Naturally occurring nanocomposites like nacre owe their exceptional mechanical properties to high loadings of platelets that are bridged by small volume fractions of polymers. Polymer infiltration into dense assemblies of nanoparticles provides a powerful and potentially scalable approach to manufacture bio-inspired nanocomposites that mimic nacre's architecture. Solvent-driven infiltration of polymers (SIP) into nanoparticle packings formed on top of glassy polymer films is induced via capillary condensation of a solvent in the interstitial voids between nanoparticles (NP), followed by plasticization and transport of polymers into the liquid-filled pores, leading to the formation of the nanocomposite structure. To understand the effect of polymer–nanoparticle interactions on the dynamics of polymer infiltration in SIP, we perform molecular dynamics simulations. The mechanism of polymer infiltration and the influence of interactions between polymer and NPs on the dynamics of the process are investigated. Depending on the strength of interaction, polymer infiltration either follows (a) dissolution-dominated infiltration where plasticized polymer chains remain solvated in the pores and rapidly diffuse into the packing or (b) adhesion-dominated transport where the chains adsorb onto the nanoparticle surface and move slowly through the nanoparticle film as a well-defined front. A non-monotonic trend emerges as the adhesion strength is increased; the infiltration of chains becomes faster with the co-operative effect of adhesion and dissolution as adhesion increases but eventually slows down when the polymer–nanoparticle adhesion dominates.
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Polymer-infiltrated nanoplatelet films with nacre-like structure via flow coating and capillary rise infiltration (CaRI)
Alignment of highly anisotropic nanomaterials in a polymer matrix can yield nanocomposites with unique mechanical and transport properties. Conventional methods of nanocomposite film fabrication are not well-suited for manufacturing composites with very high concentrations of anisotropic nanomaterials, potentially limiting the widespread implementation of these useful structures. In this work, we present a scalable approach to fabricate polymer-infiltrated nanoplatelet films (PINFs) based on flow coating and capillary rise infiltration (CaRI) and study the processing–structure–property relationship of these PINFs. We show that films with high aspect ratio (AR) gibbsite (Al (OH) 3 ) nanoplatelets (NPTs) aligned parallel to the substrate can be prepared using a flow coating process. NPTs are highly aligned with a Herman's order parameter of 0.96 and a high packing fraction >80 vol%. Such packings show significantly higher fracture toughness compared to low AR nanoparticle (NP) packings. By depositing NPTs on a polymer film and subsequently annealing the bilayer above the glass transition temperature of the polymer, polymer infiltrates into the tortuous NPT packings though capillarity. We observe larger enhancement in the modulus, hardness and scratch resistance of NPT films upon polymer infiltration compared to NP packings. The excellent mechanical properties of such films benefit from both thermally promoted oxide bridge formation between NPTs as well as polymer infiltration increasing the strength of NPT contacts. Our approach is widely applicable to highly anisotropic nanomaterials and allows the generation of mechanically robust polymer nanocomposite films for a diverse set of applications.
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- Award ID(s):
- 1662695
- NSF-PAR ID:
- 10232439
- Date Published:
- Journal Name:
- Nanoscale
- Volume:
- 13
- Issue:
- 10
- ISSN:
- 2040-3364
- Page Range / eLocation ID:
- 5545 to 5556
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Polymer-infiltrated nanoparticle films (PINFs) are a new class of nanocomposites that offer synergistic properties and functionality derived from unusually high fractions of nanomaterials. Recently, two versatile techniques,capillary rise infiltration (CaRI) and solvent-driven infiltration of polymer (SIP), have been introduced that exploit capillary forces in films of densely packed nanoparticles. In CaRI, a highly loaded PINF is produced by thermally induced wicking of polymer melt into the nanoparticle packing pores. In SIP, exposure of a polymer–nanoparticle bilayer to solvent vapor atmosphere induces capillary condensation of solvent in the pores of nanoparticle packing, leading to infiltration of polymer into the solvent-filled pores. CaRI/SIP PINFs show superior properties compared with polymer nanocomposite films made using traditional methods, including superb mechanical properties, thermal stability, heat transfer, and optical properties. This review discusses fundamental aspects of the infiltration process and highlights potential applications in separations, structural coatings, and polymer upcycling—a process to convert polymer wastes into useful chemicals.more » « less
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Abstract Flexible nanocomposite films, with cobalt ferrite nanoparticles (CFN) as the ferromagnetic component and polyvinylidene fluoride–trifluoroethylene (PVDF-TrFE) copolymer as the ferroelectric matrix, were fabricated using a blade coating technique. Nanocomposite films were prepared using a two-step process; the first process involves the synthesis of cobalt ferrite (CoFe2O4) nanoparticles using a sonochemical method, and then incorporation of various weight percentages (0, 2.5, 5, and 10%) of cobalt ferrite nanoparticles into the PVDF-TrFE to form nanocomposites. The ferroelectric polar
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0NR08691F
