Effects of pH and Dye Concentration on the Optical and Structural Properties of Coumarin-4 Dye-Doped SiO₂-PDMS Xerogels

Vibrational spectroscopic studies of sol–gel derived physical and chemical bonded ORMOSILs

“…The relative intensity of d( LO , the symmetric stretching mode at $800 cm À1 ; m as (Si-OSi) TO , the asymmetric stretching modes at $1075 cm À1 and m as (Si-O-Si) LO (shoulder) at $1180 cm À1 , was slightly reduced for the xerogels, S1 and Cl with 5-10 wt% of PEG. As observed [20,[26][27][28], this modification corresponds to decrease in porosity or increase in density of the system. An up shift in the m as (Si-O-Si) TO band and a down shift in the d(Si-O-Si) band of S1 and Cl with 5-10 wt% of PEG was also noted.…”

“…The FT-IR and Raman spectra (data not shown) of the sono gel (S2) were found similar to the spectra of S1. The S3 also exhibited spectra as S2 with two characteristic PDMS (Si-CH 3 ) bands at $850 cm À1 due to q r (CH 3 ) and $1268 cm À1 due to d s (CH 3 ) [24][25][26][27][28]. The increase in irradiation time (2-15 min) resulted in spectra similar to the S1 with 10 wt% of PEG.…”

“…Appearance of a distinct broad band at $558 cm À1 in the FT-IR spectra of the S1 and Cl xerogels with 5-10 wt% of PEG showed the presence of structural defect or residual cyclic structures in the silica network having four-membered siloxane rings [26][27][28][29][30][31][32]. The increase in content or molecular weight of PEG largely intensified this defect band indicating an increase in the proportion of four-membered siloxane groups instead of six-membered rings.…”

Immobilized ruthenium complexes and aspects of their reactivity

“…Also, they can be prepared in different sizes and shapes, including thin films, monoliths, membranes and powders [33,[80][81][82]. In addition, the mild conditions used in this process make it suitable for the immobilization of such different species as dyes [83], metal complexes [18,21,32] and even proteins [84,85]. Compared with silica gel, this method may allow for a larger load of complex since the entrapment is not limited by the density of functional groups, as in the case of the silica surface.…”

Preparation and antifrictional properties of surface modified hybrid fluorine-containing silica particles

“…The first represents occlusion of an organic molecule in a SiO 2 matrix formed at a solgel process using tetraalkoxysilanes [1]. In this case, on the surface of the inorganic phase the SiO 2 particles are modified due to physical adsorption of organic molecules in the reaction zone.…”