Assessment of atomic force microscopy for characterisation of nanofiltration membranes

Study of glassy polymers fractional accessible volume (FAV) by extended method of hydrostatic weighing: Effect of porous structure on liquid transport

“…In general, the retention performance of NF membranes is mainly governed by the mean size of free volume elements or ''nanopores'', while the liquid transport is also determined by the fraction of free volume elements and its interconnectivity. By using different experimental techniques including solute retention [5,6], liquid-liquid displacement porosimetry [6], atomic force microscopy (AFM) [5][6][7][8][9][10], positron annihilation lifetime spectroscopy (PALS) [10][11][12], and combination of transmission electron microscope (TEM) with high contrasts like OsO 2 [13,14], the mean size of free volume elements or ''nanopores'' of different NF membranes for both aqueous and non-aqueous applications can be estimated to be at the level of about 0.4-2 nm; the estimated ''pore'' size distribution for the selective layer is relatively well correlated with the nanofiltration performance of the membranes. However, such porosity has little in common with the porosity of conventional microporous adsorbents such as alumina, silica, and carbon molecular sieves.…”

Prediction of single salt rejection in nanofiltration membranes by independent measurements

“…Images of Figure 4.a and c compare the topography in both samples. The two images show a granular structure of the polymeric surface, which is a usual structure for this kind of membranes [48,49].…”

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 17 Figure 5.a shows a scheme of the phase change process when the tip moves from hard to soft areas. Images b and d of Figure 4 show the phase change (in tapping mode) associated to the change in viscoelastic properties of the surface, providing additional information to the topographical projections [49].…”

Surface properties of semi-synthetic enteric coating films: Opportunities to develop bio-based enteric coating films for colon-targeted delivery

“…The peak-to-valley height (R z ), surface skewness (R sk ), and surface kurtosis (R ku ) were calculated using the following formulas (Stawikowska & Livingston, 2013):…”

“…The induced chain entanglements of these polymers can trigger the chains to coil up and decrease the surface area, which in turn results in lower R q and R z -to posses' better moisture and gaseous barrier properties (Stawikowska & Livingston, 2013). The induced chain entanglement of the nanoparticles with pectin and carboxymethylcellulose aids the integrity of the surface (Fig.…”