Investigation of amino and amidino functionalized Polyhedral Oligomeric SilSesquioxanes (POSS®) nanoparticles in PVA-based hybrid membranes for CO2/N2 separation

Hybrid membranes were prepared using amino-functionalized Polyhedral Oligomeric SilSesquioxanes (POSS (R)) nanoparticles, with polyvinyl alcohol (PVA) and dip coated on Polyphenylene Oxide (PPO) as support. Different functionalities of amino and amidino POSS (R) have been developed and evaluated for CO2/N-2 separation in order to understand the polymer/nanoparticle interaction and their impact on the CO2 transport mechanism. CO2 absorption and desorption studies were carried out to understand the chemical behavior of the CO2 transport phenomena in solution. The as-obtained hybrid selective membrane materials were analyzed using various techniques, such as TGA, DSC, FT-IR, and XRD, while the gas permeation properties were evaluated in a CO2/N-2 mixture at room temperature. The membranes prepared with the amino-and amidino-functionalized particles show a CO2 permeability of 0.53 and 0.71 m(3)(STP)/m(2) bar h, respectively at a CO2/N-2 selectivity of around 40. Differences are explained through CO2 absorption and desorption studies performed in solution showing a higher CO2 cyclic capacity for the amidino particles. However, when comparing these results with the bare PPO/PVA system, no clear advantageous effect of the addition of the nanoparticles was observed. Due to the interaction of the nanoparticles with the polymer matrix, the particles do not exhibit a carrier transport in the composite membranes. The addition of the amino and amidino POSS (R) showed that the expected increase in CO2 permeance is not reached due to the interaction of the nanoparticles with the polymer matrix. Moreover, the amino & amidino POSS (R) do not exhibit a carrier transport in the composite membranes.