Multifunctional Polymer Nanocomposites Reinforced by 3D Continuous Ceramic Nanofillers

Abstract

Polymer nanocomposites with inclusion of ceramic nanofillers have relatively high yield strength, elastic moduli, and toughness that therefore are widely used as functional coating and films for optoelectronic applications. Although the mechanical properties are enhanced with increasing the fraction of nanofiller inclusion, there generally is an upper limit on the amount of nanofiller inclusion because the aggregation of the fillers in the polymer matrix, which typically occurs, degrades the mechanical and/or optical performances above 5 vol % of inclusions. Here, we demonstrate an unconventional polymer nanocomposite composed of a uniformly distributed three-dimensional (3D) continuous ceramic nanofillers, which allows for extremely high loading (∼19 vol %) in the polymer matrix without any concern of aggregation and loss in transparency. The fabrication strategy involves conformal deposition of AlO nanolayer with a precise control in thickness that ranges from 12 to 84 nm on a 3D nanostructured porous polymer matrix followed by filling the pores with the same type of polymer. The 3D continuous AlO nanolayers embedded in the matrix with extremely high filler rate of 19.17 vol % improve compressive strength by 142% compared to the pure epoxy without AlO filler, and this value is in agreement with theoretically predicted strength through the rule of mixture. These 3D nanocomposites show superb transparency in the visible (>85% at 600 nm) and near-IR (>90% at 1 μm) regions and improved heat dissipation beyond that of conventional AlO dispersed nanocomposites with similar filler loading of 15.11 vol % due to the existence of a continuous thermal conduction path through the oxide network.

Atomic Layer Deposition of Inorganic Thin Films on 3D Polymer Nanonetworks

“…An example of modulating material properties through polymer template-assisted ALD can be found in interpenetrating network composites. Recently, Ahn et al developed a new type of 3D continuous ceramic nanofiller-inserted polymer composite by filling an index-matched polymer in an Al 2 O 3 -coated 3D polymer nanonetwork prepared through the combination of PnP and ALD (Figure 6b) [26]. The content of the ceramic nanofiller, relative to the polymer matrix, can be finely controlled through the ALD cycle.…”

“…In recent years, the potential of ALD based on these benefits has expanded to nanotechnology [7]. As a representative example, ALD has been combined with three-dimensional (3D) polymer nanostructuring methods such as electrospinning, block-copolymer (BCP) lithography [8][9][10][11][12], direct laser writing (DLW) [13][14][15][16][17], multibeam interference lithography (MBIL) [18][19][20], and phase-mask interference lithography (PMIL) [21][22][23][24][25][26][27][28][29][30]. These unconventional nanofabrication techniques specialize in the production of 3D polymer nanonetworks that can serve as templates for subsequent material conversion processes [31].…”

“…Polymer templates have the advantage of being easily removed by thermal treatment, chemical dissolution, or plasma etching, unlike metal or ceramic templates, which require the use of hazardous acid solutions [32]. In polymer template-based strategies, ALD can be used for various purposes, such as (a) modifying the surface of the polymer template from hydrophobic to hydrophilic [23], (b) reducing the porosity of the polymer template [18], (c) adjusting the optical or mechanical properties of the polymer template [14,26], and (d) producing hollow inorganic materials converted from the polymer template [15,16,21,22,27,33].…”

“…Copyright 2011 The Optical Society (OSA)); (e) cross-sectional SEM image of an Al 2 O 3 thin film deposited on a polymer template formed by MBIL (reprinted with permission from[18]. Copyright 2009 The Royal Society of Chemistry); (f) cross-sectional SEM image of an Al 2 O 3 thin film deposited on a polymer template formed by PnP (reprinted with permission from[26]. Copyright 2018 American Chemical Society); (g) cross-sectional SEM and EDS images of a TiO 2 thin film deposited on a polymer template formed by PnP (reprinted with permission from[21].…”

X-ray-Based Spectroscopic Techniques for Characterization of Polymer Nanocomposite Materials at a Molecular Level

“…The use of nanocomposite is not limited to only the improvement of physical properties: unique specific properties are intended to impart for resolving the challenges in certain applications. The formation of fibrous nanocomposites is an interesting and significant example: the combination of different polymers and functional fillers in a nanofibrous form enables organic, inorganic, and their hybrid functional nanofibers that can be applied in a number of applications from biological engineering such as drug delivery [19][20][21][22] and wound healing systems to energy engineering including photovoltaics and batteries [23][24][25][26].…”