Acid-based resorcinol-formaldehyde xerogels synthesized by microwave heating

Abstract

The polymerization reaction that takes place between resorcinol and formaldehyde is spontaneous but slow. For this reason, compounds are often used to increase the reaction rate and reduce the synthesis time. These compounds can be basic or acidic and their nature and concentration can be used to modify the mechanisms of the reaction and the final properties of the materials. In this work the differences in the final properties of the organic xerogels obtained with basic or acid boosters have been studied. It was found that, irrespective of the nature of the booster, none of the end-product materials showed any differences in their chemical properties. Moreover, the concentrations of the components of the precursor solution (i.e. monomers, water and methanol) were observed to have the same effect on the porous properties of the materials regardless of whether an acidic or a basic booster was used. However, differences in the porous properties were observed. It was found that the methanol content was crucial to tailor the porosity over the entire nanoscale when an acidic booster is used. These results are of great importance as acidic boosters allows to decrease synthesis time and, hence, to produce more competitive materials.

Low‐Cost Carbon Xerogels Derived from Phenol–Formaldehyde Resin for Organic Electric Double‐Layer Capacitors

“…CXs are generally synthesized from condensation of resorcinol and formaldehyde under base catalyst conditions. [37][38][39][40][41][42][43] They have a relatively large surface area due to their textural pores and good conductivity resulting from their 3D carbonparticle structure. Moreover, the physical properties of CXs (such as pore size and pore volume) can be systematically controlled by adjusting the synthesis conditions.…”

“…Moreover, the physical properties of CXs (such as pore size and pore volume) can be systematically controlled by adjusting the synthesis conditions. [19,20,[40][41][42][43] For these reasons, the application of CXs as active materials for EDLC electrodes has been extensively studied. [32][33][34][35][36][37][38][39] However, CXs are not generally used for commercial EDLC electrodes because resorcinol, a compound that is one of the precursors for CXs, is quite expensive.…”

Load-dependent surface diffusion model for analyzing the kinetics of protein adsorption onto mesoporous materials

“…The porous structure of RF xerogels has been extensively reported [44][45][46]51]. The nanostructure of these materials is essentially composed of packed quasi-spherical nodules that can be observed by SEM and TEM [51,52]. The voids between the spheres constitute the porosity of the materials.…”

Hybrid RF-Si Xerogels: A Cost-Effective Proposal for Insulator Materials

“…In addition, to corroborate their chemical composition, Figure 2 shows the representative FT-IR spectrum of each kind of material synthesized. The spectrum for RF xerogel (see Figure 2 a) showed the characteristic bands for these organic materials, which can be assigned as follows: the methylene ether bridges C-O-C (474, 1090, 1217 and 1298 cm −1 ), aliphatic C-H bonds (1459 cm −1 ), aromatic C-H bonds (1511 cm −1 ), aromatic ring stretching vibrations C=C (1610 cm −1 ), C-H stretching vibrations (2930 cm −1 ) and -OH stretching vibrations (3000–3600 cm −1 ) [ 25 , 34 , 35 ]. On the other hand, bands in the Si spectrum (see Figure 2 d) corresponded to those of a silica material synthesized from TEOS: the asymmetric stretching vibration and bending vibrations of Si-O-Si (470, 796 and 1090 cm −1 ), Si-OH bonds (970 and 3400 cm −1 ) and CH2 stretch (1600 cm −1 ) [ 20 , 25 , 28 ].…”