Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session X10: Physics of Polymers and Polymer Thin Films |
Hide Abstracts |
Sponsoring Units: DPOLY Chair: Sourav Chatterjee, Tulane University Room: 269 |
Friday, March 17, 2017 8:00AM - 8:12AM |
X10.00001: Production of highly mono disperse polymers by evaporative purification Shipei Zhu, Yu Chai, Junjie Yin, Denzil Barkley, James Forrest The polymerization index $N$ is perhaps the most important single parameter describing a polymer. For example this parameter is crucial, especially for small N, in determining the phase separation behavior and glass transition temperature of polymers. Even the best controlled synthetic polymers with excellent polydispersity index (PDI $\sim$ 1.01) are still far from being purely monodisperse. We demonstrate the use of thermal evaporation to separate different monodisperse components in a polymer sample. For example, we are able to use a sample of anionically polymerized polystyrene (with PDI of 1.1) to produce macroscopic amounts of monodisperse polymers (or N-mers) of N values ranging from 2 to 10. We estimate the PDI of these monodisperse samples to be less than 1.005. The measured $T_g$ values of these components range from 220K to 300 K. We will discuss physical characterization of the N-mers, and the application of this technique to other polymers. [Preview Abstract] |
Friday, March 17, 2017 8:12AM - 8:24AM |
X10.00002: Tackiness of Polymer Melts. Aiping Zhou, Xiaorong Wang Understanding tackiness is important for many industrial applications. This work studies the most basic and important tacky behavior of entangled linear polyisoprenes of various molecular weights to a stainless steel surface. The maximum tacky force ($F_{max})$ is found to be influenced by many factors, e.g., contact time, separation speed, polymer molecular weight, temperature and etc. However, there is one thing in common: when the probe separation speed ($v)$ is greater than a critical speed ($v_{c})$, the force $F_{max}$ can be described by a power function $F_{max}\propto t_{max}^{\mathrm{-1/2}}$, where $t_{max}$ is the time corresponding to the maximum force at constant separation. When the separation speed is less than $v_{c}$, the force $F_{max}$ is nearly independent of $t_{max}$ and separation speed, apparently existing a plateau regime. Further decreasing the separation speed eventually moves a material into the terminal flow regime, in this case $F_{max}$ scans like $F_{max}\propto t_{max}^{\mathrm{-1}}$. The tackiness of entangled linear polymer melts is basically associated with the viscoelastic dissipation and characteristics of the entangled polymer chains at the contact interface.. [Preview Abstract] |
Friday, March 17, 2017 8:24AM - 8:36AM |
X10.00003: Capillary Levelling of Cylindrical Holes in Freestanding Polymer Films John Niven, Paul Fowler, Thomas Salez, Howard Stone, Élie Raphaël, Kari Dalnoki-Veress Studying nano-scale flow in thin viscous films is of both practical and theoretical interest, particularly when considering the role of the hydrodynamic boundary conditions. Here, thin bilayer polystyrene films were prepared freestanding in air, with one of the two films having micrometer scale cylindrical holes. Because of the free interfaces, such films flow without interfacial friction at either surface. The viscoelastic relaxation of the holes was studied using atomic force microscopy. The temporal evolution of the holes shows three distinct regimes: an early time regime where the film undergoes an elastic response; an intermediate regime where the hole undergoes viscoelastic symmetrization to equilibrate internal Laplace pressure; and a late time regime where the film undergoes capillary driven flow. [Preview Abstract] |
Friday, March 17, 2017 8:36AM - 8:48AM |
X10.00004: Characterization of Polystyrene Soft Nanoparticles Using Small Angle Neutron Scattering Halie Martin, Tyler White, Tomonori Saito, Mark Dadmun Polymer nanocomposites have become a prominent area of research recently. With a growing variety of nanoparticles available, research probing the influence of particle morphology on the overall nanocomposite properties is also increasing. Nanoparticle dispersion is controlled by both the chemical nature and morphology of the nanoparticle where a crosslinked, fuzzy organic nanoparticle is anticipated to enhance the overall miscibility and create a homogenous dispersion within a like-polymer matrix. A semi-batch microemulsion polymerization forms organic, soft nanoparticles where the precise structure of the nanoparticle is controlled by monomer rate of addition and crosslinking density. We will report small angle neutron scattering results that correlate synthetic conditions to the structural characteristics of soft nanoparticles. This analysis provides characterization of the individual nanoparticle molecular weight, the radius of the crosslinked core, the thickness of the fuzzy interfacial layer, and provides insight into the overall topography of the soft nanoparticle. This research provides a pathway to investigate the effect of nanoscale structural features of the nanoparticle on their individual properties and those of nanocomposites that contain these soft nanoparticles. [Preview Abstract] |
Friday, March 17, 2017 8:48AM - 9:00AM |
X10.00005: Single fluorophore localization and orientation reports structure and deformation at the nanoscale Muzhou Wang, James M. Marr, Marcelo Davanco, Jeffrey W. Gilman, J. Alexander Liddle Super-resolution microscopy offers an exciting method to image nanostructures non-invasively, opening the possibility of direct in situ real-space observation at the nanoscale. Most previous studies have applied these techniques to important scientific problems in the biological community, but little work has explored their use in materials science, where important effects such as dye chemistry and fluorophore orientation introduce new demands. Here we apply photo-activated localization microscopy (PALM) to polymer films nanopatterned using electron-beam lithography. Our fluorophore localization precision and accuracy are less than 10 nm, and we are able to resolve features as small as 20 nm. In addition, we demonstrate that single fluorophore orientation can be determined from the shape of their in-focus images. Combined with localization, orientation offers an additional reporter of nanoscale environment within a material. This capability is demonstrated on polymer films that have been deformed through nanoimprint lithography, and the orientation provides information about local stress and damage experienced during the fabrication process. [Preview Abstract] |
Friday, March 17, 2017 9:00AM - 9:12AM |
X10.00006: Template-guided highly aligned, nano-scale wrinkle structure on a large-area Jongcheon Lim, Pilnam Kim This study presents a novel technique to induce aligned, nano-scale wrinkle on a polysiloxane-based UV curable resin. There have been studies on generating randomized sub-micron wrinkle using oxygen plasma treatment which causes equibiaxial compressive stress on the film surface. Few works have been reported on how to control the surface wrinkle orientation. Currently available approaches for regulating the wrinkle pattern typically require polydimethylsiloxane (PDMS)-based bilayer system under uniaxial stress condition which hampers various technological applications. Here, we demonstrate a method to generate aligned wrinkle with UV curable polymers. Highly regular array of nanoscale wrinkles were formed by elastic buckling of bilayered UV curable resin, resulting from a combination of confinement effect and anchor-guided propagation of structure. The wrinkle tends to align uniformly lateral to the template pattern as the resin filled in the pattern forms more convex meniscus. The wavelength of the wrinkle was controlled by UV exposure time yielding as small as 170nm. From our results, we suggest the confinement provided by the template pattern may have affected the direction of thin film's expansion yielding unidirectional compressive stress. [Preview Abstract] |
Friday, March 17, 2017 9:12AM - 9:24AM |
X10.00007: Capillary bending of a thin polymer film floating on a liquid bath Timothy Twohig, Andrew B. Croll Thin elastic films and shells are very important in schemes for the encapsulation and protection of fluids from their environment. Capillary origami is a particularly poignant example of how useful fluid/film structures can be formed. The interactions of fluids on thin-films which themselves lie on another surface (fluid or low friction solid) need to be studied if the differences from fluid-fluid and fluid-solid film interfaces are to be fully appreciated. In this experiment, we examine the triple line that occurs when a fluid is resting on a thin polymer film which is itself floating on a second fluid. The top fluid has a high-energy air/fluid interface which can be minimized by deforming the film in a manner that reduces the total air/fluid interface. We create a one-dimensional experiment in order to isolate the basic physics that occurs as the tension of the top fluid pulls on the thin film. Notably, the 1D geometry removes all the complexity incurred by thin films in biaxial stress states (such as wrinkling, folding and crumpling) from the problem. [Preview Abstract] |
Friday, March 17, 2017 9:24AM - 9:36AM |
X10.00008: Morphological Study of Langmuir Polymer Films by means of Atomic Force Microscopy and MD Simulations Renate Reiter, Volker Knecht, Sivasurender Chandran, Günter Reiter In general it is difficult to reproduce well defined morphologies of Langmuir polymer films (LPFs) because they have a high propensity to form non-equilibrium states. We present a systematic study based on different compression protocols designed to allow for relaxations of LPFs under well defined conditions. The homo peptide poly-γ-benzyl-L-glutamate (PBLG) was chosen for this study because it is a well investigated system that represents the relaxational behaviour of rod-like molecules which is expected to show less complexity than coiled polymer molecules. Our results demonstrate that experimentally manipulating the course of relaxations in LPFs has tremendous impact on the ordering of the molecules. Coarse grain molecular dynamics simulations were performed under comparable conditions. The results match the experimental observations reasonably well and allow to zoom into molecular details which are not resolved experimentally. [Preview Abstract] |
Friday, March 17, 2017 9:36AM - 9:48AM |
X10.00009: Single Nanometer Thickness of Polymer Nanocapsules Measured using Small Angle Neutron Scattering Andrew Richter, Sergey Dergunov, Eugene Pinkhassik We have been creating polymer nanocapsules using a directed assembly approach in which hydrophobic monomers, crosslinkers, and pore-forming templates are localized in the hydrophobic interior of the surfactant bilayer of vesicles that are 50 -- 200 nm in diameter. Polymerization and rinsing results in hollow polymer spheres with well-defined pores that can be used as a platform for drug delivery, sensing, and catalysis applications. Many of these applications rely on the polymer shell to be as thin as possible so as to maximize the interior cargo space and to allow for fast mass transport through the shells. Directly measuring that thickness has proven to be difficult due to the small amount of material comprising the wall, adequate dispersal of the nanocapsules in solution, and the lack of contrast between the wall and the solvent, among other issues. We have recently completed a series of small-angle neutron scattering experiments that push the edge of the capability of the technique that show that the polymer shell is only 1 nm thick, making these shells some of the thinnest membranes ever fabricated. We will present that analysis and discuss some of the complicating factors in performing this measurement. [Preview Abstract] |
Friday, March 17, 2017 9:48AM - 10:00AM |
X10.00010: Amorphous Cellulose Thin Films Howard Wang, Rui Lu, Xin Zhang, Robert Briber, Li Fu, Hongfei Wang, Guangcui Yuan Amorphous cellulose thin films with sub-nanometer roughness and 8 - 100 nm thicknesses have been fabricated by spin casting from molecular solutions of cellulose in mixtures of ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc) and organic solvent dimethyl sulfoxide (DMSO). Combining advanced x-ray, optical and scanning probe measurements, cellulose films are found be pure cellulose, free of residual EMIMAc and DMSO, as well as truly amorphous, free of crystallites. The mass density of films with thickness greater than 30 nm is ca. 1.497 g.cm$^{-3}$, approaching that of the bulk amorphous cellulose. The fraction of voids is ca. 1.7 \% in ultrathin 8 nm film, and decreases to 0.25 \% in thicker films. The equilibrium state of the amorphous cellulose films is achieved through successive diffusion of ionic liquid molecules out of cellulose films with simultaneous formation of hydrogen bonding among cellulose chains. [Preview Abstract] |
Friday, March 17, 2017 10:00AM - 10:12AM |
X10.00011: Noncontact viscoelastic measurement of polymer thin films in a liquid medium using a long-needle AFM Dongshi Guan, Chloe Barraud, Elisabeth Charlaix, Penger Tong We report noncontact measurement of the viscoelastic property of polymer thin films in a liquid medium using frequency-modulation atomic force microscopy (FM-AFM) with a newly developed long-needle probe. The probe contains a long vertical glass fiber with one end adhered to a cantilever beam and the other end with a sharp tip placed near the liquid-film interface. The nanoscale flow generated by the resonant oscillation of the needle tip provides a precise hydrodynamic force acting on the soft surface of the thin film. By accurately measuring the mechanical response of the thin film, we obtain the elastic and loss moduli of the thin film using the linear response theory of elasto-hydrodynamics. The experiment verifies the theory and demonstrates its applications. The technique can be used to accurately measure the viscoelastic property of soft surfaces, such as those made of polymers, nano-bubbles, live cells and tissues. This work was supported by the Research Grants Council of Hong Kong SAR. [Preview Abstract] |
Friday, March 17, 2017 10:12AM - 10:24AM |
X10.00012: Dewetting Kinetics in Polymer Grafted Nanoparticle Thin Films: Impact of Architecture and Viscosity on Thermal Stability Justin Che, Ali Jawaid, Christopher Grabowski, Yoon-Jae Yi, Richard Vaia Rapid formation of ordered monolayers of polymer grafted nanoparticles (PGN) directly onto solid surfaces has spurred interest in using these materials for additive manufacturing of optical devices and energy storage. Herein, we discuss dewetting of polystyrene grafted Au nanoparticles (PS@Au) with an increased thermal (10-25$^{\mathrm{o}}$C) and energetic (5-15 mN/m) stability relative to linear polymer films of comparable thickness. Analogous to star macromolecules, the enhanced stability is related to the conformations of chains in the grafted canopy. Mechanistically, dewetting of PS@Au is similar to linear PS, however, the thickness transition from spinodal to heterogeneous nucleation is at least 5-6x larger. Time resolved optical microscopy during dewetting at 160$^{\mathrm{o}}$C revealed that the zero shear viscosity for linear PS scaled as $\eta_{\mathrm{0\thinspace }}\sim $ M$_{\mathrm{n}}^{\mathrm{3.3}}$, consistent with reptation of entangled polymers. In contrast, PS@Au showed $\eta_{\mathrm{0\thinspace }}\sim $ M$_{\mathrm{n}}^{\mathrm{2.2}}$ where Mn reflects the molecular weight of the grafted chains. Overall, PS@Au exhibited significantly slower dewetting rates, consistent with a $\sim $ 100x increase in viscosity relative to the linear chain analogues. Quantification of the relationship between PGN architecture (e.g. nanoparticle size, graft density, polymer molecular weight) and dewetting processes is crucial to optimize the order of these assemblies via post-processing, as well as design the PGN canopy to maximize stability for devices. [Preview Abstract] |
Friday, March 17, 2017 10:24AM - 10:36AM |
X10.00013: Fabrication of Micropatterned, Free-Standing, Flexible Thin Films of SU8 and SQ Luke D'Imperio, Andrew F. McCrossan, Jeffrey R. Naughton, Yitzi M. Calm, Juan M. Merlo, Michael J. Burns, Michael J. Naughton Motivations for improving techniques and devices in thin film sciences are numerous in areas such as thin film electronics, medical devices, etc. We describe the fabrication and characteristics of free-standing, flexible, optically transparent, micropatterned thin films made from negative photoresists SU8 and SQ.~We motivate the importance of film thickness for applications in localized optical throughput from light sources. We demonstrate the robust and flexible qualities of samples in interest of possible uses in wearable electronics. We outline our next steps in the development of a platform for highly localized optical stimulation and electrical recording for e.g. bioelectronics and optogenetics. [Preview Abstract] |
Friday, March 17, 2017 10:36AM - 10:48AM |
X10.00014: Anomalous Behaviors of Block Copolymers at the Interface of an Immiscible Polymer Blend Ji Ho Ryu, Won Bo Lee We investigate the effects of structure and stiffness of block copolymers on the interface of an immiscible polymer blend using coarse-grained molecular dynamics (CGMD) simulation. The diblock and grafted copolymers, which are described by Kremer and Grest bead spring model, are used to compare the compatibilization efficiency, that is, reduction of the interfacial tension. It is found that, overall, the grafted copolymers are located more compactly at the interface and show better compatibilization efficiency than diblock copolymers. In addition, it is noted that an increase in the stiffness of one block of diblock copolymer causes inhomogeneous interfacial coverage due to bundle formation among the stiff blocks and orientational constraint on bundled structures near the interface, which makes copolymers poor compatibilizers. The dependence of anomalous orientational constraint on the chain length of homopolymers is also investigated. [Preview Abstract] |
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