Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 38
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Langmuir ; 37(35): 10461-10468, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34431681

RESUMO

A colloidal nanocrystal cluster (CNC) is a hierarchical nanostructure formed by clustering several nanocrystals into one nano-ensemble, which may exhibit unique optical or catalytic properties different from individual nanocrystals owing to the mutual interactions among neighboring component nanocrystals. However, there is still no universal synthetic route that could be applicable to diverse material compositions with precisely controlled hierarchical structures (i.e., nanocrystal number density, component nanocrystal size, and overall diameter of the CNC) up to now. Herein, a general and novel synthetic strategy was reported for crafting a wide range of inorganic CNCs (i.e., noble metal, semiconductor, and metal oxide) via utilizing amphiphilic star-like poly(4-vinylpyridine)-block-polystyrene diblock copolymers as nanoreactors prepared by sequential atom transfer radical polymerization. The hierarchical structure of rationally designed CNCs could be readily tailored by varying the P4VP molecular weight of star-like nanoreactors and the parameter optimization during the CNC preparation process, which was inaccessible by conventional synthetic methods.

2.
ACS Appl Mater Interfaces ; 13(33): 39806-39818, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34387459

RESUMO

Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, water-soluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 as the soft template, AgNO3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (Dh in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO3/acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (-), the MIC value is as low as 5 µg/mL (0.36 µg/mL of Ag), while for S. aureus (+), the value is around 10 µg/mL (0.72 µg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.


Assuntos
Antibacterianos/efeitos adversos , Antibacterianos/química , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/metabolismo , Boroidretos/química , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Polímeros/química , Compostos de Amônio Quaternário/química , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície , Nanomedicina Teranóstica
3.
J Colloid Interface Sci ; 600: 421-429, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34023703

RESUMO

Multi-stimuli responsive fluorescence probe could pave the way for monitoring more complex environmental changes. Here we prepared multifunctional nanoparticle Fe3O4@SiO2@P(DMAEMA-co-TPEE), which displayed yolk-shell morphology with well-defined polymer brush. With superparamagnetic Fe3O4 component and pH/temperature dual sensitive PDMAEMA polymer brush, the as prepared nanoparticles (YS-NPs) exhibited as multi-stimuli responsive fluorescence probe for real-time visual monitoring of environmental changes such as magnetic field, temperature and pH. Such YS-NPs could also be applied as a sensitive detector for CO2 in aqueous solution. Notably, the solution of YS-NPs showed high colloidal stability during the environmental changes, and surface aggregation-induced emission (S-AIE) was proposed for the aggregation of TPE residue on the surface of YS-NPs.


Assuntos
Nanocompostos , Nanopartículas , Polímeros , Temperatura
4.
Adv Sci (Weinh) ; 8(14): e2100075, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34021718

RESUMO

With the increasing demand for detection accuracy and sensitivity, dual-band polarimetric image sensor has attracted considerable attention due to better object recognition by processing signals from diverse wavebands. However, the widespread use of polarimetric sensors is still limited by high noise, narrow photoresponse range, and low linearly dichroic ratio. Recently, the low-dimensional materials with intrinsic in-plane anisotropy structure exhibit the great potential to realize direct polarized photodetection. Here, strong anisotropy of 1D layered bismuth sulfide (Bi2 S3 ) is demonstrated experimentally and theoretically. The Bi2 S3 photodetector exhibits excellent device performance, which enables high photoresponsivity (32 A W-1 ), Ion /Ioff ratio (1.08 × 104 ), robust linearly dichroic ratio (1.9), and Hooge parameter (2.0 × 10-5 at 1 Hz) which refer to lower noise than most reported low-dimensional materials-based devices. Impressively, such Bi2 S3 nanowire exhibits a good broadband photoresponse, ranging from ultraviolet (360 nm) to short-wave infrared (1064 nm). Direct polarimetric imaging is implemented at the wavelengths of 532 and 808 nm. With these remarkable features, the 1D Bi2 S3 nanowires show great potential for direct dual-band polarimetric image sensors without using any external optical polarizer.

5.
J Phys Chem Lett ; 12(13): 3456-3463, 2021 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-33792312

RESUMO

The past few years witnessed the rapid development of bottom-up synthesis strategies for preparing various nanostructures (i.e., nanoparticles, nanorods, nanowires, etc.) with distinct morphology-dependent properties. In this study, we reported a facile and efficient synthesis method for preparing anatase titanium dioxide (TiO2) nanorings based on multiarm, starlike amphiphilic polystyrene-b-poly(acrylic acid) (PS-b-PAA) diblock copolymers as nanoreactors which were prepared via a sequential atom-transfer radical polymerization (ATRP) technique followed by the conversion of polystyrene-b-poly(tert-butyl acrylate) (PS-b-PtBA) to PS-b-PAA. The outer PAA block of nanoreactors possessed carboxylic acid groups which could coordinate with a titanium precursor followed by high-temperature calcination to form crystalline TiO2 nanorings. The living nature of ATRP enabled the precise preparation of starlike diblock copolymer nanoreactors with a controlled length of each block (i.e., PtBA and PS), thereby tailoring the inner diameter and wall thickness of the resulting TiO2 nanorings, which were inaccessible to conventional routes.

6.
ACS Appl Mater Interfaces ; 13(13): 15448-15458, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33769030

RESUMO

The ambient stability and processability of organic solar cells (OSCs) are important factors for their commercialization. Herein, we selected four benzo[1,2-b:4,5-b']difuran (BDF) polymers and two electron acceptors to examine the role of photovoltaic materials in the ambient stability. The investigations revealed that the MoOx layer is the detrimental factor for the ambient stabilities. The penetration of MoOx into the active layer and their interactions will strengthen the interface and form a favorable contact, hence leading to the increased photovoltaic performance, in which the efficiency loss induced by air was balanced out. As such, these BDF polymer-based non-fullerene (NF) OSCs possessed very promising ambient stabilities even after ∼1000 h with the almost maintained power conversion efficiencies (PCEs). These results drive us to further investigate the ambient processability of these NF-OSCs. The PCEs from the devices processed under ambient condition only possessed 0.3-2% loss compared to those devices under inert conditions, which suggest the significant potentials of BDF polymers to develop highly efficient and stable NF-OSCs for the practical applications.

7.
Angew Chem Int Ed Engl ; 60(13): 7259-7266, 2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33393190

RESUMO

Approaches to achieve stable perovskite nanocrystals (PNCs) of interest, in particular those with large structural anisotropy, through protective coating of the inorganic shell at a single-nanocrystal (NC) level are comparatively few and limited in scope. Reported here is a robust amphiphilic-diblock-copolymer-enabled strategy for crafting highly-stable anisotropic CsPbBr3 nanosheets (NSs) by in situ formation of a uniform inorganic shell (1st shielding) that is intimately ligated with hydrophobic polymers (2nd shielding). The dual-protected NSs display an array of remarkable stabilities (i.e., thermal, photostability, moisture, polar solvent, aliphatic amine, etc.) and find application in white-light-emitting diodes. In principle, by anchoring other multidentate amphiphilic polymer ligands on the surface of PNCs, followed by templated-growth of shell materials of interest, a rich variety of dual-shelled, multifunctional PNCs with markedly improved stabilities can be created for use in optics, optoelectronics, and sensory devices.

8.
Chem Commun (Camb) ; 57(10): 1250-1253, 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33427260

RESUMO

Size and surface functionality are critically important for organic-inorganic hybrid semiconductive nanocomposites in terms of stable photoelectrochemical properties and superior device performance. The ability of reversible deactivation radical polymerization to control the chain length and dispersity of polymers is herein extended to the tailor-made synthesis of nanocomposites with tunable size, distribution, and surface coating. This is exemplified by the fabrication of cadmium selenide (CdSe) quantum dots (QDs) with uniform sizes from 2 to 10 nm that are intimately coated with poly(3-hexylthiophene) (i.e., CdSe@P3HT).

9.
Int J Nanomedicine ; 15: 6153-6165, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32884269

RESUMO

Background: Although pH and redox sensitiveness have been extensively investigated to improve therapeutic efficiency, the effect of disulfide bonds location and pH-triggered charge-reversal on cascade-targeting still need to be further evaluated in cancer treatment with multi-responsive nanoparticles. Purpose: The aim of this study was to design multi-responsive DOX@MSNs-COS-NN-CMC, DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS and systematically investigate the effects of disulfide bonds location and charge-reversal on the cancer cell specificity, endocytosis mechanisms and antitumor efficiency. Results: In vitro drug release rate of DOX@MSNs-COS-SS-CMC in tumor environments was 7-fold higher than that under normal physiological conditions after 200 h. Furthermore, the fluorescence intensity of DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS was 1.9-fold and 1.3-fold higher than free DOX at pH 6.5 and 10 mM GSH. In addition, vesicular transport might be a factor that affects the uptake efficiency of DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS. The clathrin-mediated endocytosis and endosomal escape of DOX@MSNs-COS-SS-CMC enhanced cellular internalization and preserved highly controllable drug release into the perinuclear of HeLa cells. DOX@MSNs-COS-SS-CMC exhibited a synergistic chemotherapy in preeminent tumor inhibition and less side effects of cardiotoxicity. Conclusion: The cascade-targeting of charge-reversal and disulfide bonds shielding would be a highly personalized strategy for cervical cancer treatment.


Assuntos
Doxorrubicina/administração & dosagem , Doxorrubicina/farmacologia , Sistemas de Liberação de Medicamentos/métodos , Nanopartículas Multifuncionais/química , Animais , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/farmacocinética , Antibióticos Antineoplásicos/farmacologia , Quitosana/química , Dissulfetos/química , Doxorrubicina/farmacocinética , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Endocitose/efeitos dos fármacos , Feminino , Glutationa/metabolismo , Células HeLa , Humanos , Camundongos Endogâmicos BALB C , Nanopartículas Multifuncionais/administração & dosagem , Oxirredução , Ensaios Antitumorais Modelo de Xenoenxerto
10.
ACS Appl Mater Interfaces ; 12(37): 42161-42168, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32840349

RESUMO

Silicon quantum dots (SiQDs) are explored for the first time as an efficient photocatalyst for visible-light-regulated reversible addition-fragmentation chain transfer (RAFT) polymerization. The fluorescence quenching confirmed the photoinduced electron transfer (PET) between SiQDs and RAFT reagents. Besides all features of controlled radical polymerization, the SiQDs catalyzed PET-RAFT polymerization also exhibit good temporal control, high chain-end fidelity, and versatility with diverse monomers. Moreover, amino-functionalized SiQDs can be easily coated on the surface of substrates (silicon wafer) owing to the electrostatic interaction, and play a dual role of polymer-substrate connector and photocatalyst for the surface-initiated PET-RAFT polymerization. The SiQD-coated wafer was also proved to be an efficient recycle photocatalyst for PET-RAFT polymerization.

11.
Langmuir ; 36(24): 6690-6697, 2020 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-32493013

RESUMO

We reported the synthesis of a well-defined hollow polymer nanoparticle derived from star-shaped unimolecular micelles. ß-Cyclodextrin was first applied as an efficient macroinitiator to prepare a star-shaped PCL via ring-opening polymerization (ROP). Then, the star-shaped PCL was modified to be a macro-RAFT agent for photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of S-Cl monomers. The prepared unimolecular micelles can be photocross-linked under UV irradiation after a simple nucleophilic substitution reaction, which made -Cl groups to be -N3 groups. After the selective removal of the PCL core, hollow polymer nanoparticles were achieved and exhibited to be a general nanoreactor strategy for the fabrication of nanocrystals with well-controlled architectures. Compared with unimolecular micelle templates, the nanocrystals prepared by hollow templates are absolutely pure as no polymer chains are embedded in the inorganic nanocrystals. In addition, by changing the concentration of the precursor, the structure of the nanocrystal can be changed from a normal spherical structure to a hollow structure.

12.
Mol Pharm ; 17(6): 1910-1921, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32223247

RESUMO

The surface charge of nanocarriers inevitably affects drug delivery efficiency; however, the cancer cell specificity, anti-inflammatory effects, and charge-reversal points remain to be further addressed in biomedical applications. The aim of this study was to comprehensively assess the cancer cell specificity of DOX-loaded mesoporous silica-chitosan oligosaccharide-carboxymethyl chitosan nanoparticles (DOX@MSNs-COS-CMC) in MCF-7 and HeLa cells, inhibit the production of inflammatory cytokines, and improve the drug accumulation in the tumor site. Intracellular results reveal that the retention time prolonged to 48 h in both HeLa and MCF-7 cells at pH 7.4. However, DOX@MSNs-COS-CMC exhibited a cell type-dependent cytotoxicity and enhanced intracellular uptake in HeLa cells at pH 6.5, due to the clathrin-mediated endocytosis and macropinocytosis in HeLa cells in comparison with the vesicular transport in MCF-7 cells. Moreover, Pearson's correlation coefficient value significantly decreased to 0.25 after 8 h, prompting endosomal escape and drug delivery into the HeLa nucleus. After the treatment of MSNs-COS-CMC at 200 µg/mL, the inflammatory cytokines IL-6 and TNF-α level decreased by 70% and 80%, respectively. Tumor inhibition of DOX@MSNs-COS-CMC was 0.4 times higher than free DOX, alleviating cardiotoxicity and inflammation in the HeLa xenograft tumor model. Charge-reversible DOX@MSNs-COS-CMC could be a possible candidate for clinical therapy of cervical carcinoma.


Assuntos
Anti-Inflamatórios/metabolismo , Quitosana/química , Neoplasias do Colo do Útero/metabolismo , Endocitose/fisiologia , Feminino , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Interleucina-6/metabolismo , Células MCF-7 , Modelos Biológicos , Fator de Necrose Tumoral alfa/metabolismo
13.
Chem Asian J ; 15(7): 1014-1017, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32012458

RESUMO

Aggregation-induced emission (AIE) technology has been demonstrated to be a facile approach for in-situ monitoring atom transfer radical polymerization (ATRP). A series of tertraphenyl ethylene (TPE)-containing α-bromo compounds were synthesized and applied as ATRP initiators. The photoluminescent (PL) emission of the polymerization system is proved to be sensitive to the local viscosity owing to the AIE characteristics of TPE. Linear relationships between the resulting molecular weight Mn and PL intensity were observed in several polymerization systems with different monomers, indicating the variability of this technique. Compared to physical blending, the chemical bonding of the TPE group in the chain end has higher sensitivity and accuracy to the polymer segments and the surrounding environment. This work promoted the combination of the AIE technique and controlled living radical polymerization, and introduced such an optical research platform to the ATRP polymerization process.

14.
ACS Appl Mater Interfaces ; 12(12): 14233-14243, 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32103662

RESUMO

Single pure organic molecular white light emitters (SPOMWLEs) are of significance as a new class of material for white lighting applications; however, few of them are able to emit white electroluminescence from organic light-emitting diodes. Herein, donor-π-acceptor conjugated emitters, 2PQ-PTZ and 4PQ-PTZ, were designed and synthesized as SPOMWLEs for white light emission considering the distinct advantages of their conformation isomers. The coexistence of conformational isomers in 2PQ-PTZ, which is the first experimental evidence of the coexisting quasi-axial and quasi-equatorial conformers, provides ideal flexibility to obtain white light emission from their simultaneous and well-separated fluorescence and thermally activated delayed fluorescence. With these remarkable properties, a 2PQ-PTZ-based white light-emitting diode (LED) with a CIE of (0.32, 0.34) and color rendering index (CRI) of 89 is demonstrated. Further, the white organic light-emitting diode (OLED) of 2PQ-PTZ exhibits a high external quantum efficiency (EQE) of 10.1%, which is the reported highest performance among SPOMWLE-based OLEDs.

15.
ACS Appl Mater Interfaces ; 11(39): 35914-35923, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31495172

RESUMO

The ON/OFF ratio and long-term stability are two important issues for flexible organic-inorganic hybrid perovskite (OHP) resistive random access memory (RRAM) for practical applications. In this work, polyvinylammonium (PVAm) is applied to partially replace methylamine ions (MA+) to fabricate the stable and flexible polymeric OHP RRAM devices, wherein PVAm acts as nucleation sites and the template for crystalline growth of MAPbI3 to tune the microscopic perovskite structure. Simultaneously, the multiple perovskite grain interfaces are strengthened through the long-carbochain polymeric backbone, hence producing a continuous and compact perovskite film. As a result, the PVAm-modified OHP RRAM device shows remarkable enhancement of the ON/OFF ratio, long-term stability, and flexibility compared with the unmodified OHP device. Specifically, the polymeric OHP device exhibits fast and stable nonvolatile resistive switching (RS) characteristics with an ON/OFF ratio of ∼105 and a set voltage of -0.45 V under ambient conditions. Also, the distinct multilevel RS behavior can be realized in this device by controlling the compliance current in the SET process. Additionally, the unsealed polymeric OHP device manifests the striking long-term stability, which can still maintain the stable memory performance after 1 year exposure to the humid and thermal ambient environment. Furthermore, the flexible polymeric OHP device was also fabricated and affords the excellent bending endurance behavior by showing a reproducible RS property over 100-cycle bending experiments. This work provides a new perovskite-based material design strategy of polymeric OHP for stable and flexible RRAM devices with the high ON/OFF ratio.

16.
ACS Appl Mater Interfaces ; 11(35): 32025-32037, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31398285

RESUMO

Photocatalytic CO2 reduction to solar fuel is a promising route to alleviate the ever-growing energy crisis and global warming. Herein, to enhance photoconversion efficiency of CO2 reduction, a series of direct Z-scheme composites consisting of ß-AgVO3 nanoribbons and InVO4 nanoparticles (InVO4/ß-AgVO3) are prepared via a facile hydrothermal method and subsequent in situ growth process. The prepared InVO4/ß-AgVO3 composites exhibit enhanced photocatalytic activity for reduction of CO2 to CO under visible-light illumination. A CO evolution rate of 12.61 µmol·g-1·h-1 is achieved over the optimized 20% In-Ag without any cocatalyst or sacrificial agent, which is 11 times larger than that yielded by pure InVO4 (1.12 µmol·g-1·h-1). Moreover, the CO selectivity is more than 93% over H2 production from the side reaction of H2O reduction. Significantly, based on the results of electron spin resonance (ESR) and in situ irradiated XPS tests, it is proposed that the synthesized InVO4/ß-AgVO3 catalysts comply with the direct Z-scheme transfer mechanism. Significantly improved photocatalytic activities for selective CO2 reduction could be primarily ascribed to effective separation of photoinduced electron-hole pairs and enhanced reducibility of photoelectrons at the conduction band of InVO4. This work provides a new insight for constructing highly efficient photocatalytic CO2 reduction systems toward solar fuel generation.

17.
Sci Rep ; 9(1): 1869, 2019 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-30755621

RESUMO

An unconventional but facile approach to prepare size-tunable core/shell ferroelectric/polymeric nanoparticles with uniform distribution is achieved by metal-free atom transfer radical polymerization (ATRP) driven by visible light under ambient temperature based on novel hyperbranched aromatic polyamides (HBPA) as a functional matrix. Cubic BaTiO3/HBPA nanocomposites can be prepared by in-situ polycondensation process with precursors (barium hydroxide (Ba(OH)2) and titanium(IV) tetraisopropoxide (TTIP)) of ferroelectric BaTiO3 nanocrystals, because precursors can be selectively loaded into the domain containing the benzimidazole rings. At 1200 °C, the aromatic polyamide coating of cubic BaTiO3 nanoparticles are carbonized to form carbon layer in the inert environment, which prevents regular nanoparticles from gathering. In addition, cubic BaTiO3 nanoparticles are simultaneously transformed into tetragonal BaTiO3 nanocrystals after high temperature calcination (1200 °C). The outer carbon shell of tetragonal BaTiO3 nanoparticles is removed via 500 °C calcination in air. Bi-functional ligand can modify the surface of tetragonal BaTiO3 nanoparticles. PMMA polymeric chains are growing from the initiating sites of ferroelectric BaTiO3 nanocrystal surface via the metal-free ATRP technique to obtain core/shell ferroelectric BaTiO3/PMMA hybrid nanoparticles. Changing the molar ratio between benzimidazole ring units and precursors can tune the size of ferroelectric BaTiO3 nanoparticles in the process of polycondensation, and the thickness of polymeric shell can be tailored by changing the white LED irradiation time in the organocatalyzed ATRP process. The dielectric properties of core/shell BaTiO3/PMMA hybrid nanoparticles can be also tuned by adjusting the dimension of BaTiO3 core and the molecular weight of PMMA shell.

18.
ACS Omega ; 3(2): 2463-2469, 2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-31458541

RESUMO

In this work, we have explored a simple and facile approach to prepare optically active helical polyamides. The hydroxyl groups of l-TA and d-TA were protected by O-alkoyl ester, and the resulting enantiomers, l-2,3-di-O-acetyl-tartaric acid (l-ATA) and d-2,3-di-O-acetyl-tartaric acid (d-ATA) crystals, were obtained. A pair of aliphatic homochiral polyamides of PA-l and PA-d are prepared using l-ATA, d-ATA, and achiral 1,11-undecanediamine as building blocks via interfacial polycondensation. PA-l and PA-d display negative and positive mirror circular dichroism (CD) spectra images in both solution and solid state. Moreover, the polyamides in solid state display different CD signals and stronger optical activity compared to those in ethanol and even the related chiral monomers in solid state, which was due to the helical conformation of the polyamides in solid state. Scanning electron microscopy results indicated that the aggregations of PA-l express left-handed helical sense, whereas those of PA-d express right-handed helix. In addition, the induced CD signals from the chiral conformation of the backbone become weaker when increasing the temperature from 0 to 60 °C in dilute solution. Either of the polyamides displays relatively stable CD images in solid state when elevating the temperature from 0 to 90 °C.

19.
ACS Omega ; 3(7): 8220-8225, 2018 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31458959

RESUMO

A facile fabrication strategy of transparent and upconversion photoluminescent nylon 6 (PA6) nanofiber mats was developed based on PA6 nanofiber mats, carboxylic acid-functionalized upconversion nanoparticles (UCNP-COOH), and poly(methyl methacrylate) (PMMA) solution. UCNP-COOH were prepared by a solvothermal method, followed by the ligand exchange process. The electrospinning method and the spin-coating process were employed to combine PA6 nanofiber mats with UCNP-COOH and PMMA to introduce upconversion photoluminescent properties and transparency into the nanocomposite mats, respectively. The prepared UCNP-COOH/PA6/PMMA nanofiber mats are transparent and exhibit green emission, which are similar to UCNP-COOH when they were excited under 980 nm laser. The upconversion luminescent intensity of the functional nanofiber mats can be tailored by adjusting the weight fraction of UCNP-COOH as fillers. This facile strategy can be readily used to other types of intriguing nanocomposites for diverse applications.

20.
Chem Commun (Camb) ; 53(71): 9862-9865, 2017 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-28825073

RESUMO

A one-step in situ nanoconfined pyrolysis strategy was developed to anchor highly active single Co atoms on the P,N-doped porous carbon@carbon nanotube coaxial nanocables (Co-P,N-CNT), which exhibit remarkable enhanced ORR electrocatalytic activity in both acidic and alkaline media.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...