Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session R11: Polymer Crystallization Under ConfinementFocus
|
Hide Abstracts |
Sponsoring Units: DPOLY Chair: George Floudas, University of Ioannina Room: 270 |
Thursday, March 16, 2017 8:00AM - 8:36AM |
R11.00001: Correlating Polymer Crystals via Self-Induced Nucleation Invited Speaker: G\"{u}nter Reiter Crystallizable polymers often form multiple stacks of uniquely oriented lamellae, which have good registry despite being separated by amorphous fold surfaces. These correlations require multiple synchronized, yet unidentified, nucleation events. Here, we demonstrate that in thin films of isotactic polystyrene, the probability of generating correlated lamellae is controlled by the branched morphology of a single primary lamella. The nucleation density $n_s$ of secondary lamellae is found to be dependent on the width of the branches of the primary lamella. This relation is independent of molecular weight, crystallization temperature, and film thickness. We propose a nucleation mechanism based on the insertion of polymers into a branched primary lamellar crystal. Even in single crystals, characterized by faceted structures with a well-defined envelope reflecting the underlying crystal unit cell, polymers are folded and thus in a meta-stable state. Annealing such meta-stable single crystals allowed to unveil the initial morphological framework of a dendritic single crystal, i.e. the initial stages of growth. [Preview Abstract] |
Thursday, March 16, 2017 8:36AM - 8:48AM |
R11.00002: Precisely Branched Polyethylene: Effect of Alkyl Branch Size on Nanoscale Morphology Ingo Lieberwirth, Kenneth Wagener, Bora Inci, Haixin Zhou Morphological characterization is reported for a series of precisely branched polyethylene structures, the branch being placed on every 20$^{st}$ or 38$^{th}$ carbon and varying in size from methyl to pentadecyl group and additionally with the introduction of phosphate and phosphonate groups. The morphology and physical properties of the crytallized polymer were investigated using DSC, x-ray scattering and TEM. Precise branching significantly reduces the melting point and lamellaer thickness. On the other hand, all further branches from ethyl to pentadecyl produce polymers that have similar melting points. A polyethylene with short branches at precisely every 38th unit will incorporate these defects into the crystal. Structural analysis reveals, that the packing perpendicular to the main chain axis is of orthorhombic PE type with an increase of lattice parameters. The appearance of the (00l) spots, on the other hand, gives rise to assume a much higher disorder of crystal structure in direction of the molecular backbone. [Preview Abstract] |
Thursday, March 16, 2017 8:48AM - 9:00AM |
R11.00003: Overall Isothermal Crystallization Kinetics of Precision Polyethylenes with Bromine in a Wide Temperature Range Xiaoshi Zhang, Wei Zhang, Emine Boz, Kenneth B Wagener, Rufina G Alamo The overall crystallization kinetics of the two major polymorphs of a series of polyethylenes with bromine atoms precisely placed on each and every 9$^{\mathrm{th}}$, 15$^{\mathrm{th}}$, and 21$^{\mathrm{st}}$ backbone carbon have been studied by real time FTIR with parallel morphological studies by polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). The crystallization kinetics are unusual due to the presence of two inversions in the temperature coefficient of the overall crystallization rate. The low temperature inversion takes place in a temperature range where the two polymorphs coexist, and the second, high temperature inversion is found in a temperature range where only Form II can develop. The mechanism that leads to this unusual behavior will be discussed. [Preview Abstract] |
Thursday, March 16, 2017 9:00AM - 9:12AM |
R11.00004: Effect of chain topology on crystallization within nanoporous alumina. Yang Yao, Yasuhito Suzuki, Takamasa Sakai, Jan Seiwert, Holger Frey, Martin Steinhart, Hans-Juergen Butt, George Floudas Polymer topology has inevitable influence on the structure, packing, and dynamic of chains. Herein, we investigate for the first time the impact of polymer architecture on crystallization under 2D confinement, the latter provided by nanoporous alumina (AAO). We employ two poly(ethylene oxide) (PEO) star polymers to study the effect of (i) end groups and (ii) molecular weight on polymer crystallization in the bulk and under confinement. Bulk end groups reduce the crystallization/melting temperatures and the corresponding equilibrium melting point. Under confinement, in the absence of catalyst, homogeneous nucleation prevails as with linear PEOs. The homogeneous nucleation temperatures for the star polymers agree with that of linear ones provided that the arm molecular weight is used instead. Long-range dynamics pertinent to star relaxation are affecting the homogeneous nucleation temperature. On the other hand, the segmental dynamics speed up on confinement. In addition to star PEO, we study the effect of another topology, i.e. hyperbranched PEO, on the nucleation mechanism. [Preview Abstract] |
Thursday, March 16, 2017 9:12AM - 9:24AM |
R11.00005: Effects of polydispersity, additives, and impurities on the crystallization of semi-crystalline polymers confined to nanoporous alumina Yasuhito Suzuki, Martin Steinhart, Hans-Jürgen Butt, George Floudas Polymers crystallize via \textit{heterogeneous} nucleation at impurities or via \textit{homogeneous} nucleation with the intrinsic mechanism. While the concept has long been known, the detailed mechanisms of both \textit{heterogeneous} and \textit{homogeneous} nucleation still remain elusive. Recent experiments showed that the nucleation mechanisms of semi-crystalline polymers transform from \textit{heterogeneous} to \textit{homogeneous} nucleation under confinement to self-orderd nanoporous alumina (AAO) with a diameter of \textasciitilde 65 nm. We further investigated the effect of polydispersity, additives, impurities and surfaces on the nucleation mechanism under confinement with the aim to better understand the origin of \textit{heterogeneous} and of \textit{homogeneous} nucleation. We found that the \textit{homogeneous} nucleation shifts to a lower temperature by an addition of oligomer. The shift of the nucleation temperature correlates to the shift of liquid to glass temperature due to the plasticizing effect of the oligomer. The result implies the relation of \textit{homogeneous} nucleation to liquid-to-glass temperature. On the other hand, it turned out that addition of other polymers, changing polydispersity, and the roughness of AAO do not initiate \textit{heterogeneous} nucleation at all when the polymer is confined to small pores with a diameter below 35 nm. [Preview Abstract] |
Thursday, March 16, 2017 9:24AM - 9:36AM |
R11.00006: Functional Polymer Crystallization in Cylindrical Pores Aurora Nogales, Jaime Martin Crystallization of polymers confined to nanoscopic cavities is attracting increasing interest as tool to deal with classical problems of the crystallization process, such as the early stages of the liquid−solid transformation or the nature of the crystal growth-front, as both processes seem to be size dependent. At the same time , these investigations are essential to achieve nanostructures with optimal properties due to the fact that their mechanical, optical, transport, or ferroelectric properties depend to a large extent on the crystalline characteristics of the nanostructure, i.e., the crystallinity, the polymorph, the crystal size, the crystal orientation, the defects, and so on. In this context, the system composed of polymers confined into anodic aluminum oxide (AAO) nanopore arrays is standing out due to a high tunability on the degree of confinement in terms of the pore diameter, a mechanical rigidity of the hard pore walls, and a well-defined confining geometry. In this contribution we discussed on the effect of confinement on the crystallization of functional polymers in AAO nanopores, like P3HT, PVDF-TrFE and PFO, and the modification of their functionality due to crystallization under confinement. [Preview Abstract] |
Thursday, March 16, 2017 9:36AM - 9:48AM |
R11.00007: Polymer crystallization in gratings prepared by Nanoimprint Lithography as revealed by Atomic Force Microscopy and Grazing Incidence X-ray Scattering T. A. Ezquerra, M. Soccio, D.E. Martinez-Tong, N. Alayo, M.C. Garcia-Gutierrez, F. Perez-Murano, N. Lotti, A. Munari Nanostructured gratings of semicrystalline polymers like poly(propylene azelate) (PPAz) or of ferroelectric copolymers of vinylidene fluoride(VDF) and trifluoroethylene(TrFE) have been prepared over spin-coated thin films by Nanoimprint Lithography (NIL). The structure and morphology of the gratings have been investigated by combining Atomic Force Microscopy (AFM) and Grazing Incidence X-ray Scattering at small angle (GISAXS) and wide angle (GIWAXS). The results reveal that NIL affects significantly the orientation of the crystalline lamellae. In both cases gratings are more abundant in edge-on lamellae than the reference non-printed films. For PPAz we attribute this effect to the preferential crystallization as flat-on lamellae on silicon surfaces either the stamp trench walls or the substrate surface. Thus, the flat-on lamellae on the trench walls appear to be edge-on lamellae in the printed sample. These results further support NIL as an appropriate procedure in order to control polymer crystal orientation. [Preview Abstract] |
Thursday, March 16, 2017 9:48AM - 10:00AM |
R11.00008: Polymer Crystallization in Nanoparticles Aurora Nogales, Jing Cui, Daniel Martinez-Tong, Tiberio A Ezquerra Crystallizable polymers confined into nanodroplets and nanoparticles can serve as starting point in order to prepare nanocrystals with specific functionalities. In addition, They can help to better understand the effect of confinement on the mechanisms of crystal nucleation and growth. As compared to other confining geometries, nanoparticles offer the advantage of providing a 3D confinement, without any preferential direction that may act as template. Also, nanoparticles offer a versatile geometry that enables the possibility of tuning the interaction with the confinement media. An example of this can be the differences among free standing particles or those embedded either in soft or in rigid media. In this contribution we present results on the crystallization of selected conducting and ferroelectric polymers in nanoparticles prepared by miniemulsion and flash precipitation. Results suggest that the polymers crystallized in these geometries present metastable configuration that enhance the presence of mesophases not present in the bulk. The implication of this effect on the physical properties will be discussed. [Preview Abstract] |
Thursday, March 16, 2017 10:00AM - 10:12AM |
R11.00009: Confined and directed polymer crystallization at liquid/liquid interface. Christopher Li, Hao Qi, Mark Staub A curved space is intrinsically incommensurate with 3D translational symmetry. In this presentation, we will discuss the growth and structure of polymer single crystals confined in and directed by curved liquid/liquid interface using a miniemulsion crystallization method. We will use the name ``crystalsome'' to describe this unique structure because they are formed by polymer lamellar crystals and their structure mimics liposomes and polymersomes. Crystal structure and polymer chain packing have been systematically investigated using electron diffraction and wide angle X-ray diffraction. It has been found that the crystallinity and crystallite sizes are significantly affected by the radius of curvature. Atomic force microscopy measurement demonstrated a two ? three orders of magnitude increase in bending modulus compared with conventional polymersomes. [Preview Abstract] |
Thursday, March 16, 2017 10:12AM - 10:24AM |
R11.00010: Polymer Deposition from a Quasi-Vapor Phase as a New Route to Access a Wide Temperature Range for Crystallization Hyuncheol Jeong, Craig Arnold, Rodney Priestley Polymer crystallization is strongly governed by kinetics where crystallization temperature (Tc) plays an important role in determining materials properties. Due to the high entropic barrier required for reorganization, the long-chain molecules typically form folded-chain crystals, whose thickness and thermal stability decrease as Tc is lowered. Interesting questions remain regarding crystallization in the deeply supercooled regime. This is partially due to the difficulty in accessing the low Tc range without nucleation. For a strong crystal-former like polyethylene (PE), cooling from a melt or solution always confronts the onset of nucleation at a high Tc followed by rapid crystal growth. Here, we introduce an alternative approach to grow polymer crystals via Matrix Assisted Pulsed Laser Evaporation (MAPLE). This methodology achieves the crystallization of polymers from a quasi-vapor phase at a controlled temperature, allowing for the study of the empirical relationship between Tc and crystal structure over a wide range of Tc. With PE as a model polymer, we investigated the morphological and thermal properties of crystals grown over a wide temperature range down to 120 °C below bulk crystallization point. [Preview Abstract] |
Thursday, March 16, 2017 10:24AM - 10:36AM |
R11.00011: Interface & confinement induced order and orientation in thin films of Poly-Caprolactone Kossack Wilhelm, Anne Seidlitz, Thomas Thurn-Albrecht, Friedrich Kremer Infrared-transition moment orientational analysis (IR-TMOA), X-ray Diffraction (XRD) measurements and model calculations are combined to study interface and confinement induced order and orientation in thin ($h=11\mu$m) films of Poly-caprolactone (PCL) prepared by drop-casting on silicon wafers. Depending on the crystallization temperature, 303K <$T_x$< 333K, spherulites with a diameter of 1$\mu$m<$d_S$<500$\mu$m form. Macroscopic order of the crystalline lamellae is imposed by spatial confinement ($d_S>h$) and interfacial interactions and quantified by IR-TMOA and XRD pole figures. Both techniques rely on the relative orientation of sample and incident radiation, and measure, in case of PCL, the orientation distribution of complementary crystal directions. This allows to (1) correlate the directions of the transition moments with the crystal axes; and (2) estimate the volume fractions of flat- or edge on lamellae as induced by the different interfaces, as well as the fractions of surface-induced- or bulk-nucleated spherulites in dependence on $T_x$. The contribution of substrate induced spherulitic structures rises with $T_x=323$ K up to $\sim12$vol\%, whereas no indications of edge on lamellae at the free surface are found. At $T_x\leq313$K the bulk phase dominates. [Preview Abstract] |
Thursday, March 16, 2017 10:36AM - 10:48AM |
R11.00012: Ultrathin film crystallization of poly($\epsilon$-caprolactone) in blends containing styrene-isoprene block copolymers: the nano-rose morphology Giovanni Kelly, Julie Albert Semi-crystalline polymers have been studied for decades due to unique physical, optical, and chemical properties that make them attractive materials for packaging, opto-electronics, and tissue engineering. While the thin film morphologies of semi-crystalline polymers have been well-studied for decades, blending with other crystalline and amorphous polymers and copolymers continues to provide new insights on crystal growth and morphology control. Blending can also lead to the discovery of novel, useful crystalline morphologies. This work discusses the discovery and investigation of what we refer to as the “nano-rose” morphology. The nano-rose morphology is a relatively monodisperse collection of 500 nanometer diameter crystalline spirals, exceptionally different from both the crystalline and blend morphologies typically observed in ultrathin films. Non-conventional crystal growth in the form of lamellar scrolling, twisting, and s-shaped and c-shaped crystals has been noted previously by others. Through a systematic study of variables that dictate morphology in ultrathin films, our results complement those findings and reinforce the hypothesis that unbalanced surface stresses acting on growing crystalline lamellae cause polymer crystals to grow in an unconventional matter. [Preview Abstract] |
Thursday, March 16, 2017 10:48AM - 11:00AM |
R11.00013: Crystal Thickening in Strongly Segregated Crystalline-Amorphous Diblock Copolymers Adam B. Burns, Richard A. Register In semicrystalline-amorphous diblock copolymers the phase behavior and structure are determined by the complex interplay between crystallization and block incompatibility. If the segregation strength is sufficiently high in the melt, crystallization can be confined by the amorphous domains. Strongly segregated, lamellar diblocks containing semicrystalline hydrogenated polynorbornene (hPN) have been studied. Wide-angle x-ray scattering patterns of flow-aligned specimens indicate that the crystal stems lie generally parallel to the domain interfaces. This arrangement avoids incommensurability between the crystal thickness and the domain periodicity. Small-angle x-ray scattering reveals that, although the amorphous block is rubbery when hPN crystallizes, the orientation of the lamellar microdomains is maintained upon crystallization, confirming that the crystals are confined to the hPN microdomains. While the microdomain morphology remains intact, there is a measurable increase in the domain periodicity upon crystallization caused by crystal growth normal to the domain interface. Differential scanning calorimetry is used to show that the confined crystals thicken towards an equilibrium crystal thickness (melting point) when annealed near the melting point. Unlike the homopolymer, where the equilibrium structure is the extended chain crystal, one end of the hPN block (i.e., the block junction) must remain anchored to the microdomain interface, and the concomitant chain stretching at the interface limits the crystal thickness. Furthermore, the limiting crystal thickness increases with increasing molecular weight. [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