Abstract
Removal of water vapor from humid streams is an essential process in many industrial processes (e.g., air conditioning system). Effective dehumidification has the potential to reduce energy consumption drastically and decrease the overall cost of the process stream. Membranes technology can be used to reduce the energy needed for removing unwanted water vapor from a stream. Various polymeric and mixed matrix membranes have been proposed for gas dehydration and air conditioning systems. Among them, Nexar™, a well-defined pentablock copolymer, has been identified as a promising candidate.
We will show how the internal morphology of Nexar™ films plays a crucial role in efficient water vapor transport. Films with ordered nano-channels of hydrophilic domains present 5 times higher water vapor transport compared to films with disordered domains. When a polymer solution of Nexar™ is cast, it can self-assemble into non-equilibrium morphologies with interconnected sulfonated styrene micro-domains. The nanoscale morphology can be controlled due to the incompatibility between the blocks of the pentablock polymer. Choosing the appropriate solvents can lead to the segregation of micro-domains generating different nanostructures and morphologies. In this work, we use a combination of solvents that generated interconnected hydrophilic nano-channels. Such channels act as “highways” for the transport of water vapor. The transport in Nexar™ films with nano-channels is enhanced to a great extent compared to the disordered structures currently used as presented in Fig. 1.