Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session B26: Wetting, Adhesion, and Tribology of Soft Interfaces IIRecordings Available
|
Hide Abstracts |
Sponsoring Units: DSOFT DPOLY GSNP Chair: Krishnaroop Chaudhuri, University of Kentucky Room: McCormick Place W-187B |
Monday, March 14, 2022 11:30AM - 11:42AM |
B26.00001: Role of Backbone versus Catechol Hydrophobicity in removing Interfacial Water Abdol Hadi Mokarizadeh, Nityanshu Kumar, Abraham Joy, Ali Dhinojwala, Mesfin Tsige Adhering to surfaces underwater has been a challenge since decades. The marine life such as sand worm castle, barnacles and mussels has taught researchers strategies to remove interfacial water and get hold of surfaces. Mussels use their foot-proteins, i.e., rich in catechol units to bind to different surface chemistries underwater. This observation stimulated the synthesis of catechol-based adhesives which are shown to adhere to all kind of surfaces underwater in literature. However, recently with controlled experiments, researchers have argued and pointed towards the role of backbone hydrophobicity in removing the interfacial water. Even though, the community has a consensus on the role of catechol hydroxyl groups in underwater adhesion, the driver for removal of water from different surfaces is still unknown/debated. In this work, we perform molecular dynamics simulations of catechol based underwater adhesives on self-assembled monolayers and metal oxide surfaces. We will discuss the water structure and the potential required to remove water from vicinities of different groups which expectantly will demarcate the backbone versus catechol hydrophobicity. |
Monday, March 14, 2022 11:42AM - 11:54AM |
B26.00002: Soft, coarse-grained modelling of self-assembling polymer ink Ludwig Schneider, Juan De Pablo We model the experimental technique of printing nano-meter-sized polymer droplets onto a prefabricated substrate to direct and validate the efforts of our experimental collaborators. We model the interaction parameter between the polymer blocks and the surface interaction. As a result, we are able to control the microphase-separated morphology inside the droplet. In contrast to a bulk system, we have here the interaction between with the surface and the soft, spatial constraints of the droplet. |
Monday, March 14, 2022 11:54AM - 12:06PM |
B26.00003: Multi-functional fin texture controlled by dynamic elastocapillary effect Yun Seong Kim, Jonghyun Ha, Jonghyun Hwang, Sze Chai Leung, Sameh H Tawfick Soft fins can deform by the elastocapillary effect which originates from the surface tension of liquid menisci. We design reconfigurable surface textures consisting of fins with polymorphic self-assembly mode shapes controlled by dynamic fluid drainage. We discovered that the self-assembly mode shapes are selected by fluid dynamics, which is different from conventional systems that only have single mode shape for one geometry. In the presentation, we will first describe the design and fabrication of slender single and multiple fin geometries using molds produced by additive manufacturing. Next, the fin bending mechanism is explained by theoretical scaling laws that capture the phenomena on various fin geometries, including their length and the spacing between the fins and the walls. Lastly, some application of reconfigurable texture, such as letter display and message encoding in optical and IR regime, will be shown. |
Monday, March 14, 2022 12:06PM - 12:18PM |
B26.00004: Science Al dente: Elastocapillarity and Swelling of Cooked Pasta Jonghyun Hwang, Jonghyun Ha, Ryan Siu, Yun Seong Kim, Sameh H Tawfick Food cooking involves diverse chemical and physical reactions, along with an opportunity to connect us to science on a daily basis. Examples include the boiling of eggs, caramelization of the sugar, softening and hardening of bread as function moisture, and cooking and adhesion of noodle strands. Here, we theoretically and experimentally investigate the elastic deformation of pasta noodles as a function of cooking duration and temperature. We submerge two pasta noodles fixed at the top into a hot water tank, then pull them out. The two noodles elastically deform and adhere together due to capillary action. We observe that the stick length of pasta noodles – the distance between the fixed end of pasta and the liquid meniscus between the noodles – decreases as cooking time increases. The duration of cooking affects the swelling of the pasta and its modulus. Liquid migration into the material by diffusion causes radial growth due to hygroscopic swelling and several orders of magnitude drop in Young’s modulus (softening). This, in turn, softens the outer layers of this slender structure, making it more susceptible to deformation by capillary forces. Considering the diffusion dynamics within the pasta, we developed the theoretical model that treats the pasta as a hard core-soft shell structure to predict the stick length at various cooking times, which is corroborated with experimental results. We anticipate that the current work can provide an optimal cooking time finely tuned based on predictive models for various kinds of pasta shapes. |
Monday, March 14, 2022 12:18PM - 12:30PM |
B26.00005: Critical Packing Density of Water-Mediated Nonstick Self-Assembled Monolayer Coatings Hsieh Chen Nanoparticle-mineral surface interactions are relevant in many biological and geological applications. We have previously studied nanoparticle coatings based on closely packed bicomponent polyol-fluoroalkane self-assembled monolayers (SAMs) that can have tunable stickiness on calcite surfaces by changing the compositions of the fluoroalkanes in the SAMs, where the coatings show nonstick properties if the fluoroalkanes can effectively perturb the hydration layers on the calcite surfaces. However, when applying coatings on nanoparticles, it can be challenging to predict the maximum achievable coating density. Here, we study how would the water-mediated SAM-calcite interactions change with different SAM coating densities. Molecular dynamics simulations show that compositionally repulsive closely packed polyol-fluoroalkane SAMs become adhesive to calcite surfaces with decreasing coating densities. Our modeling shows that this results from the collapsing of the fluoroalkanes into the voids of the SAMs, where the fluoroalkanes can no longer perturb the hydration layers on calcite surfaces. Interestingly, we find that the nonstick-stick transition occurs when the volume fractions of the voids on the SAMs are greater than the volume fractions of the hydrophilic coating molecules. |
Monday, March 14, 2022 12:30PM - 12:42PM |
B26.00006: Attractive forces slow contact formation between the deformable bodies underwater Mengyue Sun, Nityanshu Kumar, Ali Dhinojwala, Hunter King Adhesion and friction between surfaces that touch are known to depend sensitively on gaps of near contact down to the nanoscale. While chemical affinity, compliance and roughness of the surfaces determine the thermodynamic state of contact, the actual state also depends on dynamics of its formation, which can depend on interplay between both surface properties and those of the mediating fluid. Presence of water changes the adhesive interaction between surfaces, while its resistance to evacuate the contact region frustrates its formation by leaving behind nanoscopic puddles. By high-resolution, in-situ, Frustrated Total Internal Reflection (FTIR) imaging, we track the evolution of contact between soft-elastic hemispheres of varying stiffness and smooth–hard surfaces of varying wettability. We find the exponential rate of water evacuation from hydrophobic–hydrophobic (adhesive) surfaces is 3 orders of magnitude smaller than that from hydrophobic–hydrophilic (non-adhesive) contact. This counterintuitive result comes from adhesive surfaces to more tightly sealing puddles of trapped water. Similar observation for a human thumb touching alternatively hydrophobic/hydrophilic glass surfaces, demonstrates generality of the mechanism and points to practical consequences. |
Monday, March 14, 2022 12:42PM - 12:54PM |
B26.00007: A Modular 90° Test Configuration for Measuring Tape Adhesion on Immovable Substrates Jared A Gohl, Trevor C Thiele-Sardina, Mitchell L Rencheck, Kendra A Erk, Chelsea S Davis Temporary pavement markings (TPMs) are a critical safety tool for both road workers and drivers during construction on active roadways. TPMs are viscoelastic pressure sensitive adhesive (PSA) tapes with a reflective layer embedded in them. To better characterize the adhesive performance of these tapes, a new testing methodology has been developed to perform peel testing of PSA tapes from immovable substrates, which are commonly assessed using 90º peel tests.Work of detachment (W) is calculated as: W=P/b(1-cosθ) where P is the peeling force, b is the tape width, and θ is the peeling angle. Typical 90º peel test fixtures translate the substrate as the force is applied, precluding roadway testing. Our novel methodology allows for peel testing of PSA tapes from immobile substrates through a custom peeling fixture. We have performed tape rate (0.05-10.0 mm/s) and width (6.35-25.40 mm) qualification experiments with transparent office tape to validate the methodology. The methodology is sensitive enough to detect the linear response of W with respect to width and the viscoelastic response of the tape. |
Monday, March 14, 2022 12:54PM - 1:06PM |
B26.00008: Elastocapillary kirigami Marcelo A. Dias, Souhayl Sadik Kirigami--the ancient Japanese art of paper cutting--inspired a myriad of applications in different fields and across multiple scales. It has been found to be of special relevance to applications in reconfigurable structures (e.g., large deployable structures) and microstructures (e.g., stretchable graphene sheets). Indeed, careful tailoring of cut patterns in thin elastic sheets results in structures with interesting non-linear macroscopic responses emerging from local out-of-plane buckling [1,2]. The rise interest in kirigami, combined with the emergence of recent technological developments in manufacturing techniques of fluid-like soft materials, has ushered in a new generation of industrial applications and motivated this work on elastocapillary kirigami. Using the mean-field formulation, we study the interaction of a thin elastic sheet of kirigami with a fluid substrate [3]. Within this framework, we classify the critical behaviour of linear-cut kirigami over a fluid substrate with respect to symmetry considerations at the level of the unit cell. The analysis reveals that the anti-symmetric post-buckling configuration displays a discontinuous (first order) phase transition with respect to imposed normalised displacement; which suggests phase localisation as the individual cell gets trapped in a meta-stable state and the subsequent phase propagation through kirigami structures. In contrast to this, the symmetric post-buckling configuration deforms continuously via a second order phase transition; which suggests a continuous phase transition. The theoretical analysis is supported by a body of experiential work confirming the existence of buckling localisation and its subsequent propagation in linear-cut kirigami. |
Monday, March 14, 2022 1:06PM - 1:18PM |
B26.00009: Contact of soft solids on rigid substrates mediated by air John M Kolinski Before a soft solid can impact upon a rigid substrate, it must drain the air beneath it. If the impact is sufficiently rapid, the air will fail to drain, and instead compresses. Indeed, the air can compress sufficiently to significantly deform the soft impactor. Here we explore a critical transition in the dynamics between two regimes: first, where elastic and lubrication stresses balance, and second, where inertial and lubrication stresses balance. Using direct imaging of the interface with sub-micron resolution in our experiments, and varying the impactor's stiffness and geometry, we show how the progressing deformation front of the soft impactor can exceed the Rayleigh velocity of the impactor to fundamentally alter the contact dynamics. The transition between elastic and inertial stress dominance can be extremely sharp, highlighting an unexpected and rich dynamics during dynamic impact of compliant solids, with key implications for systems as diverse as biotribological interfaces, dense suspensions and the mundane rebound of a bouncy ball. |
Monday, March 14, 2022 1:18PM - 1:30PM |
B26.00010: Delamination of open cylindrical shells from soft and adhesive Winkler's foundation Oz Oshri We investigate the equilibrium configuration of an open cylindrical shell with natural curvature κ and bending modulus B, that is adhered to a soft and adhesive foundation with stiffness K. We derive an analytical model that predicts the critical conditions for delamination. While in the case of a rigid foundation, K→∞, our model recovers the known, two states, solution, at which the shell either remains completely attached to the substrate or completely detaches from it, on a soft foundation our model predicts the emergence of a new branch of solutions. This branch corresponds to partially adhered shells, where the contact zone between the shell and the substrate is finite and scales as (B/K)1/4. In addition, we find that the criterion for delamination depends on the total length of the shell along the curved direction, L. While relatively short shells, L∽(B/K)1/4, transform continuously between adhered and delaminated solutions, long shells, L»(B/K)1/4, transform discontinuously. |
Monday, March 14, 2022 1:30PM - 1:42PM |
B26.00011: Multiscale Soft Surface Instabilities for Adhesion Enhancement VAISAKH V M, Qin Xu, Ho Yi Lydia Mak, Nishan Gurung Soft systems due to their innate aspects (low elastic moduli and exorbitant response to external stimuli) are susceptible to buckling induced surface instabilities. Surface instabilities in soft materials are fascinating to study upon due to their potential to be developed into functional materials, to model real-life biological tissues, etc. |
Monday, March 14, 2022 1:42PM - 1:54PM |
B26.00012: SURFACE GRAFTED POLY(IONIC LIQUID) THAT LUBRICATES IN BOTH NON-POLAR AND POLAR SOLVENTS Zhenyu J Zhang, David Burgess, Nicole Rosik, Peter Fryer, Na Li, Ian McRobbie, Haining Zhang Following a series of studies concerning the tribological characteristics of polyzwitterionic brushes [1-4], we show that 1-n-butyl-3-vinyl imidazolium bromide based poly(ionic liquids) (PIL) samples is able to reduce the interfacial friction by up to 66% and 42% in both non-polar (dodecane) and polar (water) solvents respectively [5]. This is unusual for surface grafted polymer that delivers lubrication when the polymer chains are well solvated. Both chemical moieties and polymerisation time could influence the lubrication introduced by the PIL brushes. AFM based force spectroscopy reveals that the polymer brush adopts distinctively different interfacial conformations: swollen in water but collapsed in dodecane. However, minimal surface adhesion was observed with both polymer conformations, which can be attributed to steric repulsion as the result of a swollen conformation in water, or surface solvation when the hydrophobic fraction of the polymer was exposed to the dodecane. The work brings additional insight on polymer lubrication mechanism, which expands the possible design of polymer architecture for interfacial lubrication and modification. |
Monday, March 14, 2022 1:54PM - 2:06PM |
B26.00013: Soft coring: how to get a clarinet out of a flute? Frederic Lechenault, Matteo Ciccotti As an everyday gesture, slicing can be frustrating in different ways. Cutting through a mozzarella ball with a dull blade will most certainly result in a poorly shaped slice, as the celebrated cheese will deform before it's cut, resulting in potentially disgraceful bites. Cutting occurs in a configuration so deformed as to give rise to a whole different shape once the process of cutting is achieved. We study the rich morphogenetics arising from such process through the example of coring: when a thin cylindrical metal tube is pushed into a soft elastomer, the extracted core is hour-glass shaped, reaching diameters far smaller than that of the coring tool. Assembling contributions from fracture mechanics, large deformation theory and friction, we build a simple yet quantitative understanding of the observed shapes and dynamometrics. Our study opens perspectives into complex programmable surface shaping, in a mundane, accessible setting fitted for an array of design applications. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700