Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session B52: Polymer Crystallization from Classical to Functional Systems IIFocus
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Sponsoring Units: DPOLY Chair: Christopher Li, Drexel Univ Room: LACC 512 |
Monday, March 5, 2018 11:15AM - 11:51AM |
B52.00001: Anisotropy of charge transport and thermoelectric properties in oriented conducting polymer films prepared by high temperature rubbing Invited Speaker: Martin Brinkmann
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Monday, March 5, 2018 11:51AM - 12:03PM |
B52.00002: Achieving Relaxor Ferroelectric Behavior in Nylon-based Polymers Lei Zhu, Zhongbo Zhang, Morton Litt High dielectric constant polymers, exhibiting relaxor ferroelectric behaviors (i.e., slim single and double hysteresis loops), are attractive for high energy density and low loss dielectric applications. Utilizing the principle of nanosized ferroelectric domains (nanodomains), this work has designed and developed novel relaxor ferroelectric polyamides (PAs or nylons) as an alternative to the high-cost and difficult-to-synthesize poly(vinylidene fluoride) (PVDF) based relaxor ferroelectric polymers. For nylon-based polymers, the mesomorphic crystalline structure is important for the electric field-induced ferroelectricity. First, slim double hysteresis loop behavior can be achieved for even-numbered nylons at high temperatures. Second, the slim single hysteresis loop behavior can be achieved in PA terpolymers at high temperatures. Pathways to achieve relaxor ferroelectric behaviors for nylon-based polymers are discussed and compared with those for PVDF-based polymers. The knowledge obtained from this study can inspire potential applications for nylon polymers in advanced electrical and power applications. |
Monday, March 5, 2018 12:03PM - 12:15PM |
B52.00003: Manipulating Crystallization Sequence in PEO-b-PCL Copolymers Ryan Van Horn, Natasha Brigham, Christopher Nardi, Kristi Allen, Allison Carandang Crystalline-crystalline diblock copolymers have a hierarchical crytsallization process based on the relationship among the order-disorder temperature, melting temperature for the first block, and melting temperature for the second block, TODT, Tm1, and Tm2, respectively. When Tm1 ≈ Tm2, the crystallization mechanism becomes more complex due to coincident crystallization, where the weight fractions are nearly equal, w1 ≈ w2), or sequential crystallization, where w1 > w2 and diluent or confinement effects influence nucleation of the second block. In our research, the goal is to understand these mechanisms better and to manipulate them in order to change the microscopic structure, and therefore, the macroscopic properties. A model diblock copolymer for this work is PEO-b-PCL since TmPCL ≈ TmPEO. One method to manipulate the crystallization mechanism is to use different casting solvents when making PEO-b-PCL films. The work presented here shows that the order of nucleation during drying in PEO-b-PCL films, where wPCL ≈ wPEO, can be switched based on selective solvent interactions. |
Monday, March 5, 2018 12:15PM - 12:27PM |
B52.00004: Polymer crystallization at large supercooling, studied by modified Fast Scanning Calorimetry Evgeny Zhuravlev, Dongshan Zhou, Jing Jiang, Christoph Schick Polymer crystallization in the vicinity of glass transition still remains the point of large controversy [1]. Time and size of the involved rearrangements places certain challenge for instrumentation and experimental design. Fast Scanning Calorimetry (FSC) introduced by [2] brought vast possibilities for polymer vitrification and crystallization study. It can follow up crystallization/vitrification at cooling rates up to 1,000,000 K/s under condition of liquid nitrogen cooled gas environment. Separation of heat treatment and analysis temperature scans gives even more opportunities e.g. for crystal nucleation rate measurement [3]. Combination of structural technique is vitally important. Because most of the technique are unable to reach the rate of cooling offered by FSC, multi-stage experiment design becomes useful. Precisely ordered material shall be frozen, or allowed to develop at different temperature for determination of needed parameters under AFM or optical microscopy. Combination of FSC, AFM and optical microscopy was used to follow homogeneous nucleation of PBT. |
Monday, March 5, 2018 12:27PM - 12:39PM |
B52.00005: Impact of Tungsten Disulfide Nanotubes on the crystallization of poly(l-lactide) for thinner and stronger bioresorbable vascular scaffolds (BVS) Tiziana Di Luccio, Karthik Ramachandran, Zach Zixuan Shao, Loredana Tammaro, Carmela Borriello, Fausta Loffredo, Fulvia Villani, Francesca Di Benedetto, Sandy Leung, Tony McNally, David Boyd, Julie Kornfield Bioresorbable Vascular Scaffolds (BVSs) are transient implants that can revolutionize the treatment of coronary heart disease by restoring vasomotion in the occluded artery. However, the adoption of pure poly L-lactide (PLLA) BVSs is hindered by their thickness (150µm), which is nearly twice that of metal stents. A thinner scaffold is easier to implant and can treat smaller lesions. A BVS reinforced with biocompatible Tungsten Disulfide (WS2) nanotubes (WSNTs) offers a solution towards a thinner, stronger BVS. To understand the impact of WSNTs on PLLA during processing, we subject PLLA and PLLA-WS2 (0.05wt%, 0.1wt%) to a shear pulse and probe the evolution of birefringence in real time. We discovered that WSNTs favor the formation of “shish-kebabs” in PLLA. Thread-like precursors that grow into shish are characterized by an upturn in birefringence during flow and kebabs are detected by an increase in birefringence after cessation of flow. Intriguingly, PLLA and PLLA-WS2 (0.05%) lack an oriented skin along the flow-direction, but possess a skin normal to the flow-direction. However, PLLA-WS2 (0.1%) exhibits a skin along both directions. We are investigating further upon this unexpected morphology and the role of WSNTs in enabling a thinner, stronger BVS. |
Monday, March 5, 2018 12:39PM - 12:51PM |
B52.00006: Determining Polymer Spherical Crystal Disorder by Thermal and Spectroscopic Techniques Mark Staub, Christopher Li Spherical crystallography is concerned with crystallization in curved space where the dimensions of the crystalline lattice and the inverse curvature are comparable, so that the three-dimensional translational symmetry and the curved space diverge. This results in a necessary disorder within the crystal manifesting as defects and lattice modifications serving to break the symmetry to accommodate the curved space. Non-planar crystal morphologies are seen in polymer crystals and exercising control over their temporal and spatial evolution can produce unique and useful nanostructures. Our group has recently developed a method to grow poly (L-lactic acid) single crystal-like polymer capsules termed “crystalsomes” utilizing a miniemulsion system. This serves as a model system to study spherical crystallography. Diffraction techniques were used in conjunction with thermal and spectroscopic techniques to probe the crystalsome structure. We show the curvature effect on polymer chain packing by comparing crystalsomes and the corresponding flat single crystals. |
Monday, March 5, 2018 12:51PM - 1:03PM |
B52.00007: Melting and crystallization temperatures of semi-crystalline polymer thin films studied via spectral reflectance Giovanni Kelly, James Elman, Zhang Jiang, Joseph Strzalka, Julie Albert For semi-crystalline polymers, the melting and crystallization temperatures play critical role in understanding the importance of supercooling on the kinetics of crystallization. Thus, being able to measure changes in the melting and crystallization temperature as a function of thin film confinement is incredibly important. Until recently, these measurements required the use of highly sophisticated and expensive equipment such as nano-DSC, ellipsometry, or grazing-incidence wide angle X-ray scattering (GIWAXS). We have shown that that spectral reflectance, a widely used and inexpensive technique for measuring film thickness, can be used to identify the melting and crystallization transitions in thin films (500 nm down to 20 nm thickness) with single degree resolution. This approach is based on measuring characteristic expansion and contraction profiles during the melting and crystallization transitions, respectively. We have validated this technique against DSC, GIWAXS, and atomic force microscopy. Additionally, we show that in poly(caprolactone) thin films, the melting temperature is not affected by film thickness whereas poly(ethylene glycol) thin films show a strong melting point depression with decreasing film thickness. |
Monday, March 5, 2018 1:03PM - 1:15PM |
B52.00008: Polymer Crystallization on the Ice Surface Kyoungwook Kim, Moon Jeong Park Great attention has been paid to conducting polymers owing to their high electrical conductivity, processability, and environmental benignity. Such advantages suggest potential uses of the conducting polymers in a range of electronic devices. In literature, much of research efforts have been devoted to increase the crystallinity of conducting polymers, which has been known to be tied to the enhanced electrical conductivity. In this study, we present the new mean of preparing highly crystalline conducting polymers by employing ice as a hard template, where the liquid-like layer on the ice surface offers a new platform to grow conjugated polymer. It was found that crystallinity of conducting polymer can be modulated by changing the temperature of the ice template upon affecting the thickness of the liquid-like layer. The relation of crystallinity and electrical conductivity of ice-templated conducting polymers was quantitatively elucidated. |
Monday, March 5, 2018 1:15PM - 1:27PM |
B52.00009: Tuning Polymer Crystallinity in Polymer Nanocomposites Spiros Anastasiadis, Helen Papananou, Eleni Perivolari, Kyriakh Chrissopoulou Tuning of the degree of crystallinity can be achieved in poly(ethylene oxide)/silica nanohybrids. Silica nanoparticles of different sizes, i.e., smaller, comparable and larger than the polymer radius of gyration were utilized in order to probe the effect of severe confinement on polymer crystallization. The polymer chains under confinement showed different crystallization characteristics with multiple melting transitions and lower degree of crystallinity. Further, mixtures of silica nanoparticle of two different sizes were introduced to enhance chain confinement. Polymer crystallinity can, indeed, be tuned depending on the ratio of large to small nanoparticles for constant polymer concentration. Even systems with zero crystallinity can be obtained for ternary systems where the fraction of large nanoparticle was kept constant and the ratio of the polymer versus small nanoparticles was varied. Acknowledgements: This research has been co-financed by the General Secretariat for Research and Technology (Action KRIPIS, project AENAO, MIS: 5002556). |
Monday, March 5, 2018 1:27PM - 1:39PM |
B52.00010: Gradient and Patterned Polymer Brushes via a Polymer-Single-Crystal-Assisted-Grafting-to Approach Shan Mei, Christopher Li Polymer brushes have been a focus in polymer research due to its potential to tune surface properties and provide a platform to study the tethered chain behavior. Gradient and patterned polymer brushes are of particular interest because they provide a spatially control over the chemical/ physical characteristics of the brush that can be used to systematically study surface structure-property relationship in one simple experiment. In this study, we present a new method to fabricate gradient and patterned polymer brush with predetermined and precisely controlled chain density gradient. Here, a newly discovered self-assembly-assisted-grafting-to approach is utilized where end-functionalized polymers are pre-assembled into two-dimensional polymer single crystals which can be coupled to flat surface to form polymer brushes. Co-crystallization has been utilized to obtain gradient brushes with precisely pre-determined grafting density and gradient pattern. Crystallization behaviors of the gradient brushes have also been systematically investigated. |
Monday, March 5, 2018 1:39PM - 1:51PM |
B52.00011: Thin Film Melt Stability of Cyclic Poly(ε-caprolactone) Giovanni Kelly, Farihah Haque, Scott Grayson, Julie Albert Until recently, studies on semi-crystalline polymers focused on the physical characterization and applications of purely linear or branched polymers. However, synthetic advances have now enabled the production of high purity cyclic polymers using copper catalyzed alkyne-azide click (CuAAC) coupling, thus enabling phenomenological study. In this work, we describe the finding that cyclic poly(caprolactone) resists thin film dewetting better than its linear analogue. A systematic study was conducted to understand this phenomenon on the basis of linear end group chemistry via synthesis of linear PCLs containing triazole groups and terminated with hydroxy, propargyl, azide, and acetyl groups. However, only the cyclic PCL film retained stability in the melt. Ongoing work is focused on further describing the fundamental origin of this stability. GIWAXS and GISAXS experiments will allow us to quantify subtle differences in the crystal lattice as well as the lamellar spacing and orientation relative to the substrate, which may play a role in stability. Developing a better understanding of how chain topology affects thin film stability and using what we learn to enhance the stability of polymers in thin films has the potential for enormous impact on the future of thin film applications. |
Monday, March 5, 2018 1:51PM - 2:03PM |
B52.00012: Calorimetric Study of Crystallization of Polymer Films Formed from Quasi-Vapor Phase Deposition Yucheng Wang, Hyuncheol Jeong, Mithun Chowdhury, Rodney Priestley Owing to the long-chain nature, crystallization and the resulting properties of polymers are dependent on their processing routes. A novel film fabrication method, termed Matrix Assisted Pulsed Laser Evaporation (MAPLE), is employed to investigate the crystallization behavior and thermal properties of model semi-crystalline polymers: poly(ethylene oxide) (PEO) and polyethylene (PE). This enabling technique holds an intrinsic uniqueness in that it features ultra-slow deposition rate, thereby allowing the manipulation of film structure as well as the crystallization of molecules atop a temperature controlled substrate. In this work, the effect of substrate temperature on crystallization of thin PEO/PE films are probed with the aid of fast scanning calorimetry (FSC). Compared with solution casted films, variances sourced from the new approach help to understand the crystallization of PEO/PE films produced by MAPLE deposition. We expect that this ability to tune the crystallization kinetics during polymeric film growth will be enlightening to engineer thin film polymeric-based devices in ways that are difficult by other means. |
Monday, March 5, 2018 2:03PM - 2:15PM |
B52.00013: Study of Molecular Weight Effects on Crystallization Kinetics of Enantiomeric Poly(lactic acid) Blends via Flash DSC Measurement He Yucheng, Pengju Pan, Jiping Wang, Wenbing Hu Abstract: |
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