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101.
Eleanor Raphael Matthew J. Derry Michael Hippler Steven P. Armes 《Chemical science》2021,12(36):12082
Polymerization-induced self-assembly (PISA) is exploited to design hydrogen-bonded poly(stearyl methacrylate)-poly(benzyl methacrylate) [PSMA-PBzMA] worm gels in n-dodecane. Using a carboxylic acid-based RAFT agent facilitates hydrogen bonding between neighboring worms to produce much stronger physical gels than those prepared using the analogous methyl ester-based RAFT agent. Moreover, tuning the proportion of these two types of end-groups on the PSMA chains enables the storage modulus (G′) of a 20% w/w worm gel to be tuned from ∼4.5 kPa up to ∼114 kPa. This is achieved via two complementary routes: (i) an in situ approach using binary mixtures of acid- and ester-capped PSMA stabilizer chains during PISA or (ii) a post-polymerization processing strategy using a thermally-induced worm-to-sphere transition to mix acid- and ester-functionalized spheres at 110 °C that fuse to form worms on cooling to 20 °C. SAXS and rheology studies of these hydrogen-bonded worm gels provide detailed insights into their inter-worm interactions and physical behavior, respectively. In the case of the carboxylic acid-functionalized worms, SAXS provides direct evidence for additional inter-worm interactions, while rheological studies confirm both a significant reduction in critical gelation concentration (from approximately 10% w/w to 2–3% w/w) and a substantial increase in critical gelation temperature (from 41 °C to 92 °C). It is remarkable that a rather subtle change in the chemical structure results in such improvements in gel strength, gelation efficiency and gel cohesion.Carboxylic acid-capped diblock copolymer worms are prepared in n-dodecane via polymerization-induced self-assembly. Varying the proportion of terminal carboxylic acid groups modulates the inter-worm H-bonding interactions and hence the gel modulus. 相似文献
102.
Non-peripherally octakis-substituted phthalocyanines (npPc’s), MPc(C12H25)8 with M = 2H (3) or Zn (4), as well as peripherally octakis-substituted phthalocyanines (pPc’s) with M = Zn (6), Mg (7) and 2H (8), were synthesized by cyclotetramerization of 3,6- (2) or 4,5-bis(dodecyl)phthalonitrile (5), template cyclotetramerization of precursor phthalonitriles in the presence of Zn or Mg, metal insertion into metal-free phthalocyanines, and removal of Mg or Zn from the phthalocyaninato coordination cavity. The more effective synthetic route towards pPc 8 was demetalation of 7. npPc’s were more soluble than pPc’s. The Q-band λmax of npPc’s was red-shifted with ca. 18 nm, compared to that of pPc’s. X-ray photoelectron spectroscopy (XPS) differentiated between N–H, Nmeso and Ncore nitrogen atoms for metal-free phthalocyanines. Binding energies were ca. 399.6, 398.2 and 397.7 eV respectively. X-ray photoelectron spectroscopy (XPS) also showed zinc phthalocyanines 4 and 6 have four equivalent Nmeso and four equivalent N–Zn core nitrogens. In contrast, the Mg phthalocyanine 7 has two sets of core N atoms. One set involves two Ncore atoms strongly coordinated to Mg, while the other encompasses the two remaining Ncore atoms that are weakly associated with Mg. pPc’s 6, 7, and 8 have cyclic voltammetry features consistent with dimerization to form [Pc][Pc+] intermediates upon oxidation but npPc’s 3 and 4 do not. Metalation of metal-free pPc’s and npPc’s shifted all redox potentials to lower values. 相似文献
103.
Ellen L. Heeley Darren J. Hughes Eleanor M. Crabb James Bowen Oier Bikondoa Beatriz Mayoral Tony McNally 《Journal of Polymer Science.Polymer Physics》2017,55(2):132-137
Here, the confirmation of an oriented nanohybrid shish‐kebab (NHSK) crystalline structure in a series of composites of poly(ethylene terephthalate) (PET) and multiwall carbon nanotubes (MWCNTs) is reported. The combined use of small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and thermal analysis has been used to investigate the morphology development in PET‐MWCNT nanocomposites under hot isothermal crystallization conditions. The MWCNTs act as both heterogeneous nucleating agents and surfaces (oriented shish structures) for the epitaxial growth of PET crystallites (kebabs) giving an oriented crystalline morphology. In contrast, the PET homopolymer does not show any residual oriented crystalline morphology during isothermal crystallization but gave a sporadic nucleation of a classic unoriented lamellar structure with slower crystallization kinetics. The results provide a valuable insight into the role of MWCNTs as nanoparticulate fillers in the morphology development and subsequent modification of physical properties in engineering polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 132–137 相似文献
104.
Inside Back Cover: Polyoxometalate‐Mediated One‐Pot Synthesis of Pd Nanocrystals with Controlled Morphologies for Efficient Chemical and Electrochemical Catalysis (Chem. Eur. J. 14/2015)
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105.
Fast quantitative determination of methylphenidate levels in rat plasma and brain ex vivo by MALDI‐MS/MS
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Anne Arnold Markus Persike Jan Gorka Eleanor J Dommett Martina Zimmermann Michael Karas 《Journal of mass spectrometry : JMS》2015,50(8):963-971
This study presents a simple and sensitive high‐throughput matrix‐assisted laser desorption/ionization time‐of‐flight tandem mass spectrometry (MALDI‐MS/MS) method for ex vivo quantification of methylphenidate (MPH) in rat plasma and brain. The common MALDI matrix alpha‐cyano‐4‐hydroxycinnamic acid was used to obtain an optimal dried droplet preparation. For method validation, standards diluted in plasma and brain homogenate prepared from untreated (control) rats were used. MPH was quantified within a concentration range of 0.1–40 ng/ml in plasma and 0.4–40 ng/ml in brain homogenate with an excellent linearity (R2 ≥ 0.9997) and good precision. The intra‐day and inter‐day accuracies fulfilled the FDA's ±15/20 critera. The recovery of MPH ranged from 93.8 to 98.5% and 87.2 to 99.8% in plasma and homogenate, respectively. We show that MPH is successfully quantified in plasma and brain homogenate of rats pre‐treated with this drug using the internal standard calibration method. By means of this method, a linear correlation between plasma and brain concentration of MPH in rodents pre‐treated with MPH was detected. The simple sample preparation based on liquid‐liquid extraction and MALDI‐MS/MS measurement requires approximately 10 s per sample, and this significantly reduces analysis time compared with other analytical methods. To the best of our knowledge, this is the first MALDI‐MS/MS method for quantification of MPH in rat plasma and brain. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
106.
Niamh Holland Patrick Duggan Eleanor Owens Wayne Cummins June Frisby Helen Hughes Peter McLoughlin 《Analytical and bioanalytical chemistry》2008,391(4):1245-1253
A powerful method utilising direct probe thermal desorption GC–MS is presented for the study of molecularly imprinted polymers
(MIPs). A series of 2-aminopyridine (2-apy)-imprinted methacrylic acid–ethyleneglycol dimethacrylate (MAA–EGDMA) copolymers
were prepared under identical conditions but with varying amounts of EGDMA (crosslinking monomer). The use of appropriate
temperature programmes permitted template removal, and the subsequent assessment of polymer affinity and specificity, all
of which were found to be dependent on polymer composition and morphology. The system was sufficiently sensitive to identify
a specific response of imprinted polymers over nonimprinted counterparts. Correlations were found to exist between thermal
desorption analysis and solution phase binding, which was assessed by UV spectroscopy, where specificity was found to diminish
with decreasing EGDMA concentration. This was attributed to the increased number of free carboxyl groups in those polymers
containing a lower percentage of EGDMA. Thermal desorption profiles obtained for the analyte were found to be unaffected by
the physical and chemical properties of the solvent used for analyte reloading.
An erratum to this article can be found at 相似文献
107.
108.
109.
Thanks to their excellent mechanical properties as well as interesting electrical characteristics, carbon nanotubes are among the most widely used materials for the study of electromechanical properties. This review paper presents the physical properties and the potential applications of carbon nanotube based nanoelectromechanical devices. We present an overview of fabrication methods followed by a discussion of the physical properties of CNT-NEMS. Finally some potential applications are discussed. 相似文献
110.
The voltammetric behaviour of 2,6-dichloro-p-aminophenol (PAP) in aqueous solution at an edge plane pyrolytic graphite electrode was explored and its sensitivity to additions
of substituted phenols examined. Proof of concept is shown for the electrochemical adaptation of the Gibbs reaction, where
reaction of the oxidised form of PAP with substituted phenols provides an indirect methodology for the analytical detection
of these compounds. This indirect protocol provides an attractive alterative to the direct electrochemical oxidation of phenolic
compounds, since the latter is plagued by electrode passivation, leading to low sensitivity. It is observed that phenol, 4-phenoxyphenol,
methylphenol (para and meta), nitrophenol and most importantly, tetrahydrocannabinol, can be detected voltammetrically. Such
a protocol is particularly attractive for roadside testing for cannabis in drug drivers. 相似文献