attention over the last two decades as the basic materials for preparing gas separation membranes [23,24]. They are one of the most outstanding classes of high-performance polymers, which exhibit a number of outstanding properties, such as excel- lent thermal and thermo-oxidative stability, solvent resistance, 0921-5107/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2009.10.006