Mechanical Properties of Soluble Polymer/Silica Gel Hybrids

Abstract

Strengths have been measured for silica gels prepared with poly(ethylene oxide) (PEO) and poly(vinyl acetate) (PVAc). The modulus of rupture was determined using standard three-point bending in a mechanical tester. The samples were prepared by mixing tetraethylorthosilicate with the polymers dissolved in water (PEO) or water/ethanol(PVAc). Molecular weights between 200 and 3400 were used for PEO. Substitutions of the polymer for silica represented between 5 and 25% on a weight basis. In these systems, the interactions between the polymer and the silica network are largely through hydrogen bonding, between ether oxygens in PEO and silanols and between hydroxyls in PVAc and silanols. The extent of the bonding increases with increasing aging time, as indicated by an almost linear increase in the modulus of rupture. The increase for PEO was greater than for PVAc. Among PEO samples, the strengths were higher for higher molecular weights at the same weight fraction.

Molecular Simulation Study of Polymer Interactions with Silica Particles in Aqueous Solution

“…One of the properties of OIPH materialsincreased hardness while retaining flexibilitymakes them valuable in a wide range of applications, particularly in coatings. , This property is due to complementary contributions from the inorganic component (silica), which adds hardness to the resultant product, and from the polymeric component, which adds flexibility. − Several hypotheses have been suggested to explain the molecular mechanisms of formation of the hybrid materials, based primarily on experimental measurements during various stages of the sol−gel process, the common method for preparation of inorganic amorphous solids. , …”

“…1,2 This property is due to complementary contributions from the inorganic component (silica), which adds hardness to the resultant product, and from the polymeric component, which adds flexibility. [3][4][5][6][7] Several hypotheses have been suggested to explain the molecular mechanisms of formation of the hybrid materials, based primarily on experimental measurements during various stages of the sol-gel process, the common method for preparation of inorganic amorphous solids. 3,4 Investigations of the synthesis of aqueous sol-gel systems include the work by Schmidt et al, 1 which involved the preparation of coating precursors that are soluble in water, by modifying commercially available sols with alkoxysilanes (reducing the particle to particle interaction), to fabricate an aqueous sol-gel coating material.…”

“…[3][4][5][6][7] Several hypotheses have been suggested to explain the molecular mechanisms of formation of the hybrid materials, based primarily on experimental measurements during various stages of the sol-gel process, the common method for preparation of inorganic amorphous solids. 3,4 Investigations of the synthesis of aqueous sol-gel systems include the work by Schmidt et al, 1 which involved the preparation of coating precursors that are soluble in water, by modifying commercially available sols with alkoxysilanes (reducing the particle to particle interaction), to fabricate an aqueous sol-gel coating material. It was found that the water stability of these coating materials is comparable to the alcoholbased systems and the process can be used to incorporate other nanoparticles such as titania or alumina.…”

“…A further example of investigations into synthesis of physical hybrids include the work performed by Klein et al 3 which examined the mechanical properties of hybrids created via the sol-gel method. Samples containing poly(ethyleneoxide) (PEO) or poly(vinyl acetate) (PVAc) were prepared by mixing tetraethyl orthosilicate with water or a water/ethanol mixture.…”