Abstract
Tertiary-amine-based Polymers of Intrinsic Microporosity (PIMs) provide a class of highly porous molecularly rigid materials for the electrochemical transport of both ionic and neutral species. Here, the transport of water molecules together with chloride anions (i.e. the electroosmotic drag coefficient) is studied for the intrinsically microporous polyamine PIM-EA-TB immersed in aqueous 0.01 M NaCl (i) when protonated for pH < 4 or (ii) when not protonated for pH > 4. Preliminary data suggest that in both cases a high electroosmotic drag coefficient is observed based on direct H2O transport into a D2O-filled compartment (quantified by 1H-NMR). For PIM-EA-TB there is a strong pH dependence with a higher electroosmotic drag coefficient in less acidic solutions (going from approx. 400 H2O per anion at pH 3 to approx. 4000 H2O per anion at pH 7), although the underlying absolute rate of water transport at a fixed voltage of −1 V appears to be essentially pH independent. Water transport through the PIM-EA-TB microchannels is rationalised based on the relative populations of chloride anions and of water in the micropores (essentially a ‘piston’ mechanism).
Highlights
Water transport and water purification with membranes represent important aspects of technologies that are key to societal challenges such as clean water provision and water harvesting [1], industrial water usage and recycling [2], and reliable irrigation in agriculture [3]
Electroosmotic transport in anionic diodes based on microporous polyamine: Voltammetry
Electroosmotic transport in anionic diodes based on microporous polyamine: Water transport
Summary
Water transport and water purification with membranes represent important aspects of technologies that are key to societal challenges such as clean water provision and water harvesting [1], industrial water usage and recycling [2], and reliable irrigation in agriculture [3]. Electrodialysis is a technique based on ion transport through a membrane and an important side effect of electrodialysis is electroosmosis, the transport of neutral species that accompany ionic species, for example in electroosmotic pumps [8]. Electroosmotic transport of water is investigated in a polymer of intrinsic microporosity (PIM [12]). Ionic current rectification is associated with rectified electroosmotic pumping. The rigid microporous structure of PIM-EA-TB is suggested to be responsible for the very high rate of water transport with elec troosmotic drag coefficients of up to 4000 (compared to 13,000 in porous silica reported by Shin et al [20] or approximately 1 for Nafionbased membranes [21])
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
