New fabrication methods for high performance CO2 capture membranes

Despite the development of many new polymeric materials for CO2 capture membranes, only few membranes have arrived to testing at pilot scale. This clearly indicates the need of new strategies for membrane fabrication. One of membrane preparation approaches employed in the POLYMEM project is based on modifying in precise and controlled manner polymers and their membrane surfaces with CO2 reactive groups. This represents a new approach in gas separation membranes that mitigates the risks associated with use of polymer blends, addition of various CO2 enhancement materials (nanoparticles, etc): incompatibility between materials, poor and limited dispersion of particles and difficulty in preparing membranes. We will report membranes preparation by using UV grafting of poly(trimethylslilylproyne) (PTMSP), polydimethylsiloxane (PDMS), polyvinyl alcohol PVA, membranes with CO2 -philic groups and will discuss the influence of various parameters on membranes structure and their separation performances. The density of the grafting can be varied by varying the initiator concentration, and the length of the polymer chains grafted on the surface can be varied by varying both the monomer concentration and the UV exposure time. The membranes structure is characterized by SEM pictures and FT-IR. The density of grafted amino groups on membrane surface is determined by an innovative method and is correlated with the results from mixed gas permeation testing using a synthetic flue gas: 10 % CO2 in N2, fully humidified. It was observed that uniformity of the surface grafting play a major role on membranes separation properties and is dependent on various factors such as grafting conditions, contact angle, type of solvents used etc. Excessive crosslinking due to some grafting conditions and certain monomers reduced the expected CO2 flux, and needed to be further investigate and eliminate.