Silica Nanoparticle Reinforced Composites as Transparent Elastomeric Damping Materials

Abstract

Inspired by the structure of the cornea, which is the transparent front part of the eye, we developed a transparent and tough silica composite elastomer consisting of poly[di(ethylene glycol)methyl ether methacrylate] (PMEO 2 MA) and 110 nm spherical silica particles without using an organic cross-linking agent. While filler composite elastomers, such as reinforced rubbers, have complex compositions containing multiple additives (dispersants, plasticizers, vulcanizing agents, etc.), the composition of our composite elastomer is very simple. With an increased amount of silica particles, the fracture energy of the composite elastomer (20.2 MJ m −3 ) was improved by 25 times compared to that of unfilled PMEO 2 MA (0.8 MJ m −3 ). Nanoscale mapping using atomic force microscopy elucidated the presence of an interface layer (IL) of approximately 15 nm thickness with a high elastic modulus near the silica particles in the composite elastomer. The fracture energy of the composite elastomer was found to be a maximum when the particle surface distance was approximately 30 nm. This particle surface distance meant that the ILs were just in contact with each other. The surface charge density and Hansen solubility parameter of the silica particles indicated the ionization of silanol groups and interactions caused by hydrogen bonding between polymer chains and the silica surface. The array of silica particles embedded with intervals of a few nanometers was expected to be able to effectively dissipate deformation energy as heat due to shear strain and friction between the particle surface and polymer matrices. Measurements of the vibration-damping properties revealed that the loss factor of the composite elastomer was significantly higher than that of the unfilled elastomer, indicating that the composite elastomer in this study could be applied as an interlayer film for laminated glass in automotive and architectural applications.

Novel Tough and Transparent Ultra-Extensible Nanocomposite Elastomers Based on Poly(2-methoxyethylacrylate) and Their Switching between Plasto-Elasticity and Viscoelasticity

“…An interesting finding was, that in spite of the periodic fluctuations in nanofiller concentration, which were close to the micrometre scale in the extreme case (see Figure 4 b,e further above), no decrease in optical clarity was observed for the low-filled polyMEA/silica elastomers (see Figure 3 further above). This is in contrast with the results obtained for the distantly related nanocomposite based on PMEO2MA-silica (mentioned in Introduction: Asai, Takeoka and co-workers: [ 67 , 68 ]), where filler particles were much larger (110 nm) and where high optical clarity was observed only for highly regular distributions of the filler spheres. In case of polyMEA/nano-SiO 2 studied in this work, the surprising independence of the nanocomposite transparency from fluctuations of filler distribution can be explained by the close match in the refraction indices of filler and matrix: both are given as 1.46 in the literature (amorphous SiO 2 : [ 70 ], polyMEA: [ 71 ]).…”

“…PMEO2MA is a brush polymer structurally related to polyMEA, but with much larger side-chains. The new nanocomposite displayed improved elongation at break values (up to 670% in [ 68 ]), which in a wide range improved with increasing filler amount, except at highest silica loadings. At high silica contents (highly regular arrangement of the spheres), full transparency was achieved in the cornea-inspired material.…”

“…At high silica contents (highly regular arrangement of the spheres), full transparency was achieved in the cornea-inspired material. In [ 68 ], also the role of the interfacial layer and the damping properties of PMEO2MA-silica were investigated. The same group finally also prepared a three-component composite elastomer with PMEO2MA matrix, multilayer graphene (25 µm wide, 6–8 nm thick) as 2D microfiller, and the 110 nm silica spheres [ 69 ].…”

Transparent and Mechanically High-Performance Soft Materials Consisting of Colloidal Building Blocks

“…Let us introduce the inorganic filler composite elastomers with transparency and toughness, which we have been working on. ,, Instead of using inorganic fillers with irregular particle sizes, which are used in conventional inorganic filler composite elastomers, we have tried to achieve both optical transparency and high toughness by introducing silica particles with uniform particle sizes as the inorganic filler. When silica particles with a diameter of 110 nm are dispersed in a liquid with a different refractive index from that of silica, the suspension does not scatter light very much and is colorless and transparent when the amount of silica particles is small (Figure A) .…”

Nanoscale Structures of Poly(oligo ethylene glycol methyl ether methacrylate) Hydrogels Revealed by Small-Angle Neutron Scattering

“…Thus, the volume transition temperature of the copolymerized gels can be controlled from 20 to 90 °C by adjusting the copolymerization ratio between MeO 2 MA and OEGMA during the polymerization. − Moreover, POEGMA chains have many advantages, similar to those of polyethylene glycol chains, such as their nonimmunogenic, noncytotoxic, and protein- (and consequently cell)-repellent properties . Indeed, many studies related to POEGMA-based materials involve their use in advanced biomedical applications, such as bioconjugates, , surface coatings, , particles for carriers, − and injectable gels. − …”