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1.
Langmuir ; 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32027137

RESUMO

Silicone surfactants consist of siloxane or carbosilane hydrophobic groups that permite better surface activity compared with alkane surfactants. The surfactants containing Si atom which brings good bond flexibility and low cohesive energy properties are a promising class of materials for special surface working, but few studies address the molecular architecture surface activity mechanisim(s) of these surfactants. To determine different Si bond works on the surface tension, aggregation behavior, and hydrolysis rate, two novel carboxylate surfactants with different silicone hydrophobic groups (Si-O-Si, and Si-C-Si) were synthesized and systematic investigated on the surface activities, aggregates behavior, and solution stabilities. Both surfactants have excellent surface activities that we attribute to the siliconed hydrophobic structure. The hydrolysis resistance of carbosilane based carboxylate surfactant was better than that of siloxane based carboxylate surfactant. The differences of hydrolysis processes for the surfactants were confirmed by mass spectrum and kinetic analysis. Meanwhile, the aggregation number of Si-C-Si surfactant was determined by the fluorescence quenching method for first time.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32048514

RESUMO

Developing a chemosensor for rapid, sensitive and visual detection of iodide (I-) by a simple synthetic strategy is still a challenge. Herein, we report a novel highly efficient iodide sensor by simply introducing ionic imidazolium groups into the porous network. This sensor, i.e., a fluorescent ionic porous framework (IPF), was prepared by the quaternization reaction of octa((benzylchloride)ethenyl)silsesquioxane and 1,4-bis(1H-imidazol-1-yl)benzene and exhibits moderate porosity with the Brunauer-Emmett-Teller surface area of 379 m2 g-1 and blue fluorescence when excited by UV light. The IPF suspension in water can detect I- with high sensitivity and selectivity among various anions and quick response by fluorescence quenching. In contrast to no response towards I- by the linear model compound and the enhanced sensing performance with an increment of porosity, this finding indicates the porosity of IPF is important for the detection of I- and an inducement of the sensing process. A fluorescent paper sensor was further developed and likewise shows high efficiency for the visual detection of I-, suggesting its potential in convenient and on-site sensing of I-. In addition, the paper sensor is recyclable with remarkable fluorescence resuming ratio of 83% after ten times cycle detection. Moreover, the developed sensor is used for the analysis of real samples. This work represents the first example of the detection of I- by an ionic porous polymer. Compared with conventional iodide sensors, the present sensor does not require unique structures to form the pesudocavity during sensing I- and can easily achieve high efficiency by incorporating ionic hydrogen bond donors into the porous network, indicating the importance of porosity and the feasibility of replacing the pesudocavity by a real cavity (or pore). More iodide sensors with high efficiency can be designed and fabricated by this novel and simple strategy.

3.
Dalton Trans ; 49(6): 1883-1890, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31967139

RESUMO

A tetrapyridine-decorated tetraphenylethene (TPE) ligand 1 was designed, which, upon interacting with silver ions, displayed "turn-on" fluorescence in a dilute solution. The fluorescence enhancement can be attributed to the cooperative effect of restriction of the intramolecular rotation by metal coordination and silver ion induced aggregation. Furthermore, the fluorescence turn-on performance of AIE molecules in a dilute solution leads to tunable fluorescence properties including white-light emission by simply mixing AIE and ACQ molecules together, which might bridge the gap between the AIE and ACQ phenomena for the construction of color-tunable fluorescence systems.

4.
Macromol Rapid Commun ; 40(23): e1900469, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31804763

RESUMO

Wearable devices have gained substantial interest for a wide range of applications, including biomonitoring and entertainment. They are basically composed of sensors and substrate materials. Recently, silicone materials have been extensively used in wearable devices because of their unique properties. Silicone materials, which possess remarkable insulation, predominantly serve as a substrate instead of a signaling material due to the indispensable electrical conductivity in wearable devices. Herein, a novel kind of silicone material, with both good conductivity and excellent self-healing efficiency, is designed by introducing imidazolium into the silicone polymer in one step. The free ions afford an ionic conductivity as high as 2.79 × 10-4 S m-1 , representing a significant improvement over traditional silicone materials. Because of the good conductivity, the silicone material is sensitive to stretching and can be applied as a flexible sensor. On the other hand, the material exhibits a high healing efficiency, reaching 89% in 6 h, due to the dynamic supramolecular interaction of the ion crosslink sites at the crack surface. Furthermore, the silicone material emits a yellow-green fluorescence under UV light.

5.
Langmuir ; 35(30): 9785-9793, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31280568

RESUMO

A series of sulfonate-based silicone surfactants with different hydrophobic groups were synthesized. Two synthetic strategies are introduced to permit exquisite control over the hydrophobic moieties. Solution behavior of these surfactants was investigated by surface tensiometry, electrical conductivity, transmission electron microscopy, and dynamic light scattering. The results indicate that the aqueous behavior of the surfactants was distinctly influenced by the hydrophobic groups. Subtle distinctions in surfactant-related properties, which can be attributed to the three-dimensional molecular structures of the surfactants, can be seen for compounds with different hydrophobic moieties. Contact angle results of these surfactants indicate that they have super dispersal ability with the potential value in agriculture.

6.
Langmuir ; 34(14): 4382-4389, 2018 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-29565594

RESUMO

Three silicone surfactants, 3-tris(trimethylsiloxy)silylpropyl sulfonate with different alkaline counterions (lithium, sodium, and potassium), were synthesized for the first time. Their chemical structures were confirmed by FT-IR spectra, 1H NMR, and ESI-MS, and their behaviors in aqueous solutions were investigated by surface tensiometry, electrical conductivity, dynamic light scattering, and different transmission electron microscopy techniques. These anionic silicone surfactants exhibited remarkable surface activity and could reduce the surface tension of water to as low as 19.8 mN/m at the critical aggregate concentration (CAC). The adsorption and aggregation behaviors of these surfactants were assessed by determining the adsorption efficiency, minimum average area per surfactant molecule, and thermodynamic parameters. The cryo-TEM results verified that these molecules could form vesicles in water above the CAC. Moreover, the lowest surface tension, the smallest CAC value, and the largest aggregate size have been reached with potassium counterions. Thus, the different behavior of these surfactants in water can be explained by the different sizes of the hydrated ions.

7.
Spectrochim Acta A Mol Biomol Spectrosc ; 188: 202-207, 2018 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-28715687

RESUMO

In this study, thiophene was linked to polybenzene to generate novel fluorescent probes, namely 3,4-diphenyl-2,5-di(2-thienyl)phenyl-trimethylsilane (DPTB-TMS) with a -SiMe3 substituent and 3,4-diphenyl-2,5-di(2-thienyl)phenyl (DPTB) without the -SiMe3 substituent, respectively. Both of the two compounds exhibit aggregation-enhanced emission (AEE) properties in tetrahydrofuran/water mixtures due to restricted intramolecular rotation of the peripheral groups, which make the two compounds good candidates for the detection of Fe3+ ions in aqueous-based solutions. The fluorescence intensity of the two compounds decreases immediately and obviously upon addition of a trace amount of Fe3+, and decreases continuously as the amount of Fe3+ increases. The fluorescence was quenched to 92% of its initial intensity when the amount of Fe3+ ions reached 6µmol for DPTB-TMS and to 80% for DPTB in the systems, indicating that the compound with the -SiMe3 group is a more effective probe. The detection limit was found to be 1.17µM (65ppb). The detection mechanism is proposed to be static quenching. DPTB-TMS is highly efficient for the detection of ferric ions even in the presence of other metal ions. In addition, the method is also successfully applied to the detection of ferric ions in water, blood serum, or solid films. This indicates that these polybenzene compounds can be applied as low-cost, high selectivity, and high efficiency Fe3+ probes in water or in clinical applications.

8.
Polymers (Basel) ; 10(8)2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30960842

RESUMO

In this paper, two different models of hybrid ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSSs) have been prepared. Additionally, these ILs based on POSSs (ILs-POSSs) exhibited excellent thermal stabilities and low glass transition temperatures. ¹H, 13C, and 29Si nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to confirm the structures of the IL-POSSs. Furthermore, the spherical vesicle structures of two IL-POSSs were observed and were caused by self-assembly behaviors. In addition, we found it very meaningful that these two ILs showed lower detection limits of 2.57 × 10-6 and 3.98 × 10-6 mol/L for detecting picric acid (PA). Moreover, the experimental data revealed that the products have high sensitivity for detecting a series of nitroaromatic compounds-including 4-nitrophenol, 2,4-dinitrophenol, and PA-and relatively comprehensive explosive detection in all of the tests of IL-POSSs with nitroaromatic compounds thus far. Additionally, the data indicate that these two new ILs have great potential for the detection of explosives. Therefore, our work may provide new materials including ILs as fluorescent sensors in detecting nitroaromatic explosives.

9.
Phys Chem Chem Phys ; 19(46): 31011-31023, 2017 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-28967926

RESUMO

Different from the self-assembly of neutral polymers, polyelectrolytes self-assemble into smaller aggregates with a more loosely assembled structure, which results from the repulsive forces acting between similar electrical compositions with the introduction of ions. The Y-shaped weak polyelectrolytes self-assemble into a core-shell type cylindrical structure with a hexagonal arrangement in a thin film, whose thickness is smaller than the gyration radius of the polymer chain. The corresponding formation mechanism consists of enrichment of the same components, adjustment of the shape of the aggregate, and the subsequent separation into individual aggregates. With the increase in the thickness of the thin film until it exceeds the gyration radius of the polymer chain, combined with the greater freedom of movement along the direction of thin film thickness, the self-assembled structure changes into a micellar structure. Under confinement, the repulsive force to the polymeric components is weakened by the repulsive forces among polyelectrolyte components with like charges, and this helps in generating aggregates with more uniform size and density distribution. In particular, when the repulsive force between the walls and the core forming components is greater than that between the walls and the shell forming components, such asymmetric confinement produces a crossed-cylindrical structure with nearly perpendicular arrangement of two cylinder arrays. Similarly, a novel three-crossed cylinder morphology is self-assembled upon removal of confinement.

10.
Sci Rep ; 7(1): 13610, 2017 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-29051545

RESUMO

The self-assembly of a reformed symmetric H-shaped copolymer with four hydrophilic branches and one hydrophobic stem was systematically investigated. The existence of vacancies is vital to regulate the sizes of self-assembled cylinders to be able to form a hexagonal arrangement. With the introduction of horizontal-orientated confinement, a micellar structure is formed through a coalescence mechanism. The short acting distance and large influencing area of the confinement produces numerous small-sized micelles. Additionally, the cycled "contraction-expansion" change helps achieve hexagonal arrangement. In contrast, the introduction of lateral-oriented confinement with long acting distance and small influencing area cannot change the cylindrical structure. Under the fission mechanism, in which the larger cylinder splits into smaller ones, it is quite efficient to generate hierarchical-sized cylinders from larger-sized cylinders in the middle region and smaller-sized cylinders near both walls. The results indicate the possibility of regulating the characteristics of a nanomaterial by tuning the molecular structure of the copolymer and the parameters of the introduced confinement, which are closely related to the self-assembly structure.

11.
Phys Chem Chem Phys ; 19(33): 21938-21945, 2017 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-28612874

RESUMO

The self-assembly of a copolymer thin film, whose molecular structure is composed of one hydrophobic branch and two hydrophilic branches, gives a cylindrical structure consisting of a hydrophobic core and a hydrophilic outer surface. The confinement-induced loss of entropy leads the copolymer to self-assemble into a hexagonal arrangement of cylindrical structures. This hexagonal arrangement is of two induced self-assembly structures under one-dimensional confinement in thin films, i.e., micellar structures with uniform density of an individual core, as well as lamellar structures with two separated hydrophobic layers and one hydrophilic layer. When the repulsive force of the confinement is greater for the hydrophobic polymeric component than for the hydrophilic polymeric component, the self-assembled density of the cores is broad. A proportional change in the individual volume suggests interactions between the walls and the hydrophobic core, which plays a vital role in the formation of the self-assembled structure. A basic understanding of the one-dimensional confinement investigated in this study serves to elucidate the more complex two- and three-dimensional confinements and provides further insights for the design of nanomaterials with novel morphologies.

12.
Chem Asian J ; 12(11): 1213-1217, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28371412

RESUMO

Nonconventional organic luminogens have attracted a great deal of interests owing to their intriguing properties (e.g., unusual fluorescence emission) and promising applications. According to previous studies, it was found that introduction of Si-O could enhance the fluorescence emission of the luminogens. Herein, we have synthesized some fluorescent siloxane derivatives and similar molecules without Si-O units by simple and efficient modification to investigate the role of Si-O units in the emission. It was found that the strong emission could be observed in dilute solutions of siloxane derivatives, but not in the carbon compounds. UV/Vis absorption, fluorescence spectra, nuclear magnetic resonance spectra, and theoretical calculations indicated that the heteroatom and the Si-O unit formed the coordination bond in the siloxane derivatives, resulting in enhanced fluorescence emission.

14.
Nanoscale ; 9(5): 1909-1915, 2017 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-28094404

RESUMO

Carbon dots (CDs) usually emit a strong blue light and excitation wavelength dependent long wavelength lights. This significantly limits their applications because one has to use a series of different excitation light sources to get different colors and the long wavelength emissions are usually very weak. We found that one type of CDs synthesized from p-phenylenediamine could emit various long wavelength lights (green to red) independent of the excitation wavelength when dispersed in different solvents. The photoluminescence quantum yields of the same CDs were 10-35% in different solvents for different color emissions. Based on this solvent-color effect, we further mixed the same CDs with different polymers to form solid CD films for various color emissions, and these film emissions were also excitation wavelength independent. Multicolor LEDs were demonstrated with the same CDs in solution and solid film states for color displays.

16.
Chemistry ; 22(40): 14319-27, 2016 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-27533795

RESUMO

Two series of new polyhedral oligomeric silsesquioxane (POSS)-based fluorescent hybrid porous polymers, HPP-1 and HPP-2, have been prepared by the Heck reaction of octavinylsilsesquioxane with 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and 1,3,6,8-tetrabromopyrene, respectively. Three sets of reaction conditions were employed to assess their effect on fluorescence. These materials exhibit tunable fluorescence from nearly no fluorescence to bright fluorescence both in the solid state and dispersed in ethanol under UV light irradiation by simply altering the reaction conditions. We speculated that the difference may be attributable to the fluorescence quenching induced by Et3 N, P(o-CH3 Ph)3 , and their hydrogen bromide salts employed in the reactions. This finding could give valuable suggestions for the construction of porous polymers with tunable/controllable fluorescence, especially those prepared by Heck and Sonogashira reactions in which these quenchers are used as organic bases or co-catalysts. In addition, the porosities can also be tuned, but different trends in porosity have been found in these two series of polymers, which suggests that various factors should be carefully considered in the preparation of porous polymers with tunable/controllable porosity. Furthermore, HPP-1 c showed moderate CO2 uptake and fluorescence that was efficiently quenched by nitroaromatic explosives, thereby indicating that these materials could be utilized as solid absorbents for the capture and storage of CO2 and as sensing agents for the detection of explosives.

17.
Macromol Rapid Commun ; 37(13): 1052-9, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27159536

RESUMO

Cross-linked silicone elastomers constructed with dynamic-covalent boronic esters are first synthesized by photoinitiated radical thiol-ene "click" chemistry. The resultant samples can be cut with a sharp knife into two pieces and then healed via the reversibility of the boronic ester cross-linkages to restore the original silicone sample within 30 min. Regulation of luminescent properties is achieved by incorporating organic dye into the elastomers through a "one-pot" thiol-ene reaction. The proposed synthesis procedure demonstrates a new strategy to produce boronic acid silicone materials capable of self-healing without external forces.


Assuntos
Ácidos Borônicos/química , Química Click , Elastômeros/química , Ésteres/química , Siloxanas/química , Compostos de Sulfidrila/química , Estrutura Molecular
18.
Macromol Rapid Commun ; 37(7): 597-604, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26847367

RESUMO

A series of high-efficiency, full-color fluorescent elastomers based on polysiloxane matrix prepared by an easy thiol-ene "click" reaction is reported here. It is found for the first time that the same elastomer can emit transformable colors by conveniently altering the excitation wavelength because of the effect of energy transfer and the "fluorescence switch" of lanthanide ions. A fluent change in emission colors can also be feasible and conveniently reproducible by varying the stoichiometric ratio of lanthanide ions and rhodamine-B in solution and in polymer elastomers. The obtained elastomers are further coated onto commercially available UV-LED cells from the solution medium followed by an in situ cross-linking step.


Assuntos
Elastômeros de Silicone/química , Compostos de Sulfidrila/química , Raios Ultravioleta , Química Click , Corantes Fluorescentes/química , Elementos da Série dos Lantanídeos/química , Rodaminas/química , Siloxanas/química , Espectrometria de Fluorescência
19.
Chemistry ; 22(14): 5010-6, 2016 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-26916362

RESUMO

N-Methylaniline-induced Si-Si bond cleavage of Si2Cl6 has been theoretically studied. All calculations were performed by using DFT at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) levels. An ionic SN i-Si nucleophilic substitution mechanism, which is a newly found nucleophilic substitution in silicon-containing compounds, is proposed in the N-methylaniline-induced Si-Si bond cleavage in Si2Cl6. Unlike general S(N)i-Si nucleophilic substitutions that go through a pentacoordinated silicon transition state, ionic nucleophilic substitution goes through a tetracoordinated silicon transition state, in which the Si-Si bond is broken and siliconium ions are formed. Special cleavage of the Si-Si bond is presumably due to the good bonding strength between Si and N atoms, which leads to polarization of the Si-Si bond and eventually to heterolytic cleavage. Calculation results show that, in excess N-methylaniline, the final products of the reaction, including (NMePh)(3-n) SiHCl(n) (n=0-2) and (NMePh)(4-n) SiCl(n) (n=2-3), are the Si-Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic S(N)i-Si nucleophilic substitution mechanism can also be employed to describe the amination of chlorosilane by N-methylaniline. The suggested mechanisms are consistent with experimental data.

20.
Macromol Rapid Commun ; 37(4): 318-22, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26676283

RESUMO

A combination of a thiol-Michael addition reaction and a free radical mediated thiol-ene reaction is employed as a facile and efficient approach to carbosiloxane dendrimer synthesis. For the first time, carbosiloxane dendrimers are constructed rapidly by an orthogonal click strategy without protection/deprotection procedures. The chemoselectivity of these two thiol-ene click reactions leads to a design of a new monomer containing both electron-deficient carbon-carbon double bonds and unconjugated carbon-carbon double bonds. Siloxane bonds are introduced as the linker between these two kinds of carbon-carbon double bonds. Starting from a bifunctional thiol core, the dendrimers are constructed by iterative thiol-ene click reactions under different but both mild reaction conditions. After simple purification steps the fifth dendrimer with 54 peripheral functional groups is obtained with an excellent overall yield in a single day. Furthermore, a strong blue glow is observed when the dendrimer is excited by a UV lamp.


Assuntos
Dendrímeros/síntese química , Siloxanas/química , Compostos de Sulfidrila/química , Química Click , Dendrímeros/química , Estrutura Molecular
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