Influence of Synthesis Conditions on Properties of Ethane-Bridged Periodic Mesoporous Organosilica Materials as Revealed by Spin-Probe EPR

Abstract

A thorough investigation of the formation mechanism and surface properties of periodic mesoporous organosilicas (PMOs) is of crucial importance for further tuning and improving of the structural characteristics and applications of these promising meso-structured materials. In the present paper, the effects of the synthesis conditions on the properties of ethane-bridged PMOs were studied by means of spin-probe electron paramagnetic resonance (EPR) spectroscopy complemented with standard characterization techniques for porous materials. When spin probes were dissolved in the synthesis mixture, the influence of the precursor type on the formation kinetics of ethane-bridged PMOs could be tested. The use of the precursor 1,2-(tris(triethoxysilyl)ethane instead of bis(trimethoxysilyl)-ethane significantly slows the pore formation, leading to materials with larger pore diameters. Furthermore, different spin probes with varying sizes and polarities were adsorbed onto two types of ethane-bridged PMOs synthesized a...