The addition of ions in micromolar (CaCl 2 or HCl) millimolar (NaCl) concentrations can change the morphology “crew-cut” aggregates amphiphilic block copolymers dilute solutions. In to spherical, rodlike, and univesicular lamellar aggregates, an unusual large compound vesicle be obtained from a single copolymer. Some features spontaneously formed vesicles may make them especially useful as vehicles for delivering drugs models biological cells. Gelation spherical micelle solution also induced...

A wide range of bilayer aggregates, among them tubules, vesicles, large compound vesicles (LCVs), and lamellae, were prepared from various polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers, studied by transmission electron microscopy (TEM). The preparation method involved copolymer dissolution in DMF at room temperature, followed the addition water. In addition, it was found that aggregates morphologies can be an identical block changing solvent to a water−DMF mixture,...

Block ionomer complexes formed between the block copolymers containing poly(sodium methacrylate) (PMANa) and poly(ethylene oxide) (PEO) segments poly(N-ethyl-4-vinylpyridinium bromide) (PEVP) were investigated. The data obtained suggest that (i) these systems form water-soluble stoichiometric complexes; (ii) are stable in a much broader pH range compared to polyelectrolyte prepared from homopolymers; (iii) they self-assemble core of micelle comprised neutralized polyions, surrounded by PEO...

This study demonstrates high contrast and sensitivity by designing a dual-emissive hydrogel particle system, whose two emissions respond to pH temperature strongly independently. It describes the photoluminescence (PL) response of poly(N-isopropylacrylamide) (PNIPAM)-based core/shell nanoparticles with dual emission, which is obtained emulsion polymerization potassium persulfate, consisting thermo- pH-responsive copolymers PNIPAM poly(acrylic acid) (PAA). A red-emission rare-earth complex...

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTMultiple Morphologies in Aqueous Solutions of Aggregates Polystyrene-block-poly(ethylene oxide) Diblock CopolymersKui Yu and Adi EisenbergView Author Information Department Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, Canada H3A 2K6 Cite this: Macromolecules 1996, 29, 19, 6359–6361Publication Date (Web):September 9, 1996Publication History Received12 March 1996Revised21 June...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSpontaneous Formation of Vesicles from Complexes Block Ionomers and SurfactantsA. V. Kabanov, T. K. Bronich, A. Yu, EisenbergView Author Information Department Pharmaceutical Sciences University Nebraska Medical Center Omaha, 68198 Polymer Sciences, Moscow State 119899, Russia Chemistry, McGill Montreal, Quebec, Canada H3A 2K6 Cite this: J. Am. Chem. Soc. 1998, 120, 38, 9941–9942Publication Date (Web):September 10, 1998Publication History...

Several novel morphologies of "crew-cut" aggregates have been prepared from highly asymmetric diblock copolymers polystyrene-b-poly(ethylene oxide) (PS-b-PEO) and polystyrene-b-poly(acrylic acid) (PS-b-PAA) in dilute solution. The include simple, circular, interconnected tubules, large compound rods, a structure bicontinuous branched short spheres with protruding porous spheres, as well containing combined morphologies. Some these structures are biomimetic. Branched rods appear to be...

Complexes from poly(ethylene oxide)-b-poly(sodium methacrylate) (PEO-b-PMANa) and N-alkylpyridinium bromides are water soluble, in marked contrast to those poly(sodium methacrylate). These systems studied using potentiometric titration, microcalorimetry, ζ-potential measurement, light scattering electron microscopy. Three regions (A−C) observed with a complex PEO-b-PMANa cetylpyridinuim bromide (C16PyBr) when the composition of mixture (Z = [C16PyBr]/[COO-]) is varied. (A) At Z < 1 C16PyBr...

Three families of colloidal CdSe magic-sized nanocrystals (MSNs) exhibiting bright bandgap photoluminescence (PL) with narrow full width at half-maximum (fwhm) on the order ca. 10 nm were synthesized in pure form. This noninjection one-pot synthetic approach uses cadmium acetate dihydrate (Cd(OAc)2·2H2O) and elemental selenium as Cd Se source compounds, respectively, while a fatty acid surface ligands 1-octadecene (ODE) reaction medium. All these chemicals loaded room temperature flask, low...

Abstract Little is known about the induction period before nucleation and growth of colloidal semiconductor quantum dots. Here, we introduce an approach that allows us to probe intermediates present in period. We show this itself exhibits distinct stages with evolution intermediates, first without then formation covalent bonds between metal cations chalcogenide anions. The are optically invisible toluene, while covalent-bonded become visible as magic-size clusters when a primary amine added....

Hydroxyapatite nanoparticles (HA NPs) have been acknowledged for their benign biocompatibility and proliferation inhibition effect on tumor cells, attracting considerable attention therapeutics without late effects. However, unnoticeable cytotoxicity of HA NPs limited the final clinical therapeutic efficacy. Herein, a two-phase synthetic approach was developed to synthesize sphere-like by varying conventional growth habit precipitate. We present our in vitro vivo experimental evidence that...

Abstract Structural isomerism of colloidal semiconductor nanocrystals has been largely unexplored. Here, we report one pair structural isomers identified for which exhibit thermally-induced reversible transformations behaving like molecular isomerization. The two are CdS magic-size clusters with sharp absorption peaks at 311 and 322 nm. They have identical cluster masses, but slightly different structures. Furthermore, their interconversions follow first-order unimolecular reaction kinetics....

Atomically defined, zero-dimensional magic-size clusters play pivotal roles in the nucleation and growth of semiconductor nanocrystals. Thus, they provide new opportunities to understand control reactions beyond classical theory employ these colloidal synthesis increasingly complex anisotropic nanomaterials with atomic level monodispersity. Both challenges require reliable determination exact structure size ultrasmall metastable nanoclusters. In this Perspective, we review discuss current...

A fundamental understanding of formation pathways is critical to the controlled synthesis colloidal semiconductor nanocrystals. As ultrasmall-size quantum dots (QDs) sometimes emerge in reactions along with magic-size clusters (MSCs), distinguishing their individual pathway evolution important, but has proven difficult. To decouple QDs and MSCs, an unconventional, selective approach been developed, a two-pathway model that provides production selectivity. For on-demand either ultrasmall or...

Abstract Metal‐based nanoparticles, especially gadolinium, manganese, and iron, have gained ground in the research of magnetic resonance imaging (MRI) contrast agents. Over years, agents based on these paramagnetic superparamagnetic nanomaterials merited keen attention biomedical field due to their desired properties such as sizeable susceptibility, tunable size, easy surface functionalization, low toxicity, etc. Gadolinium‐based chelates are traditional MRI clinic but require improved...

This study investigates the high-temperature oxidation behavior and performance of TA15 Ti alloy subjected to 500 800 °C service conditions. The process, microstructural evolution, mechanical property changes, comprehensive were analyzed. At °C, developed a distinctive blue-colored surface primarily composed Ti6O, indicating slow growth rate oxide layer. In contrast, condition led severe with notable TiO2 Al2O3 phases extensive peeling Microstructural analysis revealed that at there was...

A polystyrene−poly(ethylene oxide) containing diblock copolymer, when spread at the air/water interface, spontaneously forms surface aggregates. This aggregation is shown to be neither compression-induced, associated with micellization in spreading solvent, nor induced by Langmuir−Blodgett film transfer process. We have previously found that such two-dimensional occurs for copolymers a polystyrene block and hydrophilic of quaternized poly(vinylpyridine), poly(tert-butyl acrylate),...

Colloidal type II CdTe/CdSe nanocrystals were synthesized by sequential addition of a tri-n-octylphosphine telluride (TOPTe)/TOP solution and several shell-precursor solutions to CdO/TOP solution; the consisted CdO TOPSe in TOP. For growth CdTe core, TOPTe/TOP was swiftly added at higher temperature (300 degrees C) than (250 C). CdSe shell, contrast, CdO/TOPSe/TOP slowly CdTe/TOP lower (200-240 The temporal evolution optical properties growing core-shell monitored detail. During exhibited...

A readily synthesized dipeptide shows unprecedented gelation behavior when dispersed and submitted to ultrasound in nonsolvents. SEM FFEM revealed spectacular shape changes from a sheet-like material into highly interconnected fiber network ribbons while the maintains an anti conformation inside β-sheets at molecular scale.

Colloidal photoluminescent CdSeS quantum dots (QDs) were readily prepared via a noninjection, one-pot approach, with air-stable compounds cadmium acetate dihydrate (Cd(OAc)2·2H2O), elemental selenium (Se), and sulfur (S) as Cd, Se, S source compounds, respectively. The homogeneously alloyed QDs synthesized at 240 °C in reaction flask containing the together myristic acid, 2,2′-dithiobisbenzothiazole (MBTS), 1-octadecene (ODE). All of these chemicals loaded room temperature this newly...

High-quality colloidal photoluminescent (PL) ZnCdS quantum dots (QDs) with gradient distribution of components, consisting Cd-rich inner cores and Zn-rich outer shells, were synthesized via a noninjection one-pot approach. This newly developed synthetic approach uses zinc stearate (Zn(St)2), cadmium acetate dihydrate (Cd(OAc)2·2H2O), elemental sulfur as Zn, Cd, S source compounds, respectively. The growth the cubic-structured QDs was carried out at 240 °C in reaction flask together stearic...

Abstract Colloidal semiconductor quantum dots (QDs) have been well appreciated for their potential in nanophotonics with an unprecedented impact various areas, including light emitting diodes (LEDs) and solar cells. There is outstanding demand on the control of size distribution applications, rational design supported by fundamental understanding nucleation growth. This Research News introduces recent advances synthesis colloidal CdSe magic‐sized nuclei (MSN) exhibiting sharp bandgap...

We report our newly developed low-temperature synthesis of colloidal photoluminescent (PL) CuInS2 nanocrystals (NCs) and their in vitro vivo imaging applications. With diphenylphosphine sulphide (SDPP) as a S precursor made from elemental diphenylphosphine, this is noninjection based approach 1-dodecanethiol (DDT) with excellent synthetic reproducibility large-scale capability. For typical copper iodide (CuI) Cu source indium acetate (In(OAc)3) an In source, the growth temperature was low...

Colloidal photoluminescent (PL) PbS nanocrystals have attracted a lot of attention in various applications such as bioimaging and optical telecommunications due to their tunable bandgap the near-infrared region electromagnetic spectrum. Hot-injection processes seem be best engineer high-quality nanocrystals. However, there is limited body literature documented on syntheses, with little information synthetic parameters affecting properties product. Moreover, small large greater than 1.38 eV...

CdS magic-sized nanocrystals (MSNs) exhibiting both band gap absorption and emission at 378 nm with a narrow bandwidth of approximately 9 quantum yield (QY) 10% (total QY 28%, in hexane) were synthesized via one-pot noninjection approach. This MSN ensemble is termed as Family 378. It has been acknowledged that dots (MSQDs) are single-sized, only homogeneous broadening contributes to their bandwidth. The synthetic approach developed ready highly reproducible. formation the MSQDs was carried...