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David P. Cole Ezat Khosravi Osama M. Musa 《Journal of polymer science. Part A, Polymer chemistry》2016,54(3):335-344
We describe here the first example of the synthesis of 4‐arm star poly(acrylic acid) for use as a water‐soluble drag reducing agent, by applying Cu(0)‐mediated polymerization technique. High molecular weight 4‐arm star poly(tert‐butyl acrylate) (Mn = 3.0–9.0 × 105 g mol?1) was first synthesized using 4,4′‐oxybis(3,3‐bis(2‐bromopropionate)butane as an initiator and a simple Cu(0)/TREN catalyst system. Then, 4‐arm star poly(tert‐butyl acrylate) were subjected to hydrolysis using trifluoroacetic acid resulting in water‐soluble 4‐arm star poly(acrylic acid). Drag reduction test rig analysis showed 4‐arm star poly(acrylic acid) to be effective as a drag reducing agent with drag reduction of 24.3%. Moreover, 4‐arm star poly(acrylic acid) exhibited superior mechanical stability when compared with a linear poly(acrylic acid) and commercially available drag reducing polymers; Praestol and poly(ethylene oxide). The linear poly(acrylic acid), Praestol, and poly(ethylene oxide) all showed a large decrease in drag reduction of 8–12% when cycled 30 times through the drag reduction test rig while, in contrast, 4‐arm star poly(acrylic acid) demonstrated much higher mechanical stability. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 335–344 相似文献
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İsmaıl Nacı Cangül Musa Demırcı İlker İnam Florian Luca Gökhan Soydan 《Mathematica Slovaca》2013,63(3):647-659
In this note, we find all the solutions of the Diophantine equation x 2 + 2 a · 3 b · 11 c = y n , in nonnegative integers a, b, c, x, y, n ≥ 3 with x and y coprime. 相似文献
66.
The development of an optical biosensor based on immobilization of 3-methyl-2-benzothiazolinone hydrazone (MBTH) in hybrid nafion/sol-gel silicate film and tyrosinase in chitosan film for the detection of phenolic compounds has been described. Tyrosinase was immobilized in chitosan film deposited on the hybrid nafion/sol-gel silicate film containing MBTH. The enzymatic oxidation product of phenolic compounds were stabilized through formation of adduct with MBTH to produce a maroon color adduct. The color intensity of adduct was found to increase proportionally with the increase of the substrate concentrations after 5 min exposure. The linearity of the biosensor towards phenol, catechol and m-cresol were in the respective concentration range of 0.5-7.0, 0.5-10.0 and 1.0-13.0 mg/L with detection limit of 0.18, 0.23 and 0.43 mg/L, respectively. The biosensor shows a good stability for at least 3 months. 相似文献
67.
Synthesis characterization and biological study of diorganotin(IV) complexes of monomethyl phthalate
Rehman W Baloch MK Badshah A Ali S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,65(3-4):689-694
The synthesis and characterization of new coordination compounds of some organotin(IV) chlorides with monomethyl phthalate is reported; the ligand molecules appear to be bound to the tin atom through carbonyl oxygen atoms. Their structures have been characterized by elemental analyses, molar conductance, and bonding in these complexes is discussed in terms of their IR, (1)H, (13)C, (119)Sn NMR and (119 m)Sn M?ssbauer spectral studies. The spectroscopic results obtained are in full agreement with the proposed 2:1 stoichiometry. The complexes soluble in DMSO have been screened against a wide spectrum of bacteria and the results obtained are quite promising. The LD(50) values have also been determined in the albino rats. Some of the complexes also exhibit high anti-inflammatory activity. 相似文献
68.
Molecularly imprinted polymer (MIP) may not selectively recognize small template of limited number of functional groups, such as 2-chlorophenol (2-CP). In this work, a novel method was proposed to improve the recognition ability of the molecularly imprinted solid phase extraction (MISPE) of 2-CP from environmental waters. This was achieved by derivatization of 2-CP with 4-amino-anti-pyrine (4-AAP) to enlarge its molecular size and add more binding sites. For that purpose, two MISPE methods of 2-CP were developed. In method 1, a polymer imprinted with 2-CP was used as the extracting sorbent but it suffered from low selectivity and high detection limit of 2-CP (7.10 ng L−1). In method 2, a polymer imprinted with 4-AAP derivatized 2-CP (2-CP-4-AAP) was used as the extracting sorbent. Prior to loading the water sample it was subjected to a simple derivatization procedure with 4-AAP. Method 2 showed high recognition ability/selectivity towards 2-CP-4-AAP with lower detection limit of 0.05 ng L−1 for 2-CP-4-AAP. Method 2 was able to detect the presence of 2-CP-4-AAP in unspiked real water samples and almost full spike recovery was achieved. 相似文献
69.
Musa Kaeem Baloch 《Journal of Macromolecular Science: Physics》2013,52(2-3):151-180
Scaling in terms of temperature, composition, and molecular weight variables has practical and fundamental significance. The viscosity of polymer solutions deviates from that predicted by the Huggins equation when the concentration is higher than a characteristic concentration cch. The value of cch depends on the molecular weight of the polymer and the thermodynamic conditions of the system. It is also a known fact that the deviations are due to the entanglements and interactions of polymer molecules. Therefore, we believe cch can be used as a concentration-reducing parameter to get the superposition curves. It can be shown that the concentration corresponding to a minimum value of ηsp/ch2 (in the case of ηsp/c2 vs concentration curves) is the value of cch of that system. Moreover, this cch is related to the intrinsic viscosity and molecular weight through the Huggins and Mark-Hauwink-Sakurada equations (cch = k′M?a′). Using cch values for different systems and plotting log ηr versus C/Cch, the superposition curves are obtained. In each case these curves are found to be linear, at least when concentrations approach zero. Master curves may be plotted by making use of the initial slopes of the curve (log ηr vs Bc/cch) and it is found that the data obtained at different thermodynamic conditions fit these (log ηr vs Bc/cch, B being the initial slope of log η vs c/cch) curves very well. The slopes are also compared to k′, a′, and the expansion coefficient of the system and the relationships are found to be linear. It is concluded that cch is a better parameter for the superposition of viscosity data, as well as being easy to obtain experimentally. 相似文献
70.
Zahra JA el-Abadelah MM Nazer MZ Ebraheem KA Boese R 《Organic & biomolecular chemistry》2003,1(10):1798-1801
The tautomerism of 4-methyldihydro-1,3,4-benzotriazepin-5-ones (2,3) is re-investigated by means of X-ray diffraction and quantum chemical calculations. The data revealed that the model compound (2a) exists in the amidrazone 1,4-dihydro tautomeric form (A), but not in the alternate 3,4-dihydro tautomer (B) as was previously reported. 相似文献