Silica Coating of Nonsilicate Nanoparticles for Resin-Based Composite Materials

Abstract

A supplemental appendix to this article is published electronically only at http://jdr.sagepub.com/supplemental. AbstractThis study was designed to develop and characterize a silica-coating method for crystalline nonsilicate ceramic nanoparticles (Al 2 O 3 , TiO 2 , and ZrO 2 ). The hypothesis was that the coated nonsilicate nanoparticles would stably reinforce a polymeric matrix due to effective silanation. Silica coating was applied via a sol-gel method, with tetraethyl orthosilicate as a silica precursor, followed by heat treatment. The chemical and microstructural characteristics of the nanopowders were evaluated before and after silica coating through x-ray diffraction, BET (Brunauer-Emmett-Teller), energy-dispersive x-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy analyses. Coated and noncoated nanoparticles were silanated before preparation of hybrid composites, which contained glass microparticles in addition to the nanoparticles. The composites were mechanically tested in 4-point bending mode after aging (10,000 thermal cycles). Results of all chemical and microstructural analyses confirmed the successful obtaining of silica-coated nanoparticles. Two distinct aspects were observed depending on the type of nanoparticle tested: 1) formation of a silica shell on the surface of the particles and 2) nanoparticle clusters embedded into a silica matrix. The aged hybrid composites formulated with the coated nanoparticles showed improved flexural strength (10% to 30% higher) and work of fracture (35% to 40% higher) as compared with composites formulated with noncoated nanoparticles. The tested hypothesis was confirmed: silanated silica-coated nonsilicate nanoparticles yielded stable reinforcement of dimethacrylate polymeric matrix due to effective silanation. The silica-coating method presented here is a versatile and promising novel strategy for the use of crystalline nonsilicate ceramics as a reinforcing phase of polymeric composite biomaterials.

Characterization of Bis-Acryl Composite Resins for Provisional Restorations

“…A previous study (7) revealed that crack propagation within bis-acryl provisional materials occur primarily through the polymer matrix between filler particles. The long-term interaction between inorganic fillers is also a factor affecting the mechanical performance of resin-based composites (19). Water sorption and swelling effects may consequently interfere with the overall polymer strength.…”

Functionalized pink Al 2 O 3 :Mn pigments applied in prosthetic dentistry

“…Previously published results of elemental mapping by EDS/SEM show a thin film of Si atoms on the surface of the alumina particles, 36 so the silica layer is not expected to significantly affect particle size. In addition, its presence allows for effective and stable silanation, 34 which is required for a strong bond between resin matrix and filler particles, and avoids interfacial pores that would compromise not only the mechanical properties of the composite resins 18–20 but also their translucency. 22–24 In the present study though, the chemical interaction of silane with the silica coated pigment particles and with the PMMA matrix was not investigated.…”

“…30,31 The hydrolytic degradation of the polymeric matrix can lead to filler/pigment particle loss and/or degradation. 26,32 Therefore, the use of functionalized well-bonded pigment particles 33,34 could provide significant improvements. These include elimination of the porosity associated with nonbonded particles, reducing sorption of extrinsic staining agents and particle loss due to abrasion and the possibility of using a greater maximum quantity of inorganic pigment, thereby reducing or eliminating the need for organic pigments.…”

Properties of multifunctional composite materials based on nanomaterials: a review

“…Kaizer et al 37 have reported an improvement in both the modulus and longitudinal compressive strength, which was obtained by adding silica based nano particles in epoxy. The problem with the addition of silica particles was the presence of equal-distribution of silica particles among the polymer matrix, which was achieved by the sol-gel process.…”

“…However, there was no impact on the concentration of micron size particles. 37 Studies on the addition of MWCNTs in epoxy for composite materials have shown greater improvements in the fracture toughness, strength, and other mechanical properties. [38][39][40] Gallego et al 38 have compared the mechanical properties and ller percolation in multifunctional nano-composite.…”