Results and discussion The efficiency of the final application of PMNCs (e.g.,

in catalysis [4, 5, 16] or in complex water treatment [3, 15]) strongly depends on the distribution of FMNPs in the polymer. The IMS technique coupled with the Donnan exclusion effect (DEE-IMS) was shown to allow for achieving the desired distribution of FMNPs near the surface of the hosting polymer [2–4, 17, 18]. The metal reduction stage of IMS in our case is described by the following equation: (1) Equation 1 is in fact the sum of the following two equations: (2) (3) The use of an ionic reducing agent (BH4 −) bearing the same charge as the functional groups of the polymer is the key point DEE-IMS. Indeed, the polymer matrix bears negative charges due to the presence of well-dissociated

LY3023414 clinical trial functional groups (sulfonic). The borohydride anions also bear negative charges and therefore cannot deeply penetrate inside the matrix due to the action of electrostatic repulsion. The depth of their penetration inside the matrix is balanced by the sum of two driving forces acting in the opposite directions: (1) the gradient of borohydride concentration and (2) the DEE [19] The action of the second force limits deep penetration of borohydride anions into the matrix so that reaction (3) proceeds in the surface zone of the polymer see more which results in the formation of MNPs mainly near the surface of the matrix. The reduction of metal ions with sodium borohydride results in the conversion of functional groups into the initial Na form which permits repetition of the metal loading-reduction cycle (without special resin pretreatment) for increasing the MNP content

in FMNPs mainly on the polymer surface (Figure 1). Figure 1 SEM image and line scan EDS spectra. (A) High-resolution SEM image of the cross section of Purolite C100E resin modified with Ag-MNPs. (B, C) Line Scan EDS spectra showing distribution of Ag-MNPs in PMNC. The appearance Palmatine of Ag-MNPs in the gel-type polymer is accompanied by their interaction with polymer chains (see Figure 2C) which results in the dramatic changes of polymer surface morphology and appearance of nanopores, wherein the diameter appears to depend on the MNP content in FMNPs (see Table 1). Figure 2 Schematic diagram and SEM images. Schematic diagram of the interaction of MNPs synthesized inside (B) the polymer matrix and SEM images of Purolite C100E resin surface (A) before and (C) after IMS of Ag-MNPs. Table 1 Increase of pore diameters in Ag-MNP-containing Purolite C100E resin samples Sample Ag-MNP content (mg/g) BET average pore diameter (nm) C100E 0 1.9 Ag-C100E PMNC (5a) 112.7 ± 0.5 2.3 ± 0.2 Ag-C100E PMNC (10a) 143.5 ± 0.5 4.4 ± 0.2 aNumbers show the time of metal loading cycle carried out. As it is clearly seen in the SEM images shown in Figure 2, the initially selleckchem smooth polymer surface (see Figure 2A) dramatically changes after IMS of Ag-MNPs (Figure 2B,C) due to the appearance of a ‘worm-like’ morphology.