Electro-osmotic properties of porous permeable films

Thermo-osmotic transport in nanochannels grafted with pH-responsive polyelectrolyte brushes modelled using augmented strong stretching theory

“…This ensures that the contribution of the drag force will be significantly lower since the drag force is calculated by multiplying the drag coefficient with the local velocity and this velocity is smaller at near-wall locations. It might be possible that this overprediction of the drag force in the studies by the other groups (Yeh et al 2012a,b,c;Benson et al 2013;Milne et al 2014;Zeng et al 2014Zeng et al , 2015Poddar et al 2016;Zhou et al 2016;Zimmermann et al 2017;Sadeghi 2018;Sin & Kim 2018;Hsu et al 2019;Huang & Hsu 2019;Lin et al 2019;Reshadi & Saidi 2019;Sadeghi et al 2019;Khatibi et al 2020;Sadeghi et al 2020a,b;Silkina et al 2020;Talebi et al 2021;Wu & Hsu 2021) might have made them miss this enhancement in the electrokinetic transport in brush-grafted nanochannels and that is why they do not provide any explicit comparison between the flow field in a brush-grafted nanochannel with that in a brush-free nanochannel under the condition where the net charge on the wall (for the case of brush-free nanochannel) is distributed on the brushes (for the case of brush-grafted nanochannel). There is another critical issue that has been overlooked by all of these above-mentioned papers, including our own papers.…”

“…Without such a comparison, it is not possible to decipher if the results of these papers (Yeh et al 2012a,b,c;Benson et al 2013;Milne et al 2014;Zeng et al 2014Zeng et al , 2015Poddar et al 2016;Zhou et al 2016;Zimmermann et al 2017;Sadeghi 2018;Sin & Kim 2018;Hsu et al 2019;Huang & Hsu 2019;Lin et al 2019;Reshadi & Saidi 2019;Sadeghi et al 2019;Khatibi et al 2020;Sadeghi et al 2020a,b;Silkina et al 2020;Talebi et al 2021;Wu & Hsu 2021) would have shown (for some parameter combination) a flow field that is enhanced in brush-grafted nanochannels, as compared with that in brush-free nanochannels. The second issue is the overprediction of the drag force in these papers (Yeh et al 2012a,b,c;Benson et al 2013;Milne et al 2014;Zeng et al 2014Zeng et al , 2015Poddar et al 2016;Zhou et al 2016;Zimmermann et al 2017;Sadeghi 2018;Sin & Kim 2018;Hsu et al 2019;Huang & Hsu 2019;Lin et al 2019;Reshadi & Saidi 2019;Sadeghi et al 2019;Khatibi et al 2020;Sadeghi et al 2020a,b;Silkina et al 2020;Talebi et al 2021;Wu & Hsu 2021). The drag coefficient dictating the drag force is the gross representative contribution of the presence of the brushes.…”

“…It is considered to vary quadratically with the monomer distribution. The existing papers (Yeh et al 2012a,b,c;Benson et al 2013;Milne et al 2014;Zeng et al 2014Zeng et al , 2015Poddar et al 2016;Zhou et al 2016;Zimmermann et al 2017;Sadeghi 2018;Sin & Kim 2018;Hsu et al 2019;Huang & Hsu 2019;Lin et al 2019;Reshadi & Saidi 2019;Sadeghi et al 2019;Khatibi et al 2020;Sadeghi et al 2020a,b;Silkina et al 2020;Talebi et al 2021;Wu & Hsu 2021) did not explicitly model the brushes and simply considered a uniform monomer distribution. Therefore, the drag coefficient has a constant value along the entire height of the grafted brushes.…”

Surface and zeta potentials of charged permeable nanocoatings

“…In most of these studies weakly charged surfaces or thick compared to the Debye length porous films have been considered [14,[23][24][25]. Very recently Silkina et al [26] reported a closed-form analytic solution for Ψ 0 , obtained without a small potential assumption, which is valid for porous films of any thickness. These authors also proposed a general relationship between Ψ s and Ψ 0 , but made no attempts to derive simple asymptotic approximations for surface potentials that could be handled easily.…”

“…These profiles can be calculated assuming that electrostatic potentials are low [14], but such an assumption becomes unrealistic in many situations. Recently, Silkina et al [26] derived rigorous upper and lower bounds on Z of non-thick films, by lifting an assumption of low electrostatic potential. However, we are unaware of any prior work that investigated the connection of the zeta potential of non-thick films with their finite hydrodynamic permeability.…”