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Cui Y, Li MC, Wu Q, Pojman JA, Kuroda DG. Synthesis-Free Phase-Selective Gelator for Oil-Spill Remediation. ACS APPLIED MATERIALS & INTERFACES 2017; 9:33549-33553. [PMID: 28895716 DOI: 10.1021/acsami.7b10009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A new deep eutectic solvent (DES) was developed as a phase-selective gelator for oil-spill remediation. The newly designed nonionic DES is based on a combination of an amide (N-methylacetamide) and a long chain carboxylic acid (lauric acid) and does not require any synthetic procedure besides mixing. Our studies show that the DES works as gelator by forming a gel between lauric acid and the hydrocarbon, whereas the amide serves to form the DES and dissolves in water during the gelation process. In addition, the DES material has gelation properties comparable to those considered as state-of-the-art. Overall, the newly developed material shows a promising future in oil recovery methodologies.
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Viner G, La Monica T, Lombardo R, Pojman JA. Effect of pseudo-gravitational acceleration on the dissolution rate of miscible drops. CHAOS (WOODBURY, N.Y.) 2017; 27:104603. [PMID: 29092439 DOI: 10.1063/1.4990069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The effect of pseudo-gravitational acceleration on the dissolution process of two phase miscible systems has been investigated at high acceleration values using a spinning drop tensiometer with three systems: 1-butanol/water, isobutyric acid/water, and triethylamine/water. We concluded that the dissolution process involves at least three different transport phenomena: diffusion, barodiffusion, and gravitational (buoyancy-driven) convection. The last two phenomena are significantly affected by the centrifugal acceleration acting at the interface between the two fluids, and the coupling with the geometry of the dissolving drop leads to a change of the mass flux during the course of the dissolution process.
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Bunton PH, Tullier MP, Meiburg E, Pojman JA. The effect of a crosslinking chemical reaction on pattern formation in viscous fingering of miscible fluids in a Hele-Shaw cell. CHAOS (WOODBURY, N.Y.) 2017; 27:104614. [PMID: 29092415 DOI: 10.1063/1.5001285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Viscous fingering can occur in fluid motion whenever a high mobility fluid displaces a low mobility fluid in a Darcy type flow. When the mobility difference is primarily attributable to viscosity (e.g., flow between the two horizontal plates of a Hele-Shaw cell), viscous fingering (VF) occurs, which is sometimes termed the Saffman-Taylor instability. Alternatively, in the presence of differences in density in a gravity field, buoyancy-driven convection can occur. These instabilities have been studied for decades, in part because of their many applications in pollutant dispersal, ocean currents, enhanced petroleum recovery, and so on. More recent interest has emerged regarding the effects of chemical reactions on fingering instabilities. As chemical reactions change the key flow parameters (densities, viscosities, and concentrations), they may have either a destabilizing or stabilizing effect on the flow. Hence, new flow patterns can emerge; moreover, one can then hope to gain some control over flow instabilities through reaction rates, flow rates, and reaction products. We report effects of chemical reactions on VF in a Hele-Shaw cell for a reactive step-growth cross-linking polymerization system. The cross-linked reaction product results in a non-monotonic viscosity profile at the interface, which affects flow stability. Furthermore, three-dimensional internal flows influence the long-term pattern that results.
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Kondepudi D, Petrosky T, Pojman JA. Dissipative structures and irreversibility in nature: Celebrating 100th birth anniversary of Ilya Prigogine (1917-2003). CHAOS (WOODBURY, N.Y.) 2017; 27:104501. [PMID: 29092431 DOI: 10.1063/1.5008858] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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30
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Carranza A, Pérez-García MG, Song K, Jeha GM, Diao Z, Jin R, Bogdanchikova N, Soltero AF, Terrones M, Wu Q, Pojman JA, Mota-Morales JD. Deep-Eutectic Solvents as MWCNT Delivery Vehicles in the Synthesis of Functional Poly(HIPE) Nanocomposites for Applications as Selective Sorbents. ACS APPLIED MATERIALS & INTERFACES 2016; 8:31295-31303. [PMID: 27779385 DOI: 10.1021/acsami.6b09589] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report an alternative green strategy based on deep-eutectic solvents (DES) to deliver multiwalled carbon nanotubes (MWCNTs) for a bottom-up approach that allows for the selective interfacial functionalization of nonaqueous poly(high internal phase emulsions), poly(HIPEs). The formation and polymerization of methacrylic and styrenic HIPEs were possible through stabilization with nitrogen doped carbon nanotube (CNX) and surfactant mixtures using a urea-choline chloride DES as a delivering phase. Subtle changes in CNX concentration (less than 0.2 wt % to the internal phase) produced important changes in the macroporous monolith functionalization, which in turn led to increased monolith hydrophobicity and pore openness. These materials displayed great oleophilicity with water contact angles as high as 140° making them apt for biodiesel, diesel, and gasoline fuel sorption applications. Overall, styrene divinylbenzene (StDvB) based poly(HIPEs) showed hydrophobicity and fuel sorption capacities as high as 4.8 (g/g). Pore hierarchy, namely pore openness, regulated sorption capacity, and sorption times where greater openness resulted in faster sorption and increased sorption capacity. Monoliths were subject to 20 sorption-desorption cycles demonstrating recyclability and stable sorption capacity. Finally, CNX/surfactant hybrids made it possible to reduce surfactant requirements for successful HIPE formation and stabilization during polymerization. All poly(HIPEs) retained acceptable conversion as a function of CNX loading nearing 90% or better with thermal stability as high as 283 °C.
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31
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Fontenot CL, Pojman JA. Self and Conspecific Dermatophagy in the Aquatic Salamander Amphiuma tridactylum. SOUTHEAST NAT 2016. [DOI: 10.1656/058.015.0312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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32
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Holt T, Fazende K, Jee E, Wu Q, Pojman JA. Cure‐on‐demand wood adhesive based on the frontal polymerization of acrylates. J Appl Polym Sci 2016. [DOI: 10.1002/app.44064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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33
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Abedin R, Pojman JA, Knopf FC, Rice RG. Suspended Droplet Polymerization in an Unstable, Vibrating Shallow-Bed Reactor. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.5b04216] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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34
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Jee E, Bánsági T, Taylor AF, Pojman JA. Temporal Control of Gelation and Polymerization Fronts Driven by an Autocatalytic Enzyme Reaction. Angew Chem Int Ed Engl 2016; 55:2127-31. [PMID: 26732469 PMCID: PMC4755207 DOI: 10.1002/anie.201510604] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 12/15/2022]
Abstract
Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation that exploits an inbuilt switch: the increase in pH after an induction period in the urease-catalyzed hydrolysis of urea was used to trigger the base-catalyzed Michael addition of a water-soluble trithiol to a polyethylene glycol diacrylate. The time to gelation (minutes to hours) was either preset through the initial concentrations or the reaction was initiated locally by a base, thus resulting in polymerization fronts that converted the mixture from a liquid into a gel (ca. 0.1 mm min(-1)). The rate of hydrolytic degradation of the hydrogel depended on the initial concentrations, thus resulting in a gel lifetime of hours to months. In this way, temporal programming of gelation was possible under mild conditions by using the output of an autocatalytic enzyme reaction to drive both the polymerization and subsequent degradation of a hydrogel.
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Jee E, Bánsági T, Taylor AF, Pojman JA. Temporal Control of Gelation and Polymerization Fronts Driven by an Autocatalytic Enzyme Reaction. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 128:2167-2171. [PMID: 27478280 PMCID: PMC4950125 DOI: 10.1002/ange.201510604] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 01/19/2023]
Abstract
Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation that exploits an inbuilt switch: the increase in pH after an induction period in the urease-catalyzed hydrolysis of urea was used to trigger the base-catalyzed Michael addition of a water-soluble trithiol to a polyethylene glycol diacrylate. The time to gelation (minutes to hours) was either preset through the initial concentrations or the reaction was initiated locally by a base, thus resulting in polymerization fronts that converted the mixture from a liquid into a gel (ca. 0.1 mm min-1). The rate of hydrolytic degradation of the hydrogel depended on the initial concentrations, thus resulting in a gel lifetime of hours to months. In this way, temporal programming of gelation was possible under mild conditions by using the output of an autocatalytic enzyme reaction to drive both the polymerization and subsequent degradation of a hydrogel.
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36
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Hong S, Lian H, Sun X, Pan D, Carranza A, Pojman JA, Mota-Morales JD. Zinc-based deep eutectic solvent-mediated hydroxylation and demethoxylation of lignin for the production of wood adhesive. RSC Adv 2016. [DOI: 10.1039/c6ra18290a] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Choline chloride–ZnCl2 deep-eutectic solvent (ChCl–ZnCl2 DES), mole ratio 1 : 2, was used to improve the chemical reactivity of wheat straw alkali lignin under different temperatures and times of pretreatment.
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Zhang W, Tullier MP, Patel K, Carranza A, Pojman JA, Radadia AD. Microfluidics using a thiol-acrylate resin for fluorescence-based pathogen detection assays. LAB ON A CHIP 2015; 15:4227-4231. [PMID: 26371689 DOI: 10.1039/c5lc00971e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate thiol-acrylate microfluidics prepared via soft lithography for single-step protein immobilization and fluorescence-based pathogen detection. Such microfluidics are formed via room temperature curing, and bonded without oxygen plasma. The background fluorescence of the resin was found to be similar to PDMS for several filter sets. We also show that thiol-acrylate devices are able to bond to gold-coated surfaces, which allows for integration with microfabricated sensors.
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38
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Totaro NP, Murphy ZD, Burcham AE, King CT, Scherr TF, Bounds CO, Dasa V, Pojman JA, Hayes DJ. In vitro evaluation of thermal frontally polymerized thiol-ene composites as bone augments. J Biomed Mater Res B Appl Biomater 2015; 104:1152-60. [PMID: 26061219 DOI: 10.1002/jbm.b.33466] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 03/31/2015] [Accepted: 05/07/2015] [Indexed: 11/12/2022]
Abstract
Because of the large number of total knee replacement (TKR) surgeries conducted per year, and with projections of increased demand to almost a million primary TKR surgeries per year by 2030 in the United States alone, there is a need to discover more efficient working materials as alternatives to current bone cements. There is a need for surgeons and hospitals to become more efficient and better control over the operative environment. One area of inefficiency is the cement steps during TKR. Currently the surgeon has very little control over cement polymerization. This leads to an increase in time, waste, and procedural inefficiencies. There is a clear need to create an extended working time, moldable, osteoconductive, and osteoinductive bone augment as a substitution for the current clinically used bone cement where the surgeon has better control over the polymerization process. This study explored several compositions of pentaerythritol-co-trimethylolpropane tris-(3-mercaptopropionate) hydroxyapatite composite materials prepared via benzoyl peroxide-initiated thermal frontal polymerization. The 4:1 acrylate to thiol ratio containing augment material shows promise with a maximal propagation temperature of 160°C ± 10°C, with mechanical strength of 3.65 MPa, and 111% cytocompatibility, relative to the positive control. This frontally polymerized material may have application as an augment with controlled polymerization supporting cemented implants. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1152-1160, 2016.
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Kiss IZ, Pojman JA. Introduction to Focus Issue: Oscillations and Dynamic Instabilities in Chemical Systems: Dedicated to Irving R. Epstein on occasion of his 70th birthday. CHAOS (WOODBURY, N.Y.) 2015; 25:064201. [PMID: 26117111 DOI: 10.1063/1.4922594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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40
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McFarland B, Pojman JA. Effects of shell crosslinking on polyurea microcapsules containing a free-radical initiator. J Appl Polym Sci 2015. [DOI: 10.1002/app.42408] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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41
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Nuvoli D, Alzari V, Pojman JA, Sanna V, Ruiu A, Sanna D, Malucelli G, Mariani A. Synthesis and characterization of functionally gradient materials obtained by frontal polymerization. ACS APPLIED MATERIALS & INTERFACES 2015; 7:3600-3606. [PMID: 25611548 DOI: 10.1021/am507725k] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Functionally gradient materials (FGMs) with gradual and continuous changes of their properties in one or more dimensions are useful in a wide range of applications. However, obtaining such materials with accurate control of the gradient, especially when the gradient is nonlinear, is not easy. In this work, frontal polymerization (FP) was exploited to synthesize polymeric FGMs. We demonstrated that the use of ascending FP with continuous feeding of monomers with computer-controlled peristaltic pumps provided an excellent method for the preparation of functionally gradient materials with programmed gradients. To test the effectiveness of the method, copolymers made from triethylene glycol dimethacrylate/hexyl methacrylate with linear and hyperbolic gradient in composition were synthesized. Differential scanning calorimetry (DSC), Shore A hardness measurements, compression tests, and swelling studies were performed along the length of the materials to assess the relationship between the gradients and the material properties. Glass transition temperatures, determined by DSC, showed a linear dependence on the composition and were in agreement with theoretical values. The other properties showed different and specific behaviors as a function of the compositional gradient.
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Chen C, Garber L, Smoak M, Fargason C, Scherr T, Blackburn C, Bacchus S, Lopez MJ, Pojman JA, Del Piero F, Hayes DJ. In vitro and in vivo characterization of pentaerythritol triacrylate-co-trimethylolpropane nanocomposite scaffolds as potential bone augments and grafts. Tissue Eng Part A 2014; 21:320-31. [PMID: 25134965 DOI: 10.1089/ten.tea.2014.0018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A thiol-acrylate-based copolymer synthesized via an amine-catalyzed Michael addition was studied in vitro and in vivo to assess its potential as an in situ polymerizing graft or augment in bone defect repair. The blends of hydroxyapatite (HA) with pentaerythritol triacrylate-co-trimethylolpropane (PETA), cast as solids or gas foamed as porous scaffolds, were evaluated in an effort to create a biodegradable osteogenic material for use as a bone-void-filling augment. Osteogenesis experiments were conducted with human adipose-derived mesenchymal stromal cells (hASCs) to determine the ability of the material to serve as an osteoinductive substrate. Poly(ɛ-caprolactone) (PCL) composites PCL:HA (80:20) (wt/wt%) served as the control scaffold, while the experimental scaffolds included PETA:HA (100:0), (85:15), (80:20), and (75:25) composites (wt/wt%). The results indicate that PETA:HA (80:20) foam composites had higher mechanical strength than the corresponding porous PCL:HA (80:20) scaffolds made by thermo-precipitation method, and in the case of foamed composites, increasing HA content directly correlated with increased yield strength. For cytotoxicity and osteogenesis experiments, hASCs cultured for 21 days on PETA:HA scaffolds in stromal medium displayed the greatest number of live cells compared with PCL:HA composites. Moreover, hASCs cultured on foamed PETA:HA (80:20) scaffolds resulted in the greatest mineralization, increased alkaline phosphatase (ALP) expression, and the highest osteocalcin (OCN) expression after 21 days. Overall, the PETA:HA (80:20) and PETA:HA (85:15) scaffolds, with 66.38% and 72.02% porosity, respectively, had higher mechanical strength and cytocompatibility compared with the PCL:HA control. The results of the 6-week in vivo biocompatibility study using a posterior lumbar spinal fusion model demonstrate that PETA:HA can be foamed in vivo without serious adverse effects at the surgical site. Additionally, it was demonstrated that cells migrate into the interconnected pore volume and are found within centers of ossification.
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Smoak M, Chen C, Qureshi A, Garber L, Pojman JA, Janes ME, Hayes DJ. Antimicrobial cytocompatible pentaerythritol triacrylate-co-trimethylolpropane composite scaffolds for orthopaedic implants. J Appl Polym Sci 2014. [DOI: 10.1002/app.41099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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44
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Carranza A, Gewin M, Pojman JA. Europium-doped aluminum oxide phosphors as indicators for frontal polymerization dynamics. CHAOS (WOODBURY, N.Y.) 2014; 24:023118. [PMID: 24985432 DOI: 10.1063/1.4876438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this study, we present an inexpensive and practical method that allows the monitoring and visualization of front polymerization, propagation, and dynamics. Commercially available europium-doped aluminum oxide powders were combined with video imaging to visualize free-radical propagating polymer fronts. In order to demonstrate the applicability of this method, frontal copolymerization reactions of propoxylated glycerin triacrylate (EB53), pentaerythritol triacrylate (PETA), and pentaerythritol tetra-acrylate (PETEA) with 1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane (Luperox 231®) as an initiator were studied and compared to the results obtained by IR imaging. Systems exhibiting higher filler loading, higher EB53 content, and less acrylated monomers showed a marked decrease in front velocity, while those with more acrylated monomers and higher crosslinking density showed a marked increase in front velocity. Finally, in order to show the potential of the imaging technique, we studied fronts propagating in planar and spherical geometries.
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Scognamillo S, Bounds C, Thakuri S, Mariani A, Wu Q, Pojman JA. Frontal cationic curing of epoxy resins in the presence of defoaming or expanding compounds. J Appl Polym Sci 2014. [DOI: 10.1002/app.40339] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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46
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Higham AK, Garber LA, Latshaw DC, Hall CK, Pojman JA, Khan SA. Gelation and Cross-Linking in Multifunctional Thiol and Multifunctional Acrylate Systems Involving an in Situ Comonomer Catalyst. Macromolecules 2014. [DOI: 10.1021/ma402157f] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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47
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Garber L, Chen C, Kilchrist KV, Bounds C, Pojman JA, Hayes D. Thiol-acrylate nanocomposite foams for critical size bone defect repair: A novel biomaterial. J Biomed Mater Res A 2013; 101:3531-41. [DOI: 10.1002/jbm.a.34651] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 02/04/2013] [Accepted: 02/05/2013] [Indexed: 12/13/2022]
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48
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Bounds CO, Upadhyay J, Totaro N, Thakuri S, Garber L, Vincent M, Huang Z, Hupert M, Pojman JA. Fabrication and characterization of stable hydrophilic microfluidic devices prepared via the in situ tertiary-amine catalyzed Michael addition of multifunctional thiols to multifunctional acrylates. ACS APPLIED MATERIALS & INTERFACES 2013; 5:1643-1655. [PMID: 23406255 DOI: 10.1021/am302544h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In situ tertiary amine-catalyzed thiol-acrylate chemistry was employed to produce hydrophilic microfluidic devices via a soft lithography process. The process involved the Michael addition of a secondary amine to a multifunctional acrylate producing a nonvolatile in situ tertiary amine catalyst/comonomer molecule. The Michael addition of a multifunctional thiol to a multifunctional acrylate was facilitated by the catalytic activity of the in situ catalyst/comonomer. These cost-efficient thiol-acrylate devices were prepared at room temperature, rapidly, and with little equipment. The thiol-acrylate thermoset materials were more natively hydrophilic than the normally employed poly(dimethylsiloxane) (PDMS) thermoset material, and the surface energies were stable compared to PDMS. Because the final chip was self-adhered via a simple chemical process utilizing the same chemistry, and it was naturally hydrophilic, there was no need for expensive instrumentation or complicated methods to "activate" the surface. There was also no need for postprocessing removal of the catalyst as it was incorporated into the polymer network. These bottom-up devices were fabricated to completion proving their validity as microfluidic devices, and the materials were manipulated and characterized via various analyses illustrating the potential diversity and tunability of the devices.
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Mota-Morales JD, Gutiérrez MC, Ferrer ML, Sanchez IC, Elizalde-Peña EA, Pojman JA, Monte FD, Luna-Bárcenas G. Deep eutectic solvents as both active fillers and monomers for frontal polymerization. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/pola.26555] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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50
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Wrobel MM, Bánsági T, Scott SK, Taylor AF, Bounds CO, Carranza A, Pojman JA. pH wave-front propagation in the urea-urease reaction. Biophys J 2013; 103:610-615. [PMID: 22947878 DOI: 10.1016/j.bpj.2012.06.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/06/2012] [Accepted: 06/14/2012] [Indexed: 11/27/2022] Open
Abstract
The urease-catalyzed hydrolysis of urea displays feedback that results in a switch from acid (pH ~3) to base (pH ~9) after a controllable period of time (from 10 to >5000 s). Here we show that the spatially distributed reaction can support pH wave fronts propagating with a speed of the order of 0.1-1 mm min(-1). The experimental results were reproduced qualitatively in reaction-diffusion simulations including a Michaelis-Menten expression for the urease reaction with a bell-shaped rate-pH dependence. However, this model fails to predict that at lower enzyme concentrations, the unstirred reaction does not always support fronts when the well-stirred reaction still rapidly switches to high pH.
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