For PAN fibers, this can be clearly explained by TEM images: at a higher temperature, some of the AgNPs were formed inside the matrix and, therefore, they might not be accessible to the reagents. Although almost all of the nanocomposites exhibited good catalytic activity for the reduction of 4-np, an induction time was needed for the reaction to proceed at high extent. This induction time has also been observed in other works for PdNPs [9, 11, 19, 20], where it has usually been suggested that H2 evolved from the decomposition
of NaBH4 can be loaded inside PdNPs competing with the catalytic reaction. Thus, once the absorption of H2 has reached a saturation value, the catalytic reaction prevails. As far as we know, in the case of silver, this situation has not been already described but is very compatible with the experimental Foretinib in vivo results. In fact, taking into account the well-known and fully accepted Langmuir-Hinshelwood mechanism for the reduction of 4-np to
4-ap , there is a first step during the reaction that involves the loading of the catalytic nanoparticles with hydride (H−). Figure 6 illustrates the aforementioned mechanism. Figure 6 Langmuir-Hinselwood mechanism for the reduction of 4-np to 4-ap with NaBH 4 . Conclusions The synthesis AgNPs in PUFs and textile fibers was successfully achieved: small nonaggregate MNPs were obtained in all of the matrices and mainly
Amobarbital located on the surface. Neither acid nor basic pretreatments significantly affected the metal loading in PUFs. Veliparib manufacturer Instead, a tuning effect of the matrix after applying see more different pretreatments was observed, since the AgNPs distribution and size depended on the treatment. For textile fibers, the higher the temperature of synthesis, the higher the metal loading, very probably due to macromolecular chains mobility. In addition, for PAN fibers, the temperature significantly affected the spatial distribution of AgNPs due to the low values of the glass transition temperature. Almost all of the nanocomposites exhibited good catalytic activity for the reduction of 4-np, although an induction time was needed for the reaction to proceed at high extent. From these results, it comes that catalytic efficiency not only depends on the metal loading but also on the MNPs’ diameter and their spatial distribution. Finally, these results prove that matrices not bearing ion-exchangeable groups can also be successfully used for nanocomposites synthesis by IMS. Acknowledgments We thank ACC1O for VALTEC09-02-0058 grant within the ‘Programa Operatiu de Catalunya’ (FEDER). Special thanks are given to Servei de Microscòpia from Universitat Autònoma de Barcelona. References 1. Dioos BML, Vankelecom IFJ, Jacobs PA: Aspects of immobilisation of catalysts on polymeric supports. Adv. Synth. Catal. 2006, 348:1413–1446.CrossRef 2.