Tag Archive for: deposition

Scientific publication

Demonstrating a Quartz Crystal Microbalance with Dissipation (QCMD) to Enhance the Monitoring and Mechanistic Understanding of Iron Carbonate Crystalline Films

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Authors: Igor Efimov, Eftychios Hadjittofis, Mustafa M. Alsalem, and Kyra L. Sedransk Campbell

Journal: Langmuir

Abstract:

This paper reports the real time monitoring of siderite deposition, on both Au- and Fe-coated surfaces, using the changes in frequency and dissipation of quartz crystal microbalance with dissipation (QCMD). In an iron chloride solution saturated with carbon dioxide, buffered with sodium bicarbonate to pH 6.8, roughly spherical particles of siderite formed within 15 min, which subsequently deposited on the QCMD crystal surface. Imaging of the surface showed a layer formed from particles ca. < 0.5 μm in diameter. Larger particles are clearly deposited on top of the lower layer; these larger particles are >1 μm in diameter. Monitoring of the frequency clearly differentiates the formation of the lower layer from the larger crystals deposited on top at later times. The elastic moduli calculated from QCMD data showed a progressive dissipation increase; the modeling of the solid–liquid interface using a flat approximation resulted in a poor estimation of elastic and storage moduli. Rather, the impedance modeled as a viscoelastic layer in contact with a semi-infinite liquid, where a random bumpy surface with a Gaussian correlator is used, is much more accurate in determining the elastic and storage moduli as losses from the uneven interface are considered. A further step considers that the film is in fact a composite consisting of hard spherical particles of siderite with water in the vacant spaces. This is treated by considering the individual contributions of the phases to the losses measured, thereby further improving the accuracy of the description of the film and the QCMD data. Collectively, this work presents a new framework for the use of QCMD, paired with traditional approaches, to enhance the understanding of crystal deposition and film formation as well as quantify the often evolving mechanical properties.

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Publication on AWSensors technology

Nanoporous Metal–Organic Framework Thin Films Prepared Directly from Gaseous Precursors by Atomic and Molecular Layer Deposition: Implications for Microelectronics

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Authors: Jenna Multia, Dmitry E. Kravchenko, Víctor Rubio-Giménez, Anish Philip, Rob Ameloot, and Maarit Karppinen

Journal: ACS Appl. Nano Mater. (2023)

 

Abstract

Atomic/molecular layer deposition (ALD/MLD) allows for the direct gas-phase synthesis of crystalline metal–organic framework (MOF) thin films. Here, we show for the first time using krypton and methanol physisorption measurements that ALD/MLD-fabricated copper 1,4-benzenedicarboxylate (Cu-BDC) ultrathin films possess accessible porosity matching that of the corresponding bulk MOF.

 

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Publication on AWSensors technology

Aerosol Jet Printing of the Ultramicroporous Calcium Squarate Metal–Organic Framework

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Authors: Dmitry E. Kravchenko, Aleksander Matavž, Víctor Rubio-Giménez, Hanne Vanduffel, Margot Verstreken, Rob Ameloot

Journal: Chem. Mater. (2022)

 

Abstract

Efficient methods to deposit thin layers of metal–organic frameworks (MOFs) are needed to integrate these microporous materials into microelectronics, sensing devices, and membranes. Herein, we report for the first time the direct aerosol jet printing of a MOF material. The ultramicroporous MOF [Ca(C4O4) (H2O)] (UTSA-280) was deposited from an aqueous precursor solution. In addition to blanket coatings, aerosol jet printing provides direct access to patterned coatings with a resolution of 100 μm via a digital, maskless approach. Moreover, by enabling spatial control over the layer thickness via the number of passes of the nozzle, this direct-write approach presents a more accessible alternative to advanced patterning techniques such as grayscale lithography.

 

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pH Controlled Electrochemical Deposition of Polyelectrolyte Complex Films

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Authors: Kazi Sadman, Qifeng Wang, Shawn H Chen, David Efim Delgado and Kenneth R Shull. Northwestern University, Evanston, Illinois, US

Journal:  Langmuir 2017, 33(8) 1834-1844.

Abstract: Polyelectrolyte complex (PEC) films made from oppositely charged polymer chains have applications as drug delivery vehicles, separation membranes, and biocompatible coatings. Conventional layer-by-layer (LbL) techniques for polyelectrolyte coatings are low-throughput and multistep processes that are quite slow for building films on the order of micrometers. In this work, PEC films are electrochemically deposited using a rapid one-pot method yielding thick (1 μm) films within short experimental time scales (5 min). This rapid electrodeposition is achieved by exploiting the reduction of hydrogen peroxide at mild electrode potentials that avoid water electrolysis, yet trigger the pH responsive self-assembly of a PEC film composed of poly(acrylic) acid and poly (allylamine) HCl. In-situ rheology using an electrochemical quartz crystal microbalance (EQCM) quantified the shear modulus-density product of the deposited layer to be on the order of 107 Pa-g/cm3 at a frequency of 15 MHz, with a viscoelastic phase angle at this frequency of approximately 50○. This electrodeposition scheme furthers the development of PEC coatings for more high-throughput applications where a fast and efficient single step approach would be desirable for obtaining coatings.

Link: https://doi.org/10.1021/acs.langmuir.6b04491