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Otilia Catanescu Nicolae Hurduc Dan Scutaru Aurel Stoleru Cristofor I. Simionescu 《大分子材料与工程》1999,273(1):91-95
Polyethers based on bis(2-chloroethyl) ether and various bisphenols were obtained using a phase transfer catalysis technique in a liquid/liquid system. 4,4′-Dihydroxyazobenzene, 4,4′-dihydroxybiphenyl, bisphenol A, 2,7-dihydroxynaphthalene and 4,4′-dihydroxydiphenyl) sulfide were used. Only the polymers with azobenzene and biphenyl units exhibited mesophases, since the others have semi-crystalline or amorphous structures. The polymers were characterized by 1H NMR, DSC and optical microscopy in polarized light. The molecular weights of the samples were low, situated in the oligomeric domain. The various transfer rates of the bisphenols from the aqueous to the organic phase, in some cases, led to very different copolymerization ratios as compared to the feed ratios. The LC polymers exhibited monotropic mesophases, probably for conformational reasons. A comparison between similar polyether structures containing the diethyletheric spacer and an oxetanic one was effectuated. 相似文献
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Ioana Moleavin Silvia Grama Irina Cârlescu Dan Scutaru Nicolae Hurduc 《Polymer Bulletin》2010,65(1):69-81
Photosensitive micelles based on amphiphilic azo-polysiloxanes were obtained and characterized. The amphiphilic polymers were
synthesized in a two-step reaction, starting from a polysiloxane containing chlorobenzyl groups in the side chain. In the
first step, the polysiloxane was modified with azo-aromatic groups (35–45% substitution degree) and in the second step the
unreacted chlorobenzyl groups were quaternized, using different tertiary amines. The structure of the polysiloxanes and their
aggregation/disaggregation capacity were evaluated by 1H-NMR, DSC, fluorescence and UV–VIS spectroscopy, dynamic light scattering
and transmission electron microscopy. All the amphiphilic polysiloxanes are capable of generating micelles, the critical concentration
of the aggregation values being situated in the range 10−3–10−2 g/L. As a function of the ternary amine structure used in the quarterisation reaction, the micellar aggregation process is
different, individual micelles or micellar clusters being obtained. The clusters' dimension cannot be controlled, the polydispersity
index having high values. The disaggregation processes of the micelles under UV irradiation reveal that the polymer chemical
structure influences the aggregates stability. A total micelles disaggregation was obtained for the polysiloxane modified
with azophenol and amine containing a long hydrocarbon segment. In the other cases, only a partially disaggregation process
takes place. 相似文献
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Groneberg David A. Klingelhöfer Doris Brüggmann Dörthe Scutaru Cristian Fischer Axel Quarcoo David 《Scientometrics》2019,121(1):451-478
Scientometrics - Strategies employing information science and scientometric approaches were introduced to science policy and management over the past decades. As a rapidly evolving field, new... 相似文献
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C Cantemir C Cozmei B Scutaru S Nicoara E Carasevici 《Canadian Metallurgical Quarterly》1997,93(2-3):87-94
The p53 expression in peripheral lymphocytes of rats chronically exposed to atrazine was investigated. The experiment was performed in female Wistar rats. Atrazine was administrated in different doses (2.7 and 5.4 mg/kg body weight), each dose once a day, 5 days per week, for 6 and 12 months. The percentage of rats peripheral lymphocytes expressing p53 protein was evaluated by immunocytochemical technique, using a monoclonal antibody (clone PAb 122) against a common epitope, both for the wild type and the mutant p53 protein. The results indicate that in the atrazine long-term administration, the serum level of atrazine is associated with: (i) Significantly increased percentage of lymphocytes expressing p53 protein for all treated animals; (ii) different p53 intracellular compartmentalization (nucleus and cytoplasm), depending on dose and time of atrazine administration. The present study suggests that atrazine modifies the p53 expression, which could confirm the clastogenicity of this herbicide, and that the detection of the p53 protein may serve as a biomarker for the long-term exposure to atrazine. 相似文献
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Denis Mihaela Panaitescu Cristian Andi Nicolae Violeta Melinte Andreea Laura Scutaru Augusta Raluca Gabor Marius Stelian Popa Madalina Oprea Tinca Buruiana 《应用聚合物科学杂志》2021,138(37):50951
Composite materials from thermoplastic polyurethanes (TPUs) with biodegradable segments and microfibrillated cellulose (MFC) were developed as alternatives to traditional materials used in packaging or biomedical applications. Two TPUs were synthesized by the prepolymer method starting from different soft segments, poly(ε-caprolactone)/poly(butylene adipate) (PUBA) or poly(ε-caprolactone)/poly(ethylene oxide) (PUEO), and isophorone diisocyanate/aliphatic chain extender. Proton nuclear magnetic resonance (1H NMR) confirmed the structure and Fourier transform infrared spectroscopy (FTIR) along with scanning electron microscopy showed that the soft segments with different hydrophobicity led to a higher phase mixing in PUBA and improved microphase separation in PUEO. MFC was added in the TPUs with different soft segments to increase biocompatibility, strength, and degradation rate. A better thermal stability, a gradual increase of crystallinity and a better dispersion of MFC were noticed in PUEO composites compared to PUBA ones. The crystallinity increased with 78% and 50% in PUBA and PUEO composites with 5 wt% MFC compared to the neat polyurethanes showing the nucleating ability of MFC. In addition, the enhanced storage modulus, with 75% and 25% in PUEO and PUBA composites, highlighted the reinforcing efficiency of MFC. Therefore, the addition of MFC to the already synthesized TPUs allows tailoring the morphology and thermal properties of TPUs for industrial application. 相似文献
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