@misc{parsons_atanasov_dandley_devine_gong_jur_lee_oldham_peng_spagnola_et al._2013, title={Mechanisms and reactions during atomic layer deposition on polymers}, volume={257}, ISSN={["1873-3840"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000327915000012&KeyUID=WOS:000327915000012}, DOI={10.1016/j.ccr.2013.07.001}, abstractNote={There is significant growing interest in atomic layer deposition onto polymers for barrier coatings, nanoscale templates, surface modification layers and other applications. The ability to control the reaction between ALD precursors and polymers opens new opportunities in ALD materials processing. It is well recognized that ALD on many polymers involves subsurface precursor diffusion and reaction which are not encountered during ALD on solid surfaces. This article reviews recent insights into chemical reactions that proceed during ALD on polymers, with particular focus on the common Al2O3 reaction sequence using trimethyl aluminum (TMA) and water. We highlight the role of different polymer reactive groups in film growth, and how the balance between precursor diffusion and reaction can change as deposition proceeds. As a strong Lewis acid, TMA forms adducts with Lewis base sites within the polymer, and the reactions that proceed are determined by the neighboring bond structure. Moreover, the Lewis base sites can be saturated by TMA, producing a self-limiting half-reaction within a three-dimensional polymer, analogous to a self-limiting half-reaction commonly observed during ALD on a solid planar surface.}, number={23-24}, journal={COORDINATION CHEMISTRY REVIEWS}, author={Parsons, Gregory N. and Atanasov, Sarah E. and Dandley, Erinn C. and Devine, Christina K. and Gong, Bo and Jur, Jesse S. and Lee, Kyoungmi and Oldham, Christopher J. and Peng, Qing and Spagnola, Joseph C. and et al.}, year={2013}, month={Dec}, pages={3323–3331} }
 @article{gong_spagnola_arvidson_khan_parsons_2012, title={Directed inorganic modification of bi-component polymer fibers by selective vapor reaction and atomic layer deposition}, volume={53}, ISSN={["1873-2291"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000309377400009&KeyUID=WOS:000309377400009}, DOI={10.1016/j.polymer.2012.08.018}, abstractNote={Abstract Nanocomposite organic/inorganic materials with spatially-controlled composition can be formed using vapor-phase atomic layer deposition (ALD) on bi-component polymer fibers. The ALD process promotes selective precursor infusion into the inner core of a core/shell polymer fiber, yielding nanoparticles encapsulated within the core. Likewise, choosing alternate precursors or reaction conditions yield particles or films on the outer polymer shell. In-situ infrared spectroscopy and transmission electron microscopy show that infusion yields selective dispersion of aluminum oxide in different polymer regions, forming fine nanoparticle dispersions or films. Selective inclusion of metal oxide materials during atomic layer deposition on polymers can create unique organic/inorganic composite structures for many advanced uses.}, number={21}, journal={POLYMER}, author={Gong, Bo and Spagnola, Joseph C. and Arvidson, Sara A. and Khan, Saad A. and Parsons, Gregory N.}, year={2012}, month={Sep}, pages={4631–4636} }
 @article{gong_spagnola_parsons_2012, title={Hydrophilic mechanical buffer layers and stable hydrophilic finishes on polydimethylsiloxane using combined sequential vapor infiltration and atomic/molecular layer deposition}, volume={30}, ISSN={["0734-2101"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000298992800056&KeyUID=WOS:000298992800056}, DOI={10.1116/1.3670963}, abstractNote={Polydimethylsiloxane (PDMS) is an important polymer material widely used for microfluidic device fabrication, microcontact lithography, and surface morphology molding. However, the hydrophobic surface limits its functionality. Low temperature atomic layer deposition (ALD) has recently been used to functionalize a wide range of polymer surfaces. In previous research, the authors were able to produce a uniform hydrophilic alumina film coating on PDMS using trimethyl aluminum/water ALD. However, the surface recovered its hydrophobicity after 24–48 h in ambient air or under inert gas storage, which was ascribed to organic species outdiffusion through the ALD layer. This paper reports a stable hydrophilic ALD surface modification on the PDMS. The PDMS substrate was first sequentially exposed to trimethylaluminum and water vapor, allowing the vapors to infiltrate and react to create a mechanical and diffusion buffer layer in the PDMS surface region. This buffer layer helps to nucleate a cohesive hydrophilic ALD or molecular layer deposition (MLD) coating and also helps prevent organic outdiffusion that typically leads to PDMS hydrophobic recovery. The results provide valuable insight into reliable surface energy and mechanical modification of PDMS using vapor-phase precursor/polymer reactions. In addition, molecular layer deposition of “alucone” coatings was also investigated to modify the PDMS surface. The experiment result showed the vapor infiltration and MLD coatings produce a viable and stable hydrophilic surface on PDMS.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Gong, Bo and Spagnola, Joseph C. and Parsons, Gregory N.}, year={2012}, month={Jan} }
 @article{oldham_gong_spagnola_jur_senecal_godfrey_parsons_2011, title={Encapsulation and Chemical Resistance of Electrospun Nylon Nanofibers Coated Using Integrated Atomic and Molecular Layer Deposition}, volume={158}, ISSN={["1945-7111"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000293175600039&KeyUID=WOS:000293175600039}, DOI={10.1149/1.3609046}, abstractNote={Nanofibers formed by electrospinning provide very large surface areas which can enhance material performance in filtration and product separation. In this work, we explore atomic layer deposition (ALD) as a means to coat and protect electrospun nylon-6 nanofibers. Exposing nylon to trimethyl aluminum (TMA) during ALD of aluminum oxide results in significant fiber degradation. Protecting fibers with a bilayer of ALD ZnO and an organic-inorganic hybrid polymer by molecular layer deposition maintains the shape of the original nanofibers, but chemical modification is still detected. These coating processes may help enable nanofibers with stable physical properties under chemical exposure.}, number={9}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Oldham, Christopher J. and Gong, Bo and Spagnola, Joseph C. and Jur, Jesse S. and Senecal, Kris J. and Godfrey, Thomas A. and Parsons, Gregory N.}, year={2011}, pages={D549–D556} }
 @article{spagnola_gong_arvidson_jur_khan_parsons_2010, title={Surface and sub-surface reactions during low temperature aluminium oxide atomic layer deposition on fiber-forming polymers}, volume={20}, ISSN={["0959-9428"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000277563800026&KeyUID=WOS:000277563800026}, DOI={10.1039/c0jm00355g}, abstractNote={Fundamental reaction processes between vapor-phase chemical precursors and high molecular weight polymers are important for polymer coating, encapsulation and surface modification. Using trimethylaluminium and water in an atomic layer deposition (ALD) exposure sequence, reactions between vapor-phase trimethylaluminium and common polymers with different substituents are quantified using in situ infrared transmission analysis. Exposing polypropylene to trimethylaluminium results in reactant uptake with minimal precursor/polymer reaction, but the precursor/water ALD sequence leads to subsurface alumina nucleation. A similar treatment to polyvinyl alcohol and polyamide-6 results in rapid precursor diffusion and significant reaction observed by IR, and the extent of reaction is consistent with results from in situ quartz crystal microgravimetry and transmission electron microscopy. Reacting trimethylaluminium with polyamide-6 leads to methyl group insertion into the amide carbonyl group and interaction with the hydrogen-bonded amine units. Multiple ALD reaction cycles produce film coatings on all polymers studied, but the coating structure depends strongly on the starting polymer composition. For the weakly interacting polypropylene, cross-sectional transmission electron microscopy demonstrates enhanced sub-surface growth at 90 °C as compared to that at 60 °C, while images of coated polyamide-6 fibers showed that growth is not strongly temperature dependent in that range. Micrograph images of polyamide-6 samples exposed to extended TMA doses revealed significant modification of the fiber surface region, demonstrating that the precursor could diffuse and react to depths in excess of 100 nm into the surface of the polymer at 90 °C. Improved understanding of specific precursor/polymer reaction pathways can be important to optimize the performance of conformal inorganic thin film coatings on polymers.}, number={20}, journal={JOURNAL OF MATERIALS CHEMISTRY}, author={Spagnola, Joseph C. and Gong, Bo and Arvidson, Sara A. and Jur, Jesse S. and Khan, Saad A. and Parsons, Gregory N.}, year={2010}, pages={4213–4222} }
 @article{jur_spagnola_lee_gong_peng_parsons_2010, title={Temperature-Dependent Subsurface Growth during Atomic Layer Deposition on Polypropylene and Cellulose Fibers}, volume={26}, ISSN={["0743-7463"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000277928100078&KeyUID=WOS:000277928100078}, DOI={10.1021/la904604z}, abstractNote={Nucleation and subsequent growth of aluminum oxide by atomic layer deposition (ALD) on polypropylene fiber substrates is strongly dependent on processing temperature and polymer backbone structure. Deposition on cellulose cotton, which contains ample hydroxyl sites for ALD nucleation and growth on the polymer backbone, readily produces a uniform and conformal coating. However, similar ALD processing on polypropylene, which contains no readily available active sites for growth initiation, results in a graded and intermixed polymer/inorganic interface layer. The structure of the polymer/inorganic layer depends strongly on the process temperature, where lower temperature (60 degrees C) produced a more abrupt transition. Cross-sectional transmission electron microscopy images of polypropylene fibers coated at higher temperature (90 degrees C) show that non-coalesced particles form in the near-surface region of the polymer, and the particles grow in size and coalesce into a film as the number of ALD cycles increases. Quartz crystal microbalance analysis on polypropylene films confirms enhanced mass uptake at higher processing temperatures, and X-ray photoelectron spectroscopy data also confirm heterogeneous mixing between the aluminum oxide and the polypropylene during deposition at higher temperatures. The strong temperature dependence of film nucleation and subsurface growth is ascribed to a relatively large increase in bulk species diffusivity that occurs upon the temperature-driven free volume expansion of the polypropylene. These results provide helpful insight into mechanisms for controlled organic/inorganic thin film and fiber materials integration.}, number={11}, journal={LANGMUIR}, author={Jur, Jesse S. and Spagnola, Joseph C. and Lee, Kyoungmi and Gong, Bo and Peng, Qing and Parsons, Gregory N.}, year={2010}, month={Jun}, pages={8239–8244} }
 @article{peng_sun_spagnola_saquing_khan_spontak_parsons_2009, title={Bi-directional Kirkendall Effect in Coaxial Microtuble Nanolaminate Assemblies Fabricated by Atomic Layer Deposition}, volume={3}, ISSN={["1936-086X"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000264535200010&KeyUID=WOS:000264535200010}, DOI={10.1021/nn8006543}, abstractNote={The solid-state reaction within a coaxial Al2O3/ZnO/Al2O3 multilayered microtubular structure can be used to prepare discrete microtube-in-microtube ZnAl2O4 spinel assemblies through a Kirkendall void production mechanism at 700 degrees C. In contrast with previous studies of the nanoscale Kirkendall effect, the reaction observed here proceeds through a bi-directional vacancy diffusion mechanism wherein ZnO species diffuse into inner- and outer-Al2O3 concentric layers, thereby resulting in vacancy supersaturation and void production between two isolated spinel microtubes. Low-temperature atomic layer deposition (ALD) of Al2O3 and ZnO enables the fabrication of complex coaxial multilayered microtubes with precise control of the starting film thicknesses and relative composition. When a molar excess of ZnO is present between two Al2O3 layers, electron microscopy images reveal incomplete ZnO consumption after annealing at 700 degrees C. At higher initial Al2O3 concentrations, however, complete reaction with ZnO is observed, and the size of the Kirkendall gap between isolated spinel microtubes appears to be directly influenced by the thickness of the intermediate ZnO layer.}, number={3}, journal={ACS NANO}, author={Peng, Qing and Sun, Xiao-Yu and Spagnola, Joseph C. and Saquing, Carl and Khan, Saad A. and Spontak, Richard J. and Parsons, Gregory N.}, year={2009}, month={Mar}, pages={546–554} }
 @article{peng_spagnola_daisuke_park_parsons_2008, title={Conformal metal oxide coatings on nanotubes by direct low temperature metal-organic pyrolysis in supercritical carbon dioxide}, volume={26}, ISSN={["2166-2746"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000256304600016&KeyUID=WOS:000256304600016}, DOI={10.1116/1.2917072}, abstractNote={The authors demonstrate that low temperature (<200 °C) thermal decomposition of metal-organic precursors dissolved in supercritical carbon dioxide (scCO2) is an effective method to penetrate into dense three-dimensional networks and deposit conformal metal oxide films with tunable thickness. The results specifically show that thermal decomposition of gallium acetylacetonate in scCO2, leads to conformal coatings of gallium oxide on multiwalled carbon nanotube forests with a fast deposition rate (∼3–4 nm/min), without the need for any cosolvent. Moreover, as-formed metal oxide/nanotube structures can be further conformally coated by metal atomic layer deposition to produce nanotube/oxide/metal nanocomposites.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Peng, Qing and Spagnola, Joseph C. and Daisuke, Hojo and Park, Kie Jin and Parsons, Gregory N.}, year={2008}, month={May}, pages={978–982} }
 @article{peng_spagnola_parsons_2008, title={Self-catalyzed hydrogenolysis of nickelocene: Functional metal coating of three-dimensional nanosystems at low temperature}, volume={155}, ISSN={["0013-4651"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000258038800037&KeyUID=WOS:000258038800037}, DOI={10.1149/1.2946723}, abstractNote={In this paper we demonstrate the hydrogenolysis of nickelocene can take place through a self-catalyzed process at low temperature (<70°C) in supercritical carbon dioxide to generate relatively uniform dispersed Ni (nickel) metal particles onto carbon nanotubes forests and Ni films on flat surfaces. The ability to form metal particles or films without a local catalyst at this low temperature is significant because it provides further insight into mechanisms for Ni deposition reactions, and it enables a new route for low-temperature metal coating on a range of nonmetal substrate materials with complex topographies and nanostructures, for example, to form Ni/polymer magnetic nanocomposites.}, number={9}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Peng, Qing and Spagnola, Joseph C. and Parsons, Gregory N.}, year={2008}, pages={D580–D582} }
 @article{peng_sun_spagnola_hyde_spontak_parsons_2007, title={Atomic layer deposition on electrospun polymer fibers as a direct route to Al2O3 microtubes with precise wall thickness control}, volume={7}, ISSN={["1530-6984"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000244867400032&KeyUID=WOS:000244867400032}, DOI={10.1021/nl062948i}, abstractNote={Atomic layer deposition (ALD) of Al2O3 on electrospun poly(vinyl alcohol) microfiber templates is demonstrated as an effective and robust strategy by which to fabricate long and uniform metal-oxide microtubes. The wall thickness is shown to be precisely controlled within a molecular layer or so by adjusting the number of ALD cycles utilized. By judicious selection of the electrospinning and ALD parameters, designer tubes of various sizes and inorganic materials can be synthesized.}, number={3}, journal={NANO LETTERS}, author={Peng, Qing and Sun, Xiao-Yu and Spagnola, Joseph C. and Hyde, G. Kevin and Spontak, Richard J. and Parsons, Gregory N.}, year={2007}, month={Mar}, pages={719–722} }