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181.
Jakub K. Wegrzyn Tim Stephan Ryan Lau Robert B. Grubbs 《Journal of polymer science. Part A, Polymer chemistry》2005,43(14):2977-2984
Amphiphilic poly(ethylene oxide)‐block‐poly(isoprene) (PEO‐b‐PI) diblock copolymers were prepared by nitroxide‐mediated polymerization of isoprene from alkoxyamine‐terminal poly(ethylene oxide) (PEO). PEO monomethyl ether (Mn ≈ 5200 g/mol) was functionalized by esterification with 2‐bromopropionyl bromide with subsequent copper‐mediated replacement of the terminal bromine with 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐nitroxide. The resulting PEO‐alkoxyamine macroinitiator was used to initiate polymerization of isoprene in bulk and in solution at 125 °C to yield PEO‐b‐PI block copolymers with narrow molecular weight distributions (Mw/Mn ≤ 1.1). Polymerizations were first order in isoprene through 35% conversion. Micellar aggregates of PEO‐b‐PI in aqueous solution were crosslinked by treatment with a water‐soluble redox initiating system, and persistent micellar structures were observed in the dry state by AFM. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2977–2984, 2005 相似文献
182.
RuS2 nanoparticles, smaller than 3 nm in diameter, were prepared by H2S gas injection into the AOT/isooctane reverse micellar solution containing RuCl3 aqueous solution. The nanoparticle size was found to be independent of the Wo (water content) value of the reverse micellar system, as shown by TEM observation. The recovery and immobilization of the RuS2 nanoparticles from reverse micelles onto thiol-modified polystyrene particles (PSt-SH) were successfully carried out, by the addition of PSt-SH into the reverse micellar solution under conditions of mild stirring. The resulting composites, PSt-RuS2, showed photocatalytic activity for H2 generation form aqueous solution containing 2-propanol and Na2SO3 as sacrificial electron donors. 相似文献
183.
Katherine B. Aubrecht Robert B. Grubbs 《Journal of polymer science. Part A, Polymer chemistry》2005,43(21):5156-5167
Amphiphilic BuO‐(PEO‐stat‐PPO)‐block‐PLA‐OH diblock and MeO‐PEO‐block‐(PEO‐stat‐PPO)‐block‐PLA‐OH triblock copolymers incorporating thermoresponsive poly(ethylene oxide‐stat‐propylene oxide) (PEO‐stat‐PPO) blocks were prepared by ring‐opening polymerization of lactide (LA) initiated by macroinitiators formed from treating BuO‐(PEO‐stat‐PPO)‐OH and MeO‐PEO‐block‐(PEO‐stat‐PPO)‐OH with AlEt3. MeO‐PEO‐block‐(PEO‐stat‐PPO)‐OH was prepared by coupling MeO‐PEO‐OH and HO‐(PEO‐stat‐PPO)‐OH, followed by chromatographic purification. The cloud points of 0.2% aqueous solutions are between 36 and 46 °C for the diblock copolymers that contain a 50 wt % EO thermoresponsive block and 78 °C for the triblock copolymer that contains a 75 wt % EO thermoresponsive block. Variable temperature 1H NMR spectra recorded on D2O solutions of the diblock copolymers display no PLA resonances below the cloud point and fairly sharp PLA resonances above the cloud point, suggesting that desolvation of the thermoresponsive block increases the miscibility of the two blocks. Preliminary characterization of the micelles formed in aqueous solutions of BuO‐(PEO‐stat‐PPO)‐block‐PLA‐OH conducted using laser scanning confocal microscopy and pulsed gradient spin echo NMR point to significant changes in the size of the micellar aggregates as a function of temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5156–5167, 2005 相似文献
184.
Volumetric and transport properties of aerosol-OT reversed micelles containing light and heavy water
Alessandro D'Aprano Ines D. Donato Mario Goffredi Vincenzo Turco Liveri 《Journal of solution chemistry》1992,21(4):323-332
Densities and viscosities of sodium bis(2-ethylhexyl) sulfosuccinate (AOT in-heptane system containing light and heavy water,
as a function of the molar ratio R (R=[H2O or D2O]/[AOT]) were measured at 0, 5, 25 and 40°C. At low R values, the apparent molar volume of deuterium oxide is smaller than
that of light water. The difference is related to the strength of the hydrogen bonding H2O and D2O. The viscosities of both H2O-AOT-n-heptane and D2O-AOT-n-heptane systems were explained in terms of intermicellar interactions mainly governed by hydration of the head groups
of AOT. 相似文献
185.
The steady state fluorescence measurements have been carried out for the binary mixtures of poly(ethylene glycol) alkyl ethers (C
i
E
j
) with series of monomeric cationic (MC), zwitterionic (ZI), and phosphonium cationic (PC) surfactants over the whole mole fraction range by using pyrene as fluorescence probe. The cmc values for all the binary mixtures, thus, determined have been further evaluated by using the regular solution theory. The various micellar parameters such as regular solution interaction parameter (β), micropolarity (I
1/I
3), and mean micelle aggregation number (N
agg) have been determined. A strong influence of hydrophobicity of both nonionic as well as cosurfactant (CS) components has been observed on the nature of mixed micelles. The presence of bulky head groups of PC surfactants significantly contributes towards the unfavorable mixing. 相似文献
186.
Synthesis and Design of Aggregation‐Induced Emission Surfactants: Direct Observation of Micelle Transitions and Microemulsion Droplets 下载免费PDF全文
Dr. Weijiang Guan Dr. Wenjuan Zhou Prof. Dr. Chao Lu Prof. Dr. Ben Zhong Tang 《Angewandte Chemie (International ed. in English)》2015,54(50):15160-15164
The direct visualization of micelle transitions is a long‐standing challenge owing to the intractable aggregation‐caused quenching of light emission in the micelle solution. Herein, we report the synthesis of a surfactant with a tetraphenylethene (TPE) core and aggregation‐induced emission (AIE) characteristics. The transition processes of surfactant micelles and the microemulsion droplets (MEDs) formed by the surfactant with a TPE core were clearly visualized by a high‐contrast fluorescence imaging method. The fluorescence intensity of the MEDs decreased as the size of MEDs increased as a result of weakening of the restriction of intramolecular rotation (RIR). The results of this study deepen our understanding of micelle‐transition processes and provide solid evidence in favor of the hypothesis that the AIE phenomenon has its origin in the RIR of fluorophores in the aggregate state. 相似文献
187.
Synthesis of Nitrogen‐Doped Mesoporous Carbon Spheres with Extra‐Large Pores through Assembly of Diblock Copolymer Micelles 下载免费PDF全文
Jing Tang Dr. Jian Liu Dr. Cuiling Li Yunqi Li Prof. Moses O. Tade Prof. Sheng Dai Prof. Yusuke Yamauchi 《Angewandte Chemie (International ed. in English)》2015,54(2):588-593
The synthesis of highly nitrogen‐doped mesoporous carbon spheres (NMCS) is reported. The large pores of the NMCS were obtained through self‐polymerization of dopamine (DA) and spontaneous co‐assembly of diblock copolymer micelles. The resultant narrowly dispersed NMCS possess large mesopores (ca. 16 nm) and small particle sizes (ca. 200 nm). The large pores and small dimensions of the N‐heteroatom‐doped carbon spheres contribute to the mass transportation by reducing and smoothing the diffusion pathways, leading to high electrocatalytic activity. 相似文献
188.
189.
190.
New approach for producing fluorescent gold nanoparticles: Poly(ethylene oxide) homopolymers as reductants in the micelles of amphiphilic fluorosilicone‐containing block copolymers 下载免费PDF全文
Jiawen Zhang Lingmin Yi Kai Xu Jing Li Dongzhi Lai 《Journal of polymer science. Part A, Polymer chemistry》2015,53(20):2320-2325