Synthesis and Characterization of o-Hydroxybenzophenone Chromophore Bonded to Aminopropyl Silica Gel Microbeads

Abstract

o-Hydroxybenzophenone (Hbp) chromophores were immobilized on 3-aminopropyl silica gel (SiO2–NH2) by a reaction of succinimidyl 4-(4-benzoyl-3-hydroxyphenoxy)butanoate (2a) and -undecanoate (2b) with SiO2–NH2 to produce microbeads 1a and 1b in 25 and 21% yield, respectively. The bond formation was confirmed by appearance of an absorption at 1550 cm−1 due to the N–H bending of the amide bond in the IR spectra of 1a and 1b. In order to enhance the thermal and photochemical stabilities, the 1a and 1b residual amino group was acetylated by Ac2O in CHCl3 to produce 7a and 7b. Acetylation occurred on the aminopropyl group. However, it did not occur on the phenolic OH group of Hbp from the IR spectra where the absorptions of the bending of the methyl group and the bending of the phenolic OH group appeared at 1375 and 1348 cm−1, respectively. By degradation experiments, it was found that thermal and photochemical stabilities were high in 7a and 7b compared with that of 1a and 1b.

Development of acyl-bonded aminopropyl silica gel fillers with low interfacial adhesion energy in a polystyrene matrix

“…15 Silica gel filler is a stable and safe material that has a wide surface area and the ability to adsorb various materials. 3-Aminopropyl silica gel (SiO 2 -NH 2 ) 16,17 can immobilize functional groups through a covalent bond. To develop a high-performance filler that achieves higher adhesion and a lower T g of filler/polymer composites, the surface tension of the acyl-bonded SiO 2 -NH 2 filler (1) can be modified by controlling the amount and length of alkyl chains (Scheme 1).…”