Effects of an Acid Catalyst on the Inorganic Domain of Inorganic−Organic Hybrid Materials

Abstract

New inorganic-organic hybrid coatings have been developed using linseed oil and sunflower oil with the sol-gel precursor tetraethyl orthosilicate (TEOS). Hydrochloric acid (HCl) was used to catalyze the sol-gel reactions. The effects of HCl concentration on the morphology and distribution of the inorganic phase were investigated. Tensile properties, fracture toughness, thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA) of the ceramer coatings were evaluated as a function of acid catalyst concentration. In addition, scanning electron microscopy (SEM) and energy-dispersion X-ray analysis (EDAX) were used to investigate the morphology. The tensile properties showed an optimum acid concentration of 1.0 wt %. The fracture properties indicated that the greatest resistance to crack propagation was obtained with an acid concentration of 0.25 wt %. Thermogravimetric data showed that the thermal stability of the ceramer films increased with increasing acid catalyst. For TEOS/linseed ceramer films, storage modulus and tan δ data suggested that the acid catalyst promoted separation of the inorganic and organic phases. For TEOS/sunflower ceramer films, storage modulus and tan δ data suggested that the HCl promoted dispersion of the organic phase into the rigid inorganic phase.

UV‐Curable Organic‐Inorganic Hybrid Film Coatings Based on Epoxidized Cyclohexene Derivatized Linseed Oil

“…From the results above and previous reports [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]18] about hybrid films, the properties of the hybrid films are TEOS oligomer concentration dependent. However, different systems have different optimum sol-gel precursor contents [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]18] which depend on the chemical structures of the organic and inorganic materials.…”

“…The tand peaks of the hybrid coatings were broad, which indicated that the hybrid materials were inhomogeneous, which has also been reported for other organicinorganic hybrid materials. [4] Figure 4 shows the tensile strength, tensile modulus and strain-at-break as a function of the TEOS oligomer content. The tensile strength (Figure 4a) shows an initial increase in tensile strength from 0 to 5 wt.-% TEOS oligomer, then a large increase from 8.32 MPa to 13.68 MPa (a 160% increase), with a maximum of 14.58 MPa (a 175% increase) obtained at 15 wt.-% TEOS oligomer content.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] However, most of these coatings were thermal cured and not photo-polymerized. As photopolymerization of the organic phase is much faster than the hydrolysis of TEOS, [25] to facilitate a rapid formation of the inorganic network and to avoid volatilization of the TEOS monomers, TEOS oligomers were used instead of monomer.…”

“…Increased tensile strength, hardness and adhesion to metal substrate have previously been reported in hybrid coatings. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]18] Increased tensile strength and hardness have been attributed to the increased crosslink density, which has in turn been attributed to the interaction between the organic and inorganic phase. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]18] Both the ring opening polymerization of epoxidized cyclohexene derivatized linseed oil (ECLO) and the sol-gel reactions of TEOS oligomers were acid catalyzed, resulting in cocomitant curing of both the organic and inorganic phases.…”

A Study of Cyclohexane Diffusion in Hybrid (Organic/Inorganic) Gels Monitored by an Oscillating Balance Reactor

“…In brief, a cyclic oligosiloxane, [(CH 3 ) 2 Si-O] 4 , and tetraethylorthosilicate (TEOS, (OEt) 4 Si) at a 0.25 : 2 molar ratio were cohydrolyzed/cocondensed in the presence of a substoichiometric amount of water at 333 K for 6 h. Subsequently, TiCI 2 (iPrO) 2 was added to produce a solid (after 24 h) with about 2.5 wt% Ti. This material has already been used as an effective olefin epoxidation catalyst in our group (3 2 Si-O∼ reactive monomers during hydrolysis.…”