Investigation of two bioinspired reaction mechanisms for the optimization of nano catalysts generated from hyperbranched polymer matrices

Silver nanoparticles were templated employing hyperbranched poly (ethylene imines) (PEI). Then they were immobilized to silica substrates also formed by the mediation of the same dendritic polymer matrices to produce hybrid nanocatalysts. The effect of four different PEIs (MW 2000 to 750,000) was investigated. In the first stage, the mechanisms of the already known spontaneous transformation of Ag ions to metal nanoparticles were monitored by UV Visible Spectroscopy and dynamic light scattering (DLS). Then the effect of three different pH regulating agents on the formation of SiO 2 at pH 7,5 was investigated. An additional optional step, the organic scaffold pyrolysis and the repercussions to the catalytic activity was researched as well. This treatment accelerated reactants' diffusion into silica, eliminated induction periods, and improved reaction rates. Furthermore, compatibility with reactions at high temperatures was established. The characterization of the resulting materials also involved, thermogravimetry (TG), FTIR spectroscopy, ζ-potential, and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS). Kinetic studies were conducted to investigate catalytic performance and the effect of the different composite formation methods on the accessibility to the silver nanoparticles. The majority of the samples tested, exhibited excellent results. Taking into account the ecological synthesis procedure that is carried out at ambient temperature without toxic compounds or solvents the overall procedure emerges as a prosperous alternative for the production of a wide range of multifunctional nanomaterials. • 2 biomimetic approaches for the production of multifunctional materials. • Two different (polymer MW dependent) silver ion reduction mechanisms. • Substantial influence of buffering agents on the composite's properties. • Catalyst performance analogous to accessibility (and not quantity) of silver. • High-temperature treatment causes disparate catalytic efficiency increase.