Novel Percolation Mechanism in PMMA Matrix Composites Containing Segregated ITO Nanowire Networks

Abstract

Poly(methyl methacrylate) (PMMA)/indium tin oxide (ITO) nanocomposites were prepared by mechanical mixing and compression molding in order to study the properties and microstructure of the composites. The composites were examined by optical and scanning electron microscopy, impedance spectroscopy, and UV‐VIS spectrophotometry. It was observed that upon compaction of the powders above the glass‐transition temperature of the matrix, the PMMA transforms from spherical to polyhedral‐shaped, and develops sharp edges and flat faces. The ITO nanoparticles do not penetrate the polymer particles, resulting in a novel segregated network microstructure. Excellent correlation between the electrical, optical, and microscopy data also provide good insight about the behavior of the filler as the content is increased in the nanocomposites. There is strong evidence that the ITO nanoparticles are extensively displaced during compaction as the PMMA powders become polyhedral‐shaped. Our results indicate that percolation occurs due to the ITO forming a continuous network along the edges of the faceted PMMA particles. The ITO nanoparticles do not appear on the faces of the PMMA particles until after a percolation path has formed and a marked increase in electrical conductivity has occurred. This behavior significantly diverges from previous models for segregated network microstructures which proposed that percolation occurred as the result of limited displacement of the filler during compaction of the mixed powders.

Fabrication and simulation of semi-transparent and flexible PMMA/ATO conductive nanocomposites obtained by compression molding at different temperatures and pressures

“…The PMMA and ATO particles were mechanically blended for 10 min in a blender at room temperature as has been described in our previous papers. 1,8 The surface of the polymer matrix was uniformly covered by the ATO nanoparticles (NPs) during mechanical blending. However, localized heating in the blender should be avoided, because partial melting of the polymer spheres can decrease the connectivity of the filler-chain network during compression molding.…”

“…[1][2][3] Many processing techniques such as melt blending, 4 solution blending, 4,5 in-situ polymerization, 6 latex blending 7 and mechanical blending 1,8,9 have been used to fabricate polymer matrix conductive composites.…”

“…obtaining electrical percolation at low concentration of fillers. 1,8,9 The final electrical conductivity can be a Electronic mail: rosario.gerhardt@mse.gatech.edu. tunable by using fillers with different electrical conductivity, because this fabrication method provides ordered phase segregated filler networks, regardless of filler types.…”

Effects of crystallization on the optical properties of ZnO nano-pillar thin films by sol-gel method

“…Many one dimensional (1D) nanostructures, such as ZnO [1,2], In 2 O 3 [3], SnO 2 [4], ITO [5] and TiO 2 [6] have attracted great attention in recent years due to their potential applications in electronics and optoelectronic devices. One of the prominent metal-oxide materials, ZnO has been intensely studied for potential applications in electronics, optoelectronics and piezoelectricity [7].…”

Influence of Stabilizer Concentration on Transport Behavior and Thermopower of CNT‐Filled Latex‐Based Composites

“…Segregated network polymer composites are well suited for tailoring transport properties because they are very sensitive to filler properties, concentration, and interactions. [23][24][25][26][27] These composites are often made with a polymer emulsion (or latex), [28][29][30][31][32] which is a suspension of polymer particles in water. [33] When mixed with CNTs, the relatively large polymer particles (100 nmÀ1 mm) push the smaller CNTs into the interstitial space between them during drying, as illustrated in Scheme 1.…”