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Malcolm A Kelland - One of the best experts on this subject based on the ideXlab platform.
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n n dimethylhydrazidoacrylamides part 3 improving kinetic hydrate inhibitor performance using polymers of n n dimethylhydrazidomethacrylamide
Energy & Fuels, 2015Co-Authors: Mohamed F Mady, Malcolm A KellandAbstract:A series of Homopolymers of N,N-dimethylhydrazidomethacrylamide (DMHMAM) and copolymers with (N-isopropylmethacrylamide) (IPMAM) have been synthesized and investigated as kinetic hydrate inhibitors (KHIs) with a structure-II-forming synthetic hydrocarbon gas mixture in high-pressure steel rocking cells. The same polymerization method to give similar low molecular weights was used to aid KHI performance comparison. The homopolymer polyDMHMAM was found to give good KHI performance, significantly better than the related homopolymer, poly(N,N-dimethylhydrazidoacrylamide) (polyDMHAM), which does not have methyl groups in the backbone. This is in agreement with previous studies on N-alkylmethacrylamides. PolyDMHMAM also has no cloud point in deionized water up to 95+ °C, making it suitable for injection in high-temperature wells. A 1:1 N,N-dimethylhydrazidomethacrylamide/N-isopropylmethacrylamide copolymer (1:1 DMHMAM/IPMAM copolymer; Mn = 2100) also exhibited no cloud point in deionized water and showed an imp...
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Non-Amide Kinetic Hydrate Inhibitors: Performance of a Series of Polymers of Isopropenyloxazoline on Structure II Gas Hydrates
2015Co-Authors: Fernando T. Reyes, Edward L. Malins, Remzi C. Becer, Malcolm A KellandAbstract:A series of polymers containing the 2-isopropenyl-2-oxazoline (iPOx) monomer have been synthesized by either anionic polymerization or RAFT polymerization. Both Homopolymers of varying molecular weight were prepared as well as copolymers with methyl methacrylate (MMA) and N-isopropylmethacrylamide (NIPMAM) comonomers. The iPOx Homopolymers were shown to be very poor Structure II tetrahydrofuran hydrate crystal growth inhibitors, indicating weak interaction of the oxazoline group with the hydrate crystal surface. They were also tested for their performance as kinetic hydrate inhibitors on a Structure-II-forming natural gas mixture. The Homopolymers showed significant and increasing performance as the molecular weight decreased to 2000 Da. Copolymerization of iPOx with MMA did not improve the KHI performance, but copolymers of iPOx with NIPMAM did show an improvement, although not as good performance as polyNIPMAM homopolymer of similar molecular weight. However, using a 35:20 molar ratio iPOx:NIPMAM copolymer it is possible to obtain good KHI performance and a high cloud point of 70 °C in water, which is useful for injection into hot fluids. These results demonstrate that polymers containing predominantly non-amide-based monomers such as iPOx can be useful, high cloud point KHIs. In the case of iPOx polymers the primary inhibition mechanism appears to be nucleation inhibition since hydrate crystal growth inhibition is poor
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Non-Amide Kinetic Hydrate Inhibitors: Performance of a Series of Polymers of Isopropenyloxazoline on Structure II Gas Hydrates
Energy & Fuels, 2013Co-Authors: Fernando T. Reyes, Edward L. Malins, C. Remzi Becer, Malcolm A KellandAbstract:A series of polymers containing the 2-isopropenyl-2-oxazoline (iPOx) monomer have been synthesized by either anionic polymerization or RAFT polymerization. Both Homopolymers of varying molecular weight were prepared as well as copolymers with methyl methacrylate (MMA) and N-isopropylmethacrylamide (NIPMAM) comonomers. The iPOx Homopolymers were shown to be very poor Structure II tetrahydrofuran hydrate crystal growth inhibitors, indicating weak interaction of the oxazoline group with the hydrate crystal surface. They were also tested for their performance as kinetic hydrate inhibitors on a Structure-II-forming natural gas mixture. The Homopolymers showed significant and increasing performance as the molecular weight decreased to 2000 Da. Copolymerization of iPOx with MMA did not improve the KHI performance, but copolymers of iPOx with NIPMAM did show an improvement, although not as good performance as polyNIPMAM homopolymer of similar molecular weight. However, using a 35:20 molar ratio iPOx:NIPMAM copolymer it is possible to obtain good KHI performance and a high cloud point of 70 °C in water, which is useful for injection into hot fluids. These results demonstrate that polymers containing predominantly non-amide-based monomers such as iPOx can be useful, high cloud point KHIs. In the case of iPOx polymers the primary inhibition mechanism appears to be nucleation inhibition since hydrate crystal growth inhibition is poor.
Bradley D. Olsen - One of the best experts on this subject based on the ideXlab platform.
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self diffusion and constraint release in isotropic entangled rod coil block copolymers
Macromolecules, 2015Co-Authors: Muzhou Wang, Ksenia Timachova, Bradley D. OlsenAbstract:Understanding dynamic relaxation mechanisms in self-diffusion and constraint release processes of rod–coil block copolymers is important for many technological applications that employ neat melts or concentrated solutions. Using a model system composed of poly(alkoxyphenylenevinylene) rods and polyisoprene coils, reptation theories of entangled rod–coil block copolymers are investigated in the isotropic melt state. Self-diffusion was measured by forced Rayleigh scattering using a red laser line and a new blue photoswitchable dye that allow operation above the bandgap of most semiconducting polymers. In contrast to previous tracer studies where the diffusion of rod–coils through a coil homopolymer matrix is slowed relative to coil Homopolymers because of a mismatch in the curvature of the rod and coil entanglement tubes, slowed diffusion is only present in self-diffusion measurements above a critical molecular weight. An activated reptation mechanism with constraint release is proposed as a modification to...
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experimental measurement of coil rod coil block copolymer tracer diffusion through entangled coil Homopolymers
Macromolecules, 2013Co-Authors: Muzhou Wang, Ksenia Timachova, Bradley D. OlsenAbstract:The diffusion of coil–rod–coil triblock copolymers in entangled coil Homopolymers is experimentally measured and demonstrated to be significantly slower than rod or coil Homopolymers of the same molecular weight. A model coil–rod–coil triblock was prepared by expressing rodlike alanine-rich α-helical polypeptides in E. coli and conjugating coil-like poly(ethylene oxide) (PEO) to both ends to form coil–rod–coil triblock copolymers. Tracer diffusion through entangled PEO homopolymer solutions was measured using forced Rayleigh scattering at various rod lengths and coil molecular weights for the tracer, and various concentrations for the coil homopolymer solutions. For rod lengths, L, that are close to the entanglementh length, a, the ratio between the diffusivity of a triblock and the diffusivity of a coil homopolymer of the same molecular weight decreases monotonically and is only a function of L/a, in quantitative agreement with previous simulation results. For large rod lengths, diffusion follows an arm ...
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universalization of the phase diagram for a model rod coil diblock copolymer
Macromolecules, 2008Co-Authors: Bradley D. Olsen, Manas Shah, Venkat Ganesan, Rachel A SegalmanAbstract:The Flory−Huggins interaction is measured for a model rod−coil block copolymer system, poly(alkoxyphenylenevinylene-b-isoprene), by fitting the interfacial segregation of block copolymer to a homopolymer interface and by using the random phase approximation (RPA) for block copolymers. The measured interfacial segregation of a block copolymer to the interface between Homopolymers, fit with a self-consistent field theory (SCFT) simulation using χ as a variable parameter, gives a functional form χ = 34.8/T − 0.091. When RPA is applied to neutron scattering curves for the rod−coil system above the order−disorder transition, the theoretical structure factors are inconsistent with observed scattering curves due to complex aggregated structures formed in the nematic and isotropic states. Using the Flory−Huggins parameter and a previously measured value of the Maier−Saupe parameter, the PPV-b-PI phase diagram may be converted from system-specific variables to dimensionless parameters. Under the assumptions that t...
Xiaozheng Duan - One of the best experts on this subject based on the ideXlab platform.
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effects of repulsion parameter and chain length of Homopolymers on interfacial properties of an ax 2bxax 2 bm blends a dpd simulation study
Polymers, 2021Co-Authors: Dongmei Liu, Kai Gong, Ye Lin, Tao Liu, Xiaozheng DuanAbstract:We explored the effects of the repulsion parameter (aAB) and chain length (NHA or NHB) of Homopolymers on the interfacial properties of An/Ax/2BxAx/2/Bm ternary polymeric blends using dissipative particle dynamics (DPD) simulations. Our simulations show that: (i) The ternary blends exhibit the significant segregation at the repulsion parameter (aAB = 40). (ii) Both the interfacial tension and the density of triblock copolymer at the center of the interface increase to a plateau with increasing the homopolymer chain length, which indicates that the triblock copolymers with shorter chain length exhibit better performance as the compatibilizers for stabilizing the blends. (iii) For the case of NHA = 4 (chain length of Homopolymers An) and NHB (chain length of Homopolymers Bm) ranging from 16 to 64, the blends exhibit larger interfacial widths with a weakened correlation between bead An and Bm of Homopolymers, which indicates that the triblock copolymer compatibilizers (Ax/2BxAx/2) show better performance in reducing the interfacial tension. The effectiveness of triblock copolymer compatibilizers is, thus, controlled by the regulation of repulsion parameters and the homopolymer chain length. This work raises important considerations concerning the use of the triblock copolymer as compatibilizers in the immiscible homopolymer blend systems.
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Effects of Repulsion Parameter and Chain Length of Homopolymers on Interfacial Properties of An/Ax/2BxAx/2/Bm Blends: A DPD Simulation Study
'MDPI AG', 2021Co-Authors: Dongmei Liu, Kai Gong, Ye Lin, Tao Liu, Xiaozheng DuanAbstract:We explored the effects of the repulsion parameter (aAB) and chain length (NHA or NHB) of Homopolymers on the interfacial properties of An/Ax/2BxAx/2/Bm ternary polymeric blends using dissipative particle dynamics (DPD) simulations. Our simulations show that: (i) The ternary blends exhibit the significant segregation at the repulsion parameter (aAB = 40). (ii) Both the interfacial tension and the density of triblock copolymer at the center of the interface increase to a plateau with increasing the homopolymer chain length, which indicates that the triblock copolymers with shorter chain length exhibit better performance as the compatibilizers for stabilizing the blends. (iii) For the case of NHA = 4 (chain length of Homopolymers An) and NHB (chain length of Homopolymers Bm) ranging from 16 to 64, the blends exhibit larger interfacial widths with a weakened correlation between bead An and Bm of Homopolymers, which indicates that the triblock copolymer compatibilizers (Ax/2BxAx/2) show better performance in reducing the interfacial tension. The effectiveness of triblock copolymer compatibilizers is, thus, controlled by the regulation of repulsion parameters and the homopolymer chain length. This work raises important considerations concerning the use of the triblock copolymer as compatibilizers in the immiscible homopolymer blend systems
Dongmei Liu - One of the best experts on this subject based on the ideXlab platform.
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effects of repulsion parameter and chain length of Homopolymers on interfacial properties of an ax 2bxax 2 bm blends a dpd simulation study
Polymers, 2021Co-Authors: Dongmei Liu, Kai Gong, Ye Lin, Tao Liu, Xiaozheng DuanAbstract:We explored the effects of the repulsion parameter (aAB) and chain length (NHA or NHB) of Homopolymers on the interfacial properties of An/Ax/2BxAx/2/Bm ternary polymeric blends using dissipative particle dynamics (DPD) simulations. Our simulations show that: (i) The ternary blends exhibit the significant segregation at the repulsion parameter (aAB = 40). (ii) Both the interfacial tension and the density of triblock copolymer at the center of the interface increase to a plateau with increasing the homopolymer chain length, which indicates that the triblock copolymers with shorter chain length exhibit better performance as the compatibilizers for stabilizing the blends. (iii) For the case of NHA = 4 (chain length of Homopolymers An) and NHB (chain length of Homopolymers Bm) ranging from 16 to 64, the blends exhibit larger interfacial widths with a weakened correlation between bead An and Bm of Homopolymers, which indicates that the triblock copolymer compatibilizers (Ax/2BxAx/2) show better performance in reducing the interfacial tension. The effectiveness of triblock copolymer compatibilizers is, thus, controlled by the regulation of repulsion parameters and the homopolymer chain length. This work raises important considerations concerning the use of the triblock copolymer as compatibilizers in the immiscible homopolymer blend systems.
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Effects of Repulsion Parameter and Chain Length of Homopolymers on Interfacial Properties of An/Ax/2BxAx/2/Bm Blends: A DPD Simulation Study
'MDPI AG', 2021Co-Authors: Dongmei Liu, Kai Gong, Ye Lin, Tao Liu, Xiaozheng DuanAbstract:We explored the effects of the repulsion parameter (aAB) and chain length (NHA or NHB) of Homopolymers on the interfacial properties of An/Ax/2BxAx/2/Bm ternary polymeric blends using dissipative particle dynamics (DPD) simulations. Our simulations show that: (i) The ternary blends exhibit the significant segregation at the repulsion parameter (aAB = 40). (ii) Both the interfacial tension and the density of triblock copolymer at the center of the interface increase to a plateau with increasing the homopolymer chain length, which indicates that the triblock copolymers with shorter chain length exhibit better performance as the compatibilizers for stabilizing the blends. (iii) For the case of NHA = 4 (chain length of Homopolymers An) and NHB (chain length of Homopolymers Bm) ranging from 16 to 64, the blends exhibit larger interfacial widths with a weakened correlation between bead An and Bm of Homopolymers, which indicates that the triblock copolymer compatibilizers (Ax/2BxAx/2) show better performance in reducing the interfacial tension. The effectiveness of triblock copolymer compatibilizers is, thus, controlled by the regulation of repulsion parameters and the homopolymer chain length. This work raises important considerations concerning the use of the triblock copolymer as compatibilizers in the immiscible homopolymer blend systems
Alina V Maryasevskaya - One of the best experts on this subject based on the ideXlab platform.
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synthesis and solid state properties of polyc3 co polymers containing ch2 ch2 c coor 2 repeat units with densely packed fluorocarbon lateral chains
Macromolecules, 2019Co-Authors: Nicolas Illy, Deogratias Urayeneza, Alina V Maryasevskaya, Laurent Michely, Sylvie Boileau, Blandine Brissault, Egor A Bersenev, Denis V AnokhinAbstract:The synthesis and structural characterization of linear PolyC3 polymers containing trimethylene-1,1-dicarboxylate structural repeat units with C6F13 and C8F17 fluorinated side chains is described for the first time, and their properties were compared with the traditional polyvinyl structures that display the fluorinated chain on every second rather than on every third carbon alongside the backbone. Homopolymers as well as statistical and block copolymers with n-propyl and/or allyl trimethylene-1,1-dicarboxylate blocks have been obtained from PolyC3 precursors containing diallyl trimethylene-1,1-dicarboxylate units, by reacting C6F13−C2H4−SH and C8F17−C2H4−SH thiols with the allyl groups using a thiol−ene post- polymerization modification reaction. Solid-state properties have been investigated by differential scanning calorimetry for all of the (co)polymers and by small-angle X-ray scattering/wide-angle X-ray scattering for the C8F17 homopolymer at several temperatures. The structure of the homopolymer consistently shows a coexistence of two smectic phases at room temperature, which can be identified as SmB and SmC. This coexistence is assumed to arise from the fact that the distances between carboxylic oxygens bonded to the same carbon are very close to the ones between the neighboring carboxylic oxygens alongside the backbone, resulting in two possible ways of packing the pendant fluoroalkyl chains arranged in a hexatic order.