Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session W20: Focus Session: Membranes and Confinement |
Hide Abstracts |
Sponsoring Units: DPOLY Chair: Pullickel Ajayan, Rice University Room: 405 |
Thursday, March 6, 2014 2:30PM - 2:42PM |
W20.00001: Poly(styrene-b-dimethylsiloxane-b-styrene) Membranes in Pervaporation for In Situ Product Recovery during Fermentation Chaeyoung Shin, Zachary Baer, Ali Evren Ozcam, Douglas Clark, Nitash Balsara In situ product recovery was investigated in fermentation experiments to enable the development of a continuous fermentation process. Our pervaporation membranes are based on poly(styrene-b-dimethylsiloxane-b-styrene) (SDS) block copolymers. Polydimethylsiloxane (PDMS) is the best known organophilic pervaporation membrane material and was utilized as the transporting phase for selective permeation of organic molecules. The polystyrene (PS) block added structural integrity to the membrane due to the high modulus of PS. SDS membranes were found to have both the enhanced robustness as well as comparable pervaporation performance to that of cross-linked PDMS membranes. The permeabilities of water and organic components through SDS membranes were studied to elucidate the sorption and transport phenomena in this system. Furthermore, experiments combining fermentation with pervaporation were performed, and continuous fermentation by using pervaporation as the sole means of removing products was successfully demonstrated for the first time. [Preview Abstract] |
Thursday, March 6, 2014 2:42PM - 2:54PM |
W20.00002: Microphase Separated Block Copolymers in Pervaporation Membranes for Biofuels Processing Douglas Greer, Chae-Young Shin, Evren Ozcam, Jeffrey Skerker, Thalita Basso, Dacia Leon, Stefan Bauer, Nitash Balsara The production of transportation biofuels requires numerous continuous separation processes. We designed block copolymer membranes for pervaporation as a means to achieve these separations. These block copolymers contain a glassy structure block for support and a rubbery transport block for sorption and diffusion. We create membranes with nanoscale conducting channels using the unique trait of block copolymers to assemble into ordered morphologies. We have previously used nanostructured membranes to separate ethanol/water binary mixtures [J. Membr. Sci. 373, 112 (2011)], [J. Membr. Sci. 401, 125 (2012)]. We report this type of membranes is effective in other, more complex separations important to biofuel production. These separations increase yield and decrease process time. [Preview Abstract] |
Thursday, March 6, 2014 2:54PM - 3:06PM |
W20.00003: Controlling Solution Self-assembly and Non-Solvent Induced Microphase Separation of Triblock Terpolymers to Generate Nanofiltration Membranes with Chemically-Tailored Pore Walls Bryan Boudouris, Ryan Mulvenna, Jacob Weidman, William Phillip Block polymer-based templates have been utilized in a number of membrane applications; however, there has yet to be a demonstration of a nanoporous block polymer thin film that can achieve high flux and high selectivity simultaneously while also allowing for the facile tuning of the pore wall chemistry. Here, we demonstrate that by synthesizing and controlling the solution self-assembly of a triblock terpolymer, polyisoprene-$b$-polystyrene-$b$-poly($N$,$N$-dimethylacrylamide) (PI-PS-PDMA), and precisely inducing non-solvent induced phase separation during the self-assembly process allows for the creation of an asymmetric nanoporous membrane with PDMA-lined pore walls. This PDMA functionality is then converted to any number of side chain functionalities through simple chemistry in the solid state. In this way, we are able to show a highly selectivity membrane that can separate analytes of interest based both on size and chemical composition at a high solution flux. In fact, this high fidelity structure has a very narrow distribution of pore sizes (\textless 10{\%} variation in diameter) over large areas (\textgreater 500 cm$^{\mathrm{2}})$. This has allowed for the separation of particles with hydrodynamic radii as low as 0.8 nm, which is the smallest separation achieved using a block polymer-based membrane to date. [Preview Abstract] |
Thursday, March 6, 2014 3:06PM - 3:42PM |
W20.00004: N/A Invited Speaker: Ramanan Krishnamoorti |
Thursday, March 6, 2014 3:42PM - 3:54PM |
W20.00005: Mechanical Properties of Two-Dimensional Alkanethiol-Coated Gold Nanoparticle Membranes K. Michael Salerno, Dan S. Bolintineanu, J. Matthew D. Lane, Gary S. Grest Membranes formed from nanoparticle monolayers have been shown to have mechanical properties that may make them suitable for use in micro-scale devices. Metallic-core nanoparticles with short, organic ligands can form membranes with dimensions up to several micrometers, with large elastic moduli. Experimental tests of membranes with different cores and ligands indicate that ligand length as well as core-ligand and ligand-ligand interactions can influence membrane mechanical response. We use explicit-atom molecular dynamics simulations to examine the properties of membranes formed from a two-dimensional hexagonal array of alkanethiol-coated Au nanoparticles. Results are presented for nanoparticle core diameters from 4-6nm, ligand lengths of 10-18 units and carboxyl and methyl end groups, all of which influence the mechanical properties of the membranes. Knowledge of how microstructure and composition influence membrane properties could lead to efficient membrane manufacture with improved mechanical properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Thursday, March 6, 2014 3:54PM - 4:06PM |
W20.00006: Nanoparticle Encapsulation in Diblock Copolymer/Homopolymer Blend Thin Film Mixtures Junnan Zhao, Xi Chen, Peter Green We investigated the organization of low concentrations of poly (2-vinylpyridine) (P2VP) grafted gold nanoparticles within a diblock copolymer polystyrene-b-poly (2-vinylpyridine) (PS-b-P2VP)/homopolymer polystyrene (PS) blend thin film. The PS-b-P2VP copolymers formed micelles, composed of inner cores of P2VP block and outer coronae of PS blocks, throughout the homopolymer PS. All nanoparticles were encapsulated within micelle cores and each micelle contained one or no nanoparticle, on average. When the host PS chains are much longer than corona chains, micelles tended to self-organize at the interfaces. Otherwise, they were dispersed throughout the PS host. In comparison to the neat PS-b-P2VP/PS blend, the nanoparticles/PS-b-P2VP/PS system had a higher density of smaller micelles, influenced largely by the number of nanoparticles in the system. The behavior of this system is understood in terms of the maximization of the nanoparticle/micelle core interactions and of the translational entropies of the micelles and the nanoparticles. [Preview Abstract] |
Thursday, March 6, 2014 4:06PM - 4:18PM |
W20.00007: Bicontinuous Porous Carbon Films Templated with ABC Triblock Copolymers Kevin Cavicchi, Guodong Deng, Bryan Vogt Mesoporous carbons are useful for a range of applications such as separation and catalysis. A route to prepare porous materials is through cooperative self-assembly of a carbon precursor (e.g. phenolic resin) and a block copolymer, in which the precursor is selectively soluble, to drive mesophase formation. Typical soft templating uses AB or ABA block copolymers, which form classical morphologies, such as spheres, cylinders, and lamellae. Switching to an ABC type block copolymer provides greater flexibility in the design of the morphology potentially opening up larger processing windows for complex structures, such as bicontinuous morphologies. This presentation will discuss efforts to prepare bicontinuous porous carbon thin films using an ABC triblock copolymer of poly(ethylene oxide)-block-poly(ethyl acrylate)-block-polystyrene via spin-coating and a series of thermal annealing steps. It will be shown that direct thermal annealing can produce high porosity ($\sim$60\%) carbon fiber networks. In addition, adding a solvent annealing step prior to the thermal annealing steps is able to produce longer range order structures with a small window of an ordered bicontinuous morphology. These high porosity films with organized fibers are promising for energy and separation applications. [Preview Abstract] |
Thursday, March 6, 2014 4:18PM - 4:54PM |
W20.00008: Crystallization and Phase Transitions in Polymer Nanolayered Systems under Confinement Invited Speaker: Eric Baer Forced assembly multiplication coextrusion has been reported as an advanced technique to study crystallization and phase transitions for polymers under confinement. This technique can readily produce continuous alternating layered structures composed of two or three polymers [1, 2]. Multilayer films fabricated by multiplication coextrusion consist of hundreds or thousands of layers with individual layer thickness varying from 10 nanometers to several micrometers. The flexibility of this novel multiplication coextrusion process, particularly at the nanoscale, enables the study of confinement effects on polymer crystallization and phase transitions. We have discovered that the hierarchical morphology of many polymers can be manipulated by confinement between rigid layers [2]. Spherulites are flattened and lamella single crystals are oriented as the confining scale is decreased towards the nano-level. Poly(ethylene oxide) (PEO), poly($\varepsilon $-caprolactone) (PCL), syndiotactic polypropylene (sPP) and poly(vinylidene fluoride) (PVDF) will be given as unique examples of this phenomena [2, 3]. Depending on the crystallization temperature, two major lamellae orientations ``in-plane'' or ``on-edge'' can be achieved, which dramatically affect the multilayer film characteristics, such as film barrier properties [2, 4].For some polymers such as high density polyethylene (HDPE), in-plane lamellae orientation is difficult to achieve. However, at the micro-scale, confined HDPE spherulites have tilted lamellae, which also improve gas barrier properties. Nanoscale multilayer films were also utilized to produce submicron size polymer droplets by thermal breakup of the layers [4]. Phase transitional behaviors during fractionated crystallization of these droplets will be described as a powerful tool for the study of both heterogeneous and homogeneous nucleation. \\[4pt] [1] M. Ponting, A. Hiltner and E. Baer, Macromolecular Symp, 294(2010), 19 -32.\\[0pt] [2] J. l M. Carr, D.S. Langhe, M. T. Ponting, A. Hiltner, and E. Baer, J. Mater. Res, 27(2012), 1326-1350.\\[0pt] [3] J. M. Carr, M. Mackey, L. Flandinb, A. Hiltner and E. Baer, Polymer, 54(2013), 1679--1690.\\[0pt] [4] D.S. Langhe, A. Hiltner and E. Baer, Polymer, 52(2011), 5879--5889. [Preview Abstract] |
Thursday, March 6, 2014 4:54PM - 5:06PM |
W20.00009: Estimation of the Thickness of the Interface in Polyoctenamer-Single Walled Carbon Nanotube Composites by Thermogravimetric Analysis Alin Cristian Chipara, Robert Vajtai, Pulickel M. Ajayan, Dorina M. Chipara, Elamin Ibrahim, James Hinthorne, Mircea Chipara In polymer-based nanocomposites, macromolecular chains surround the nanoparticles interacting with them and thus defining a thin layer of material known as interface. The interface exhibits modified physical properties compared to the polymeric matrix; shifts of the glass, melting, and crystallization temperatures. A simple method for the estimation of the thickness of the interface in polymer based nanocomposites, by using thermogravimetric analysis is presented. The method is exemplified through experimental data on polyoctenamer-single walled carbon nanotube nanocomposites obtained by melt mixing. The thermal stability of the as obtained nanocomposites has been investigated by thermogravimetric analysis, using a Q50 TGA instrument from TA Instruments. The measurements have been performed in air and in nitrogen atmosphere at various heating rates (5, 10, 20, 30, and 40 $^{o}$C/min). Additional measurements by Raman, and Wide Angle X Ray are supporting thermal analysis data. [Preview Abstract] |
Thursday, March 6, 2014 5:06PM - 5:18PM |
W20.00010: Programmable Crafting of Hierarchically Structured Block Copolymer/Nanoparticles (and Nanorods) via Flow Enabled Self-Assembly Zhiqun Lin, Bo Li, Wei Han Hierarchical assembly of diblock copolymer/nanocrystals (e.g., Au and CdSe nanoparticles and nanorods) was successfully crafted into parallel stripes by flow enabled self-assembly (FESA). They were precisely and programmably patterned at desired position on the substrate. Remarkably, a minimum spacing between two adjacent stripes was observed and a model was proposed to understand the relationship between the width of stripes and the minimum spacing. FESA of diblock copolymer/nanocrystals is a lithography-free method and facile to implement, offering opportunities for creating functional hierarchically structured materials and devices. [Preview Abstract] |
Thursday, March 6, 2014 5:18PM - 5:30PM |
W20.00011: On the Glass Transition in Polystyrene-TiO2 Nanocomposites Jorge Alarcon, Dorina M. Chipara, Karen Lozano, Mircea Chipara, Alin Cristian Chipara, Robert Vajtai, Pulickel M. Ajayan Nanocomposites of atactic polystyrene (PS) filled with TiO2 nanoparticles of about 15 nm have been prepared. A dilute solution of PS in a good solvent (chlorophorm) has been prepared by stirring the components at room temperature for 24 h at 500 rotations per minute. The solution was then sonicated for 5 minutes by using a high power sonicator. TiO2 nanoparticles were added in the sonicating bath and the sonication continued for 1 hour in order to achieve an uniform dispersion on nanoparticles. Then, a non solvent (distilled water) has been suddenly added under sonication. The sonication continued for about 30 minutes. After 30 minutes, the polymer nanocomposite was isolated from the liquid mixture by filtration. The residual amount of solvent and water was removed by placing the nanocomposites into a vacuum oven at 100 C for 12 hours. The complete removel of water and solvent was confirmed by TGA. The as obtained samples were measured by Differential Scanning Calorimetry and the effect of TiO2 on the glass transition temperature was investigated. The effect of TiO2 on the glass transition of PS is discussed. [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