, Tokyo, Japan). Before observation, the samples were deposited between two plastic sheets in an epoxy resin, and ultra-thin slices were obtained using an ultra-microtome. Catalytic properties evaluation The catalytic performance of nanocomposites was evaluated by using the reduction of 4-np to 4-ap by NaBH4 as a model reaction, which was considered to follow a pseudo-first-order kinetics, and the apparent rate constant (k app) was calculated. In a typical run, a piece of nanocomposite (1 cm2 for textile fibers and 1 cm3 for PUFs) was added to a vessel of 50 ml solution containing 4-np (0.5 mM) and NaBH4 (500 mM). The process was monitored at 390 check details nm by a PLK inhibitor Pharmacia LKB Novaspec II spectrometer (Biochrom

Ltd., Cambridge, UK). Results and discussion Characterization of the polyurethane foams and their pretreatments PUF resulted to be a very stable material. The FTIR-ATR spectra of PUFs (Figure 2) show the distinctive polyurethrane (PU) bands [17]: the broad peak at 3,270 cm−1 is characteristic of the υ(N-H), the peaks at 1,690 and 1,520 cm−1 are typical for υ(C=O) (urethane band) and δ(NH)

with υ(CO-N) (amide II). Surprisingly, no differences between spectra were observed. Thus, no chemical modification took place after any pretreatment. In addition, as seen in Table 1, similar values of IEC were obtained in all the cases, which also pointed out that a basic or acid pretreatment did not significantly affect the presence of ion-exchangeable positions. Figure 2 FTIR-ATR of PUFs before and after pretreatments.

Table 1 PUF IEC values   IEC (meq/g) Treatment Acid groups EX527 Basic groups Blank 0.65 0.62 NaOH 1M 0.32 0.61 NaOH 3M 0.57 0.61 HNO3 1M 0.66 0.71 HNO3 3M 0.61 0.57 IEC, ion exchange capacity. Uncertainty in all of the cases was <1%. Nanocomposites characterization After applying the IMS technique, a darkening of the matrices was observed, indicative of the metal loading. The color for modified PUFs was similar, but clear differences in color intensity were detected for textile fibers: the higher the temperature, the darker the color. For PUFs, the metal content did not increase after pretreatments. On the one hand, a basic pretreatment allowed loading of metal in a similar way compared to untreated foams, whereas acid treatments http://www.selleck.co.jp/products/CHIR-99021.html resulted in a lower metal concentration (Figure 3). A priori, both treatments were expected to increase the total metal loading due to the formation of ionogenic groups. However, since no new ionogenic groups were generated (as concluded from the FTIR-ATR and from the IEC values), the loading of the Ag+ can be attributed to coordination with lone electron pairs of nitrogen atoms. Accordingly, the acid/basic treatments just ‘tune’ the possibility of coordination bonds to happen (depending on the isoelectric point of the matrix). Figure 3 Results of the ICP-MS analysis of the Ag content in (a) PUFs and (b) PAN and PA fibers.