Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session Y04: Physics of Soft Materials Advanced Manufacturing II: Photopolymers, Fibers, and Films |
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Sponsoring Units: DPOLY Chair: Kenan Song, Arizona State University Room: Room 127 |
Friday, March 10, 2023 8:00AM - 8:12AM |
Y04.00001: Ultra-Low-Frequency Longitudinal Acoustic Phonon Modes Provide Insight into Polymerization Kinetics of Epoxy and Dual-Cure Resins Robert V Chimenti, Alexandra M Lehman-Chong, Jianwei Tu, James T Carriere, Alyssa M Sepcic, Joseph F Stanzione, Samuel Lofland In resin-based additive manufacturing, the extent of cure influences the printability and fidelity of the final product. This process has generally been monitored with infrared spectroscopy to compare conversion-sensitive bands to a reference band, but the approach cannot be used for in-situ measurements. On the other hand, Raman spectroscopy, which complements infrared, is ideal for in-situ measurement and has recently become readily accessible for use in applied studies. In addition to the chemical vibrational bands, the Raman spectrum of polymers has an additional peak at ~10–20 cm-1 due to the amorphous structure. This feature, also known as the Boson peak, arises due to longitudinal acoustic phonon modes (LAMs) which are directly related to the phonon density of states. Utilizing the LAMs, we have developed a "chemically agnostic" method to monitor polymerization kinetics with much better signal-to-noise than traditionally possible. This technique is particularly useful for in-situ studies of epoxy-based resins as the opening of the epoxy ring is extremely difficult to monitor with vibrational spectroscopy. Finally, we demonstrate the detection of transient structural changes during the curing process by monitoring both the Stokes and anti-Stokes lines of the LAMs. |
Friday, March 10, 2023 8:12AM - 8:24AM |
Y04.00002: Photobase Initiated Network Formation for Two-Photon Polymerization Madelyn P Jeske, David R Harding, Mitchell Anthamatten, Aofei Mao, Xi Huang, Yongfeng Lu Additive manufacturing of high resolution, responsive soft materials is highly desired for applications including robotics, cellular scaffolds, and responsive metamatierals. Two-photon polymerization (2PP) is a form of direct laser writing whereby a pulsed, femtosecond laser is tightly focused onto three dimensional volume element (voxel) within a droplet of resin to locally initiate polymerization. The pulsed beam is translated over a designated path to polymerize customized, three-dimensional structures with feature lengths well below a micron. We demonstrate that a photobase generator within a mixture of multifunctional thiol and multifunctional acrylate monomers can lead to rapid formation of a molecular network. Spectroscopic analysis establishes how the degree of chemical conversion depends on laser dose. Our results open up new pathways to develop 2PP resins for printing high-resolution microstructures with improved conversion, mechanical properties, and reduced shrinkage. |
Friday, March 10, 2023 8:24AM - 8:36AM |
Y04.00003: Computational reaction networks applied to reaction cascades in EUV lithography Samuel M Blau, Eric Sivonxay, Brett Helms, Frances A Houle, Patrick Naulleau Next-generation semiconductor manufacturing achieving sub-10nm feature sizes requires highly precise lithographic patterning with extreme ultraviolet (EUV) light. However, EUV exposure of polymeric photoresists drives a reaction cascade via photoionization and low-energy electron attachment which remains poorly understood, limiting spatial control and pattern resolution. Chemical reaction networks (CRNs) are powerful tools for obtaining insight into complex reactive processes. However, they are difficult to employ when reaction mechanisms and products are not thoroughly understood. Here we describe new methods of CRN generation and analysis that seek to overcome these limitations. We combine high-throughput density functional theory calculations, numerical analysis, and machine learning to tractably build up CRNs from only starting species, predicting possible cascade products and their formation pathways. We apply this methodology to study secondary-electron-driven reactivity in EUV lithography and present preliminary results. |
Friday, March 10, 2023 8:36AM - 8:48AM |
Y04.00004: Atomistic modeling approach for predicting association of ionic salts in extreme ultraviolet polymeric photoresists Prajwal Bangalore, Fernando A Escobedo Extreme Ultraviolet (EUV) lithography has proven to be a promising tool to achieve sub-10nm device features. EUV photoresists are a complex blend of components involving ionic photoacid generator (PAG) and quencher salts in an acid-sensitive polymer. We employed atomistic molecular dynamics simulations to probe the effect of ionic and steric interactions on the dispersibility of PAGs in the polymer medium before EUV exposure, as poor dispersibility is a potential source of post-exposure feature roughness. We chose as model PAGs Triphenyl sulfonium (TPS) cation with triflate and adamantlytetrafluoroethyl sulfonate anions, and as photoresists poly(tert-butyl methacrylate) (PtBMA) and poly(4-hydroxy styrene) (PHS) homopolymers and copolymers. We calculated the potential of mean force (PMF) for the dissociation of PAGs at infinite dilution in different polymers. Our results indicate that PHS segments provide a better solvation environment for the PAGs than the PtBMA segments and the triflate PAG solvates better than the bulky TPS-adamantlytetrafluoroethyl sulfonate salt. Local nanostructural signatures (like the extent of hydrogen bonding) and high PAG concentration (up to 28% wt.) simulations confirm that a higher tendency of PAG association correlates with a higher PMF dissociation barrier at infinite dilution, underlining the latter's predictive potential. |
Friday, March 10, 2023 8:48AM - 9:00AM |
Y04.00005: Rheology and Spinnability of Polyvinylpyrrolidone Solutions Louie Edano, Cheryl L Slykas, Vihar Trada, Carina Martinez, Naveen Reddy, Vivek Sharma We examine spinnability and centrifugally-spun fiber properties for polyvinylpyrrolidone (PVP) by first focusing on the influence of molecular weight and dispersity, and the choice of solvent. A small fraction of high molecular weight (UHMW) PVP is incorporated to illustrate extensibility-enriched spinnability and highlight how nearly similar shear, but quantitatively stronger and different extensional rheology response changes the spinnability outcomes. To elucidate the influence of solvent properties, we vary ethanol content in spinning dope comprising aqueous PVP solutions. We rely on a bespoke centrifugal force spinning (CFS) set-up that allows spinning from two symmetrically placed nozzles onto a collector using matched processing parameters, but variable polymer-solvent concentrations. |
Friday, March 10, 2023 9:00AM - 9:12AM |
Y04.00006: Centrifugal force spinnning and volatile-entangled vs extensibiity-enriched spinnability of polymer solutions Cheryl L Slykas, Jorgo Merchiers, Carina Martinez, Louie Edano, Vihar Trada, Naveen Reddy, Vivek Sharma Designing application-ready fibers involves multifaceted challenges related to correlating the formulation properties and processing parameters to the fiber engineering trifecta of spinnability, morphology, and properties. Here, we characterize the influence of macromolecular and solvent properties on the trifecta for poly(ethylene oxide) or PEO fibers produced using a bespoke centrifugal force spinning (CFS) set-up and matched processing parameters. We illustrate the influence of changing solvent on spinnability, morphology, and properties (thermal and mechanical) by varying acetonitrile (AcN) fraction in the spinning dope formulated with PEO dissolved in AcN:H2O mixtures. We contrast the numerical values of measured diameter, tensile strength, elongation-at-break, and crystallinity of centrifugally spun PEO fibers with the published datasets for electrospun fibers using the Berry number (or the overlap parameter) as the ordinate. We compile, analyze, and replot ES and CFS spinning datasets obtained for various solvents, PEO (Mw and c), and processing parameters. Even though distinct forces determine the jet trajectory and fiber formation for ES and CFS, we find centrifugally spun PEO fibers emulate electrospun fiber properties, morphology, and spinnability. We discuss the mechanism underlying volatile-entangled (VE) spinnability, displayed here by PEO solutions in certain AcN:H2O mixtures, in contrast to extensibility-enriched (EE) spinnability of multicomponent formulations, enabled by the addition of an ultrahigh Mw polymer fraction. |
Friday, March 10, 2023 9:12AM - 9:24AM |
Y04.00007: On Polyethylene Oxide – Polyvinylidene Fluoride Blends and their Nanofibers Alexandro Trevino, Karen Martirosyan, Carlos Delgado, Dorina M Chipara, Manuel Peredo, Karen Lozano, Victoria Padilla, Mircea Chipara Blends of polyethylene oxide (PEO) – Polyvinylidene Fluoride (PVDF) were obtained by using three different procedures: PEO-PVDF(I) blends are obtained by dispersing PEO within deionized water, followed by the addition of the micron-sized PVDF powder and homogenization by sonication. PEO-PVDF(II) blends were obtained by dispersing separately PEO in water and PVDF in acetone and subsequent mixture of the two solutions. PEO-PVDF (III) bends were obtained by dispersing both PEO and PVDF in acetone and then mixing the two solutions. Films of PEO-PVDF were obtained by evaporating the solvent in a vacuum oven at 60 °C. Solutions of PEO-PVDF, containing various amounts of polymer were used to obtain mats of PEO-PVDF(I), (II), and (III) blends via force spinning. The glass transition of PEO is about -50 °C and of PVDF is about – 35 °C. Hence, weak interactions between these macromolecular chains may convert PEO-PDMS into a compatible blend, with a single glass transition temperature. DSC investigations confirmed the interactions between PEO and PVDF chains. Additionally, DSC provided information about the melting and crystallization process, where the melting of PEO is about 65 °C and the melting of PVDF is about 175 oC. |
Friday, March 10, 2023 9:24AM - 9:36AM |
Y04.00008: Soft Matter in 3D Printing: from Polymer Confinement to Nanoparticle Alignment Kenan Song Conventional confinement phenomena include the quantum-confined effect and the polymer chain topologies in thin films. Inspired by these effects, this study will include a few phenomena in the advanced manufacturing of polymer materials that serve as templates to direct the organization and assembly of nanoparticles. The first example is polymer fiber spinning. When nanolayers are created, the nanoparticles will be forced assembled. In this case, the 2D nanoparticles confined with the neighboring polymer layers will be directed to dissipate heat that can be used for intelligent textiles. The second example involves the coating on varying polymer surfaces when the nanoparticles are driven by secondary forces, leading to the ordered stacking of 2D nanoparticles. Subsequently, the demonstration in sensing also shows the potential of using polymer-particle composites for wearable technologies. Last, a new 3D printing with multiplying capabilities has been developed for depositing multiple materials. Nanoparticles under a shear field during extrusion can influence polymer physics, including crystallography and composite mechanics. The focus on the manufacturing-structure-property relationship, especially the nanoparticle assembly with different mechanisms, will be the focus of this research, with demonstration in structural composites, energy storage, and human health. |
Friday, March 10, 2023 9:36AM - 9:48AM |
Y04.00009: Additive Packaging Solutions: RF transparent coatings for heterogeneous IC integration Lucas Unger, Christopher J Molinari, Yuri Piro, Bradley Pothier, sam fedorka, Gary Walsh, Corey Shemelya With the increased demands for hybrid/heterogeneous integrated circuits, there exists a similar need for hybrid and "on-demand" packaging. In order to expand the capabilities of additive manufacturing techniques, we present a transparent Fluoroplastic (THV 221 GZ) based material system which can act as a printable, low RF loss, adhesion promoter and encapsulant. We describe methods to overcome coarse surfaces, flexible substrates, and precise area coverage of thin coatings. Our materials and methods can be used to functionalize a variety of substrates including UHMWPE composite, RF laminate (I-Tera MT40), and Kapton. Additionally, we present multiple formulations for a variety of deposition methods including spraying, extruding, and spreading. As a case-study we demonstrate the integration of pre-packaged ICs, printable material systems, and our THV based coating for increased stability and resilience of RF circuits and sensors fabricated with additive manufacturing (AM) techniques. As the demand for non-traditional packaging and integration increases, this work can offer novel ideas for how AM RF circuits and ICs can be integrated into functional/hybrid devices. |
Friday, March 10, 2023 9:48AM - 10:00AM |
Y04.00010: 1-Second Rapid Shear-Rolling Process for Unidirectionally Aligned and Perpendicularly Oriented Block Copolymer Nano-patterns for a Roll-to-Roll Scale Junghyun Cho, Jeong Gon Son Directed self-assembly of block copolymer (BCP) has been noticed in next-generation lithography as an alternative patterning method. The shear alignment attracts much attention as it can realize macroscopic unidirectional alignment of BCP microdomains. However, static shearing proceeds at a relatively low temperature due to the threat of macroscopic peeling, so the orientation is relatively poor. In the case of soft-shear or laser-shear using a temperature gradient, it is difficult to control the expansion direction of the PDMS located on the top. Moreover, only a unidirectional structure of parallel-oriented cylinders could be realized due to preferential wetting at the upper PDMS interface. Recently, our group realized a unidirectional alignment in a 4-inch scale by developing a shear-rolling process that can sequentially and massively apply shear stress to the BCP films, but it was still a low-temperature process, so repeated rolling was required for high-quality orientation. |
Friday, March 10, 2023 10:00AM - 10:12AM |
Y04.00011: The morphology and phase behavior of diblock polymer double-gyroid thin films Benjamin R Magruder, Kevin D Dorfman The double-gyroid mesophase (DG) has been experimentally observed in diblock polymer thin films, primarily with the (211) plane oriented parallel with the substrate. However, the thermodynamics of these thin films are poorly understood, largely due to a lack of computational research seeking to understand their phase behavior and morphology. Using self-consistent field theory, we modelled DG thin films and studied the resulting 3D composition profiles to identify the phenomena that drive the preference for certain orientations of DG in a thin film, and to predict the conditions at which DG could be the globally stable mesophase. Results show that, in the absence of preferential wetting by either block at the upper or lower interface of the film, the favorability of any given orientation of DG depends on the extent to which the polymers that are in contact with the substrate are able to lie flat with minimal excess chain stretching (which occurs when the A/B interface is normal to the substrate at contact). We predict the stable DG orientation as a function of film thickness, block fraction, and preferential wetting in the DG-forming region of phase space, and identify the factors driving their stability by comparing the relative chain stretching energies of each orientation. |
Friday, March 10, 2023 10:12AM - 10:24AM |
Y04.00012: Influence of Molecular Packing and Confinement on the Glassy State Properties of Polymer Brushes Sneha Srinivasan, Quanyin Xu, Biao Zuo, Rodney Priestley Polymer brushes consist of chains chemically attached to a substrate by one end. The distinctive morphology provides a means to independently control film thickness and molecular packing in a manner not feasible for spin-coated films. As a result, polymer brushes offer a unique opportunity for comparison with spin-coated films and irreversibly adsorbed layers. Indeed, initial investigations suggest that molecular packing has a strong impact on thin film properties, in particular the glass transition temperature. However, there has been less attention focused on the combined influence of molecular packing and confinement on physical aging of thin films. Here, we apply ellipsometry and fluorimetry to investigate the physical aging response of polymer brushes. Specifically, we will consider the impact of confinement on physical aging of polymer brushes by varying film thickness while keeping the grafting density constant. Additionally, we will consider the effects of molecular packing on physical aging by varying grafting density while keeping film thickness constant. Ultimately, this set of investigations will help to elucidate new ways to control thin film material properties. |
Friday, March 10, 2023 10:24AM - 10:36AM |
Y04.00013: Influence of Elasticity on Fingering Instabilities Fahed Albreiki, Vivek Sharma Constant viscosity elastic fluids known as Boger fluids are the ideal choice to investigate the role and influence of elasticity on interfacial flows and instabilities. In this contribution, we charecterize the pinching dynamics and extensional rheology response of model Boger fluids using dripping-onto-substrate (DoS) rheometry protocols, resulting in measurable viscoelastic effects even though elastic properties such as modulus and first normal difference are either below the resolution limit of torsional rheometers or a source of elastic instabilities. We utilize this charecterization to show how elasticity impacts fingering instabilities by visualizing flows in a Hele-Shaw cell and discuss the connections with other free surface flows and instabilities where viscoelasticity can alter pattern formation and evolution. |
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