Texture and micro-nanostructure of porous silicon oxycarbide glasses prepared from hybrid materials aged in different solvents

Surface and Structural Modification of Nanostructured Mesoporous Silicon Oxycarbide Glasses Obtained from Preceramic Hybrids Aged in NH4OH

“…also considered a spatial segregation of oxygen‐rich and carbon‐rich SiO 4− x C x structural units where the carbon‐rich units would be located near the interface of the carbon nanodomains. According to the results obtained in the present work, the structure of silicon oxycarbide glasses described as silica nanodomains separated by graphitic layered clusters fits with the encountered structure . The short range order is promoted in r‐SiOC because of the increase in the physical barrier imposed by the carbon atoms for the silica nanodomains growing.…”

“…Many attempts to describe the structure of the silicon oxycarbide glasses can be found in the literature . Two of the more widespread models are the interpretation of the structure as silica nanodomains surrounded by domain walls of graphene layers with mixed silicon oxycarbide units in the interface, and the other model describes a concept of carbon nanodomains dispersed in a silica matrix.…”

“…In this study, we report on the nanostructured silicon oxycarbide obtained with a narrow bimodal pore size distribution from TREOS and polydimethlylsiloxane (PDMS). Based on previous work, the higher reactivity of the silanes with the hydrogen functionality compared with nonfunctionalized silanes such as tetraethoxysilane (TEOS) allowed the obtaining of silicon oxycarbide glasses with higher surface area than in the materials obtained from the well‐known system TEOS‐PDMS . Here, we study the effects produced in both the structural characteristics and the surface of the obtained ceramics because of the different carbon content and its nature with regard to the potential application of this sort of material in catalytic applications and heterogeneous chemistry.…”

“…Aging and drying conditions have been demonstrated to be crucial in the control of pore size and distribution. In the synthesis of large pieces or monoliths, nonbonded molecules are swept along by the solvent during the course of evaporation, leading to a gradient distribution of the components in the preceramic polymer and thus in the final ceramic . Singh and Pantano obtained mesoporous silicon oxycarbide glasses with narrow pore size distribution when pyrolyzed hybrid gels were synthesized from silicon alkoxides and aged in NH 4 OH solutions.…”

Structure properties relationship in silicon oxycarbide glasses obtained by spark plasma sintering

“…In the case of the samples with Al 2 O 3 , the molar amount of C free phase is considerably higher than expected considering the La parameter and the results obtained in all the other samples. The general trend of increasing carbon nanodomain size with the C free phase is maintained when this reinforcement is used but the encountered small crystallite size suggests that there occurs a segregation of carbon inside the matrix [29,30].…”