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Science with the Murchison Widefield Array
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- Judd D. Bowman, Iver Cairns, David L. Kaplan, Tara Murphy, Divya Oberoi, Lister Staveley-Smith, Wayne Arcus, David G. Barnes, Gianni Bernardi, Frank H. Briggs, Shea Brown, John D. Bunton, Adam J. Burgasser, Roger J. Cappallo, Shami Chatterjee, Brian E. Corey, Anthea Coster, Avinash Deshpande, Ludi deSouza, David Emrich, Philip Erickson, Robert F. Goeke, B. M. Gaensler, Lincoln J. Greenhill, Lisa Harvey-Smith, Bryna J. Hazelton, David Herne, Jacqueline N. Hewitt, Melanie Johnston-Hollitt, Justin C. Kasper, Barton B. Kincaid, Ronald Koenig, Eric Kratzenberg, Colin J. Lonsdale, Mervyn J. Lynch, Lynn D. Matthews, S. Russell McWhirter, Daniel A. Mitchell, Miguel F. Morales, Edward H. Morgan, Stephen M. Ord, Joseph Pathikulangara, Thiagaraj Prabu, Ronald A. Remillard, Timothy Robishaw, Alan E. E. Rogers, Anish A. Roshi, Joseph E. Salah, Robert J. Sault, N. Udaya Shankar, K. S. Srivani, Jamie B. Stevens, Ravi Subrahmanyan, Steven J. Tingay, Randall B. Wayth, Mark Waterson, Rachel L. Webster, Alan R. Whitney, Andrew J. Williams, Christopher L. Williams, J. Stuart B. Wyithe
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 30 / 2013
- Published online by Cambridge University Press:
- 16 April 2013, e031
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Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
Contributors
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. Jacob, Arthur James, Maria Jansdotter-Samuelsson, David Jasper, Werner G. Jeanrond, Renée Jeffery, David Lyle Jeffrey, Theodore W. Jennings, David H. Jensen, Robin Margaret Jensen, David Jobling, Dale A. Johnson, Elizabeth A. Johnson, Maxwell E. Johnson, Sarah Johnson, Mark D. Johnston, F. Stanley Jones, James William Jones, John R. Jones, Alissa Jones Nelson, Inge Jonsson, Jan Joosten, Elizabeth Judd, Mulambya Peggy Kabonde, Robert Kaggwa, Sylvester Kahakwa, Isaac Kalimi, Ogbu U. Kalu, Eunice Kamaara, Wayne C. Kannaday, Musimbi Kanyoro, Veli-Matti Kärkkäinen, Frank Kaufmann, Léon Nguapitshi Kayongo, Richard Kearney, Alice A. Keefe, Ralph Keen, Catherine Keller, Anthony J. Kelly, Karen Kennelly, Kathi Lynn Kern, Fergus Kerr, Edward Kessler, George Kilcourse, Heup Young Kim, Kim Sung-Hae, Kim Yong-Bock, Kim Yung Suk, Richard King, Thomas M. King, Robert M. Kingdon, Ross Kinsler, Hans G. Kippenberg, Cheryl A. Kirk-Duggan, Clifton Kirkpatrick, Leonid Kishkovsky, Nadieszda Kizenko, Jeffrey Klaiber, Hans-Josef Klauck, Sidney Knight, Samuel Kobia, Robert Kolb, Karla Ann Koll, Heikki Kotila, Donald Kraybill, Philip D. W. Krey, Yves Krumenacker, Jeffrey Kah-Jin Kuan, Simanga R. Kumalo, Peter Kuzmic, Simon Shui-Man Kwan, Kwok Pui-lan, André LaCocque, Stephen E. Lahey, John Tsz Pang Lai, Emiel Lamberts, Armando Lampe, Craig Lampe, Beverly J. Lanzetta, Eve LaPlante, Lizette Larson-Miller, Ariel Bybee Laughton, Leonard Lawlor, Bentley Layton, Robin A. Leaver, Karen Lebacqz, Archie Chi Chung Lee, Marilyn J. Legge, Hervé LeGrand, D. L. LeMahieu, Raymond Lemieux, Bill J. Leonard, Ellen M. Leonard, Outi Leppä, Jean Lesaulnier, Nantawan Boonprasat Lewis, Henrietta Leyser, Alexei Lidov, Bernard Lightman, Paul Chang-Ha Lim, Carter Lindberg, Mark R. Lindsay, James R. Linville, James C. Livingston, Ann Loades, David Loades, Jean-Claude Loba-Mkole, Lo Lung Kwong, Wati Longchar, Eleazar López, David W. Lotz, Andrew Louth, Robin W. Lovin, William Luis, Frank D. Macchia, Diarmaid N. J. MacCulloch, Kirk R. MacGregor, Marjory A. MacLean, Donald MacLeod, Tomas S. Maddela, Inge Mager, Laurenti Magesa, David G. Maillu, Fortunato Mallimaci, Philip Mamalakis, Kä Mana, Ukachukwu Chris Manus, Herbert Robinson Marbury, Reuel Norman Marigza, Jacqueline Mariña, Antti Marjanen, Luiz C. L. Marques, Madipoane Masenya (ngwan'a Mphahlele), Caleb J. D. Maskell, Steve Mason, Thomas Massaro, Fernando Matamoros Ponce, András Máté-Tóth, Odair Pedroso Mateus, Dinis Matsolo, Fumitaka Matsuoka, John D'Arcy May, Yelena Mazour-Matusevich, Theodore Mbazumutima, John S. McClure, Christian McConnell, Lee Martin McDonald, Gary B. McGee, Thomas McGowan, Alister E. McGrath, Richard J. McGregor, John A. McGuckin, Maud Burnett McInerney, Elsie Anne McKee, Mary B. McKinley, James F. McMillan, Ernan McMullin, Kathleen E. McVey, M. 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Nicholson, George W. E. Nickelsburg, Tatyana Nikolskaya, Damayanthi M. A. Niles, Bertil Nilsson, Nyambura Njoroge, Fidelis Nkomazana, Mary Beth Norton, Christian Nottmeier, Sonene Nyawo, Anthère Nzabatsinda, Edward T. Oakes, Gerald O'Collins, Daniel O'Connell, David W. Odell-Scott, Mercy Amba Oduyoye, Kathleen O'Grady, Oyeronke Olajubu, Thomas O'Loughlin, Dennis T. Olson, J. Steven O'Malley, Cephas N. Omenyo, Muriel Orevillo-Montenegro, César Augusto Ornellas Ramos, Agbonkhianmeghe E. Orobator, Kenan B. Osborne, Carolyn Osiek, Javier Otaola Montagne, Douglas F. Ottati, Anna May Say Pa, Irina Paert, Jerry G. Pankhurst, Aristotle Papanikolaou, Samuele F. Pardini, Stefano Parenti, Peter Paris, Sung Bae Park, Cristián G. Parker, Raquel Pastor, Joseph Pathrapankal, Daniel Patte, W. Brown Patterson, Clive Pearson, Keith F. Pecklers, Nancy Cardoso Pereira, David Horace Perkins, Pheme Perkins, Edward N. Peters, Rebecca Todd Peters, Bishop Yeznik Petrossian, Raymond Pfister, Peter C. Phan, Isabel Apawo Phiri, William S. F. Pickering, Derrick G. Pitard, William Elvis Plata, Zlatko Plese, John Plummer, James Newton Poling, Ronald Popivchak, Andrew Porter, Ute Possekel, James M. Powell, Enos Das Pradhan, Devadasan Premnath, Jaime Adrían Prieto Valladares, Anne Primavesi, Randall Prior, María Alicia Puente Lutteroth, Eduardo Guzmão Quadros, Albert Rabil, Laurent William Ramambason, Apolonio M. Ranche, Vololona Randriamanantena Andriamitandrina, Lawrence R. Rast, Paul L. Redditt, Adele Reinhartz, Rolf Rendtorff, Pål Repstad, James N. Rhodes, John K. Riches, Joerg Rieger, Sharon H. Ringe, Sandra Rios, Tyler Roberts, David M. Robinson, James M. Robinson, Joanne Maguire Robinson, Richard A. H. Robinson, Roy R. Robson, Jack B. Rogers, Maria Roginska, Sidney Rooy, Rev. Garnett Roper, Maria José Fontelas Rosado-Nunes, Andrew C. Ross, Stefan Rossbach, François Rossier, John D. Roth, John K. Roth, Phillip Rothwell, Richard E. 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Stewart, Cynthia Stokes Brown, Ken Stone, Anne Stott, Elizabeth Stuart, Monya Stubbs, Marjorie Hewitt Suchocki, David Kwang-sun Suh, Scott W. Sunquist, Keith Suter, Douglas Sweeney, Charles H. Talbert, Shawqi N. Talia, Elsa Tamez, Joseph B. Tamney, Jonathan Y. Tan, Yak-Hwee Tan, Kathryn Tanner, Feiya Tao, Elizabeth S. Tapia, Aquiline Tarimo, Claire Taylor, Mark Lewis Taylor, Bishop Abba Samuel Wolde Tekestebirhan, Eugene TeSelle, M. Thomas Thangaraj, David R. Thomas, Andrew Thornley, Scott Thumma, Marcelo Timotheo da Costa, George E. “Tink” Tinker, Ola Tjørhom, Karen Jo Torjesen, Iain R. Torrance, Fernando Torres-Londoño, Archbishop Demetrios [Trakatellis], Marit Trelstad, Christine Trevett, Phyllis Trible, Johannes Tromp, Paul Turner, Robert G. Tuttle, Archbishop Desmond Tutu, Peter Tyler, Anders Tyrberg, Justin Ukpong, Javier Ulloa, Camillus Umoh, Kristi Upson-Saia, Martina Urban, Monica Uribe, Elochukwu Eugene Uzukwu, Richard Vaggione, Gabriel Vahanian, Paul Valliere, T. J. 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Yee, Viktor Yelensky, Yeo Khiok-Khng, Gustav K. K. Yeung, Angela Yiu, Amos Yong, Yong Ting Jin, You Bin, Youhanna Nessim Youssef, Eliana Yunes, Robert Michael Zaller, Valarie H. Ziegler, Barbara Brown Zikmund, Joyce Ann Zimmerman, Aurora Zlotnik, Zhuo Xinping
- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
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- 05 August 2012
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- 20 September 2010, pp xi-xliv
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Formation of Polymer Stabilized Ferroelectric Liquid Crystals using a Fluorinated Diacrylate
- C. Allan Guymon, Christopher N. Bowman, Christopher N. Bowman
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- MRS Online Proceedings Library Archive / Volume 559 / 1999
- Published online by Cambridge University Press:
- 10 February 2011, 123
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- 1999
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Ferroelectric liquid crystals (FLCs) have shown great potential for use in electro-optic and display technology due to their inherently fast switching speeds and bistability. Recently, considerable research has been devoted to FLCs mechanically stabilized by a polymer network. The network is formed typically by in situ polymerization of a monomer dissolved in the FLC. Because of the inherent order in the FLC, the polymerization behavior may be significantly different than what might be expected in solution polymerizations. These deviations result largely from the segregation properties of the monomer in the liquid crystal. One class of monomers, namely fluorinated acrylates, is a likely candidate for inducing novel segregation, polymerization and electro-optic behavior in polymer stabilized ferroelectric liquid crystals (PSFLCs). The use of fluorinated moieties has a significant impact on the phase and polymerization behavior of liquid crystal systems. This study focuses on the polymerization of a fluorinated diacrylate, octafluoro 1,6-hexanediol diacrylate (FHDDA), to form PSFLCs and the consequent impact of the polymerization on the ultimate performance. Interestingly, as the temperature is increased and the order of the system decreases, a dramatic increase in the polymerization rate is observed. This increase is especially prominent for polymerizations in the smectic C* phase for which the rate is more than five times that exhibited at much higher temperatures in the isotropic phase. As with other monomer/FLC systems, the segregation of the monomer plays a role in this polymerization behavior as the monomer segregates between the smectic layers of the liquid crystal. The segregation properties also significantly impact the ultimate electro-optic properties. Both ferroelectric polarization and response time of the PSFLC change markedly with different polymerization temperatures, and approach values very close to those of the neat FLC under appropriate polymerization conditions. This behavior not only provides a unique mechanism for rate acceleration in PSFLCs, but also paves the way for new methods to optimize performance in these materials.
Polymerization and Properties of Polymer-Stabilized Ferroelectric Liquid Crystals
- Christopher N. Bowman, C. Allan Guymon
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- MRS Bulletin / Volume 22 / Issue 9 / September 1997
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- 29 November 2013, pp. 15-20
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- September 1997
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The following is based on the presentation made by Christopher N. Bowman, recipient of the MRS Outstanding Investigator Award, at the 1997 MRS Spring Meeting.
I would like to focus on our recent work involving photopolymerizations of monomers in a liquid-crystalline environment. This work is one of the many aspects of photopolymerizations that we are focusing on at the University of Colorado. In particular this effort concentrates on understanding the influence of a liquid-crystalline medium and monomer segregation on polymerization behavior and polymer structure. These studies are of considerable importance for polymer-stabilized ferroelectric liquid crystals (FLCs) because of the enormous potential impact on the area.
I will briefly introduce liquid crystals (LCs), FLCs, and photopolymerizations. I will then discuss the observed electrooptic properties and how these properties change as the LC phase during polymerization is varied. Finally I will address how polymerization kinetics are affected by the LC phase and monomer segregation. This discussion will include results from x-ray diffraction, polarized infrared spectroscopy, and differential scanning calorimetry experiments.
Polymerization Effects on the Electro-Optic Properties of a Polymer Stabilized Ferroelectric Liquid Crystal
- C. Allan Guymon, Lisa A. Dougan, Erik N. Hoggan, Christopher N. Bowman
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- Journal:
- MRS Online Proceedings Library Archive / Volume 425 / 1996
- Published online by Cambridge University Press:
- 10 February 2011, 197
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- 1996
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The introduction of polymeric materials into liquid crystal (LC) matrices has been the focus of much interest in recent years. When a small percentage of polymer network is introduced, the mechanical strength of an LC system increases dramatically without significantly altering the electro-optic properties of the LC. One particular group of LCs, namely, ferroelectric liquid crystals (FLCs), are excellent candidates for such stabilization. FLCs, despite showing great potential for use in electro-optic and display technology due to inherently fast switching times and bistability, have found limited use as they are extremely susceptible to mechanical shock. This study examines the effects of polymerization conditions of a diacrylate monomer in an FLC on its inherent electro-optic properties. The LC phase in which polymerization occurs has a dramatic effect on the polymerization behavior and formation of the polymer network. Such effects have interesting implications on the ferroelectric polarization and switching speed of the FLC. As the temperature of polymerization increases and thus the order of the LC phase decreases, the ferroelectric polarization and the switching time increase.
Studies of a Polymer Dispersed Ferroelectric Liquid Crystal
- C. Allan Guymon, Erik N. Hoggan, Christopher N. Bowman
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- MRS Online Proceedings Library Archive / Volume 377 / 1995
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- 15 February 2011, 865
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- 1995
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Ferrorlrtric liquid crystals (FLCs) have shown great potential for use in electro-optic and display technology due to theri inherently fast switching speeds. Recently within this area a great deal of attention has also been given to FLCs dispersed within a polymer networks. Adding the polymer may act to enhance certain electro-optic properties and will substantially increase the mechanical strenth on the FLC system. This study examines the effects of adding either a diacrylate monomer or a polymer network to a FLC mixture of known composition. The monomer depresses the phase transition temperatures to more orderd phases for both first and second order transitions and causes a marked decrease in the amount of liquid crystal which exhibits typical transitions behavior. During polymerization the network phase separates forming two cocontinuous phases and allows the liquid crystal transitions to return close to values seen in polymer systems. As a result of this decrease, the rotational viscosity decrease for these same samples. Maximum double bond conversions and polymerization rate maxima increase with monomer concentration until saturation on monomer in the liquid crystal is reached. The rate maxima then decreases as the monomer as the monomer must dissolute into the liquid crystal and diffuse to the reactive sites.
Structural Evolution of Highly Crosslinked Polymer Networks
- Kristi S. Anseth, Christopher N. Bowman
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- Journal:
- MRS Online Proceedings Library Archive / Volume 355 / 1994
- Published online by Cambridge University Press:
- 21 February 2011, 65
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- 1994
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Homopolymerizations of multifunctional monomers produce densely crosslinked polymer networks with structures that are often complex and difficult to characterize. The complexity in the structure arises primarily from the heterogeneous nature of the polymerization such as the formation of microgels. This work presents progress towards developing a better understanding of the highly crosslinked polymer structure through combined experimental and modeling techniques. Electron spin resonance (ESR) spectroscopy was used to examine the concentration and local environment of the radicals, i.e., the fraction of radicals that were trapped and terminate on a long time scale as compared to those which are more mobile and terminate on a shorter time scale. A kinetic gelation simulation was developed to verify the ESR results and provide further information regarding the structural evolution of the network and its heterogeneities.
Structural Evolution of Highly Crosslinked Polymer Networks
- Kristi S. Anseth, Christopher N. Bowman
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- Journal:
- MRS Online Proceedings Library Archive / Volume 355 / 1994
- Published online by Cambridge University Press:
- 21 February 2011, 619
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- 1994
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Homopolymerizations of multifunctional monomers produce densely crosslinked polymer networks with structures that are often complex and difficult to characterize. The complexity in the structure arises primarily from the heterogeneous nature of the polymerization such as the formation of microgels. This work presents progress towards developing a better understanding of the highly crosslinked polymer structure through combined experimental and modeling techniques. Electron spin resonance (ESR) spectroscopy was used to examine the concentration and local environment of the radicals, i.e., the fraction of radicals that were trapped and terminate on a long time scale as compared to those which are more mobile and terminate on a shorter time scale. A kinetic gelation simulation was developed to verify the ESR results and provide further information regarding the structural evolution of the network and its heterogeneities.
Effects of Aging on Polymerization Kinetics
- Christopher N. Bowman, Nikolaos A. Peppas
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- Journal:
- MRS Online Proceedings Library Archive / Volume 215 / 1990
- Published online by Cambridge University Press:
- 16 February 2011, 43
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- 1990
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A theoretical model was developed to describe the physical aging during photopolymerizations and crosslinking reactions of diacrylates and dimethacrylates. The model incorporates the strong coupling between the volume relaxation and the kinetics observed in these reactions. Model predictions are presented for the reaction kinetics, volume relaxation, radical concentration and maximum conversion as a function of light intensity and relaxation time of the polymer.