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Liu H, Pojman JA, Zhao Y, Pan C, Zheng J, Yuan L, Horváth AK, Gao Q. Pattern formation in the iodate–sulfite–thiosulfate reaction–diffusion system. Phys Chem Chem Phys 2012; 14:131-7. [DOI: 10.1039/c1cp22281c] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bounds CO, Goetter R, Pojman JA, Vandersall M. Preparation and application of microparticles prepared via the primary amine-catalyzed michael addition of a trithiol to a triacrylate. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/pola.25032] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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53
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Viner V, Pojman JA. Effects of thiols, lithium chloride, and ethoxylated monomers on the frontal polymerization of a triacrylate. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/pola.24914] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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54
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Hu G, Pojman JA, Scott SK, Wrobel MM, Taylor AF. Base-Catalyzed Feedback in the Urea−Urease Reaction. J Phys Chem B 2010; 114:14059-63. [DOI: 10.1021/jp106532d] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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55
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Hu G, Bounds C, Pojman JA, Taylor AF. Time-lapse thiol-acrylate polymerization using a pH clock reaction. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/pola.24088] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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56
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Scognamillo S, Bounds C, Luger M, Mariani A, Pojman JA. Frontal cationic curing of epoxy resins. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/pola.23967] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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57
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Nason C, Pojman JA, Hoyle C. The effect of a trithiol and inorganic fillers on the photo-induced thermal frontal polymerization of a triacrylate. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/pola.23106] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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58
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Marszalek J, Pojman JA, Page KA. Neutron scattering study of the structural change induced by photopolymerization of AOT/D2O/dodecyl acrylate inverse microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:13694-13700. [PMID: 18980349 DOI: 10.1021/la8022634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Small-angle and ultrasmall-angle neutron scattering (SANS/USANS) measurements were used to determine the structural changes induced by photopolymerization of AOT/D2O/(dodecyl acrylate) inverse microemulsion systems. Scattering profiles were collected for the initial microemulsions and the films resulting from photopolymerization of the oil phase. The SANS data for the microemulsions were modeled as spherical, core-shell droplets. Upon polymerization, the clear mircoemulsions formed opaque films. From the SANS/USANS data of the films, it was apparent that this morphology was not preserved upon polymerization; however, it was clearly observed that the formulation of the microemulsion had a large impact on the structure within the films. The Guinier region in the USANS data (2.5 x 10(-5) A(-1) < or = Q < or = 5.3 x 10(-3) A(-1)) from the films indicates that very large structures are formed. Simultaneously, a well-defined peak (0.15 A(-1) < or = Q < or = 0.25 A(-1)) in the SANS data indicates that there are also much smaller structures formed. It is proposed that the low-Q scattering arises from aggregation of the nanometer-size water droplets in the microemulsion to form droplets large enough to scatter visible light, while the peak in the high-Q region results from bilayered structures formed by the surfactant.
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Zhou H, Jiménez Z, Pojman JA, Paley MS, Hoyle CE. Photopolymerization kinetics of tributylmethylammonium-based (meth)acrylate ionic liquids and the effect of water. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/pola.22723] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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60
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Ward M, Yu B, Wyatt V, Griffith J, Craft T, Neurath AR, Strick N, Li YY, Wertz DL, Pojman JA, Lowe AB. Anti-HIV-1 Activity of Poly(mandelic acid) Derivatives. Biomacromolecules 2007; 8:3308-16. [DOI: 10.1021/bm070221y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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61
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Pojman JA, Viner V, Binici B, Lavergne S, Winsper M, Golovaty D, Gross L. Snell's law of refraction observed in thermal frontal polymerization. CHAOS (WOODBURY, N.Y.) 2007; 17:033125. [PMID: 17903007 DOI: 10.1063/1.2784386] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We demonstrate that Snell's law of refraction can be applied to thermal fronts propagating through a boundary between regions that support distinct frontal velocities. We use the free-radical frontal polymerization of a triacrylate with clay filler that allows for two domains containing two different concentrations of a peroxide initiator to be molded together. Because the polymerization reaction rates depend on the initiator concentration, the propagation speed is different in each domain. We study fronts propagating in two parallel strips in which the incident angle is 90 degrees. Our data fit Snell's law v(r)/v(i)=sin theta(r)/sin theta(i), where v(r) is the refracted velocity, v(i) is the incident velocity, theta(r) is the angle of refraction, and theta(i) is the incident angle. Further, we study circular fronts propagating radially from an initiation point in a high-velocity region into a low-velocity region (and vice versa). We demonstrate the close resemblance between the numerically simulated and experimentally observed thermal reaction fronts. By measuring the normal velocity and the angle of refraction of both simulated and experimental fronts, we establish that Snell's law holds for thermal frontal polymerization in our experimental system. Finally we discuss the regimes in which Snell's law may not be valid.
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Zoltowski B, Chekanov Y, Masere J, Pojman JA, Volpert V. Evidence for the existence of an effective interfacial tension between miscible fluids. 2. Dodecyl acrylate-poly(dodecyl acrylate) in a spinning drop tensiometer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:5522-31. [PMID: 17428072 DOI: 10.1021/la063382g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We studied drops of dodecyl acrylate in poly(dodecyl acrylate) (molecular weight of 25,000) in a spinning drop tensiometer to determine whether an effective interfacial tension (EIT) existed between these two miscible fluids. We found convincing evidence. We estimated the mechanical relaxation time from an immiscible analogue (1-propanol and poly(dodecyl acrylate)) and showed that the dodecyl acrylate drops maintained quasi-steady diameters long after this relaxation period. Drops continuously grew in length and became more diffuse, but the width of the transition zone did not grow with t(1/2) as expected from Fick's law although this system had been shown to follow Fick's law in a static configuration (Antrim, D.; Bunton, P.; Lewis, L. L.; Zoltowski, B. D.; Pojman, J. A. J. Phys. Chem. B 2005, 109, 11842-11849). The EIT was determined from Vonnegut's equation, EIT = (Deltarho)omega(2)r(3)/4; both the inner and outer diameters were measured, yielding values of 0.002 and 0.02 mN m(-1), respectively. The EIT was found to be independent of the rotation rate above 6000 rpm and independent of the initial drop volume. The EIT was found to decrease with temperature and increase with the difference in concentration between the monomer drop and polymer-monomer fluid. The square gradient parameter, k, was determined from EIT = k(Deltac(2)/delta), where Deltac is the difference in mole fraction and delta is the width of the transition zone. The square gradient parameter was on the order of 10(-9) N. The square gradient parameter was found to decrease with temperature, to be independent of concentration, and to increase with the molecular weight of the polymer.
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63
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Jiménez Z, Pojman JA. Frontal polymerization with monofunctional and difunctional ionic liquid monomers. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.22030] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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64
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Jiménez Z, Bounds C, Hoyle CE, Lowe AB, Zhou H, Pojman JA. Photopolymerization kinetics of ionic liquid monomers derived from the neutralization reaction between trialkylamines and acid-containing (meth)acrylates. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.22055] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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65
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Chen L, Hu T, Yu H, Chen S, Pojman JA. First solvent-free synthesis of poly(N-methylolacrylamide) via frontal free-radical polymerization. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.22176] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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66
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Chen S, Hu T, Tian Y, Chen L, Pojman JA. Facile synthesis of poly(hydroxyethyl acrylate) by frontal free-radical polymerization. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.21865] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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67
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Mariani A, Alzari V, Monticelli O, Pojman JA, Caria G. Polymeric nanocomposites containing polyhedral oligomeric silsesquioxanes prepared via frontal polymerization. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.22185] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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68
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Marszalek JE, Pojman JA, Aultman KL, Hoyle CE, Whitehead JB. Humidity-responsive polymeric films based on AOT-water reverse microemulsions. J Appl Polym Sci 2007. [DOI: 10.1002/app.26701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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69
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Epstein IR, Pojman JA, Steinbock O. Introduction: Self-organization in nonequilibrium chemical systems. CHAOS (WOODBURY, N.Y.) 2006; 16:037101. [PMID: 17014235 DOI: 10.1063/1.2354477] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The field of self-organization in nonequilibrium chemical systems comprises the study of dynamical phenomena in chemically reacting systems far from equilibrium. Systematic exploration of this area began with investigations of the temporal behavior of the Belousov-Zhabotinsky oscillating reaction, discovered accidentally in the former Soviet Union in the 1950s. The field soon advanced into chemical waves in excitable media and propagating fronts. With the systematic design of oscillating reactions in the 1980s and the discovery of Turing patterns in the 1990s, the scope of these studies expanded dramatically. The articles in this Focus Issue provide an overview of the development and current state of the field.
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Pojman JA, Whitmore C, Turco Liveri ML, Lombardo R, Marszalek J, Parker R, Zoltowski B. Evidence for the existence of an effective interfacial tension between miscible fluids: isobutyric acid-water and 1-butanol-water in a spinning-drop tensiometer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:2569-77. [PMID: 16519456 DOI: 10.1021/la052111n] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We report definitive evidence for an effective interfacial tension between two types of miscible fluids using spinning-drop tensiometry (SDT). Isobutyric acid (IBA) and water have an upper critical solution temperature (UCST) of 26.3 degrees C. We created a drop of the IBA-rich phase in the water-rich phase below the UCST and then increased the temperature above it. Long after the fluids have reached thermal equilibrium, the drop persists. By plotting the inverse of the drop radius cubed (r(-)(3)) vs the rotation rate squared (omega(2)), we confirmed that an interfacial tension exists and estimated its value. The transition between the miscible fluids remained sharp instead of becoming more diffuse, and the drop volume decreased with time. We observed droplet breakup via the Rayleigh-Tomotika instability above the UCST when the rotation rate was decreased by 80%, again demonstrating the existence of an effective interfacial tension. When pure IBA was injected into water above the UCST, drops formed inside the main drop even as the main drop decreased in volume with time. We also studied 1-butanol in water below the solubility limit. Effective interfacial tension values measured over time were practically constant, while the interface between the two phases remains sharp as the volume of the drop declines. The effective interfacial tension was found to be insensitive to changes in temperature and always larger than the equilibrium interfacial tension. Although these results may not apply to all miscible fluids, they clearly show that an effective interfacial tension can exist and be measured by SDT for some systems.
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71
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Binici B, Fortenberry DI, Leard KC, Molden M, Olten N, Popwell S, Pojman JA. Spherically propagating thermal polymerization fronts. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/pola.21246] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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72
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Hu T, Chen S, Tian Y, Pojman JA, Chen L. Frontal free-radical copolymerization of urethane–acrylates. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/pola.21420] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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73
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Evstratova SI, Antrim D, Fillingane C, Pojman JA. Isothermal frontal polymerization: Confirmation of the isothermal nature of the process and the effect of oxygen and polymer seed molecular weight on front propagation. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/pola.21447] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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74
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Lewis LL, DeBisschop CS, Pojman JA, Volpert VA. Isothermal frontal polymerization: Confirmation of the mechanism and determination of factors affecting the front velocity, front shape, and propagation distance with comparison to mathematical modeling. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/pola.21019] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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75
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McFarland B, Popwell S, Pojman JA. Free-Radical Frontal Polymerization with a Microencapsulated Initiator: Characterization of Microcapsules and Their Effect on Pot Life, Front Velocity, and Mechanical Properties. Macromolecules 2005. [DOI: 10.1021/ma051661p] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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