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1.
A supramolecular polymer gel formed between triptycene-based bis(crown ether) and copolymer containing dibenzylammonium (DBA) moieties by host–guest interactions was described. We demonstrated the formation of the supramolecular polymer networks between the bis(crown ether) and the copolymer by the 1H NMR spectroscopy and solution viscometry, and we also obtained a colorless and transparent supramolecular polymer gel at high concentration. Moreover, the supramolecular polymer gel showed multi-stimuli reversible responsiveness, such as thermo-, acid/base-, and chemo- induced gel–sol transitions. Furthermore, the result of rheological measurements showed the gel has an intrinsic self-healing property, and the thixotropic process could be repeated at least three times. Interestingly, when doped with spiropyran molecules, the supramolecular polymer gel could also be employed as erasable materials. Thus, these results could be highly anticipated to benefit for further construction of smart materials with high healing efficiency, and ultimately be used in practical application.  相似文献   

2.
Summery Volume behaviors of sodium acrylate-acrylamide-N,N-methylene-bisacrylamide copolymer gels in various solvent mixtures were examined. The gel samples having the same composition but different overall concentrations exhibited a discontinuous volume change at an appropriate solvent composition when immersed in methanol-water and tetrahydrofuran-water mixtures, but at some different solvent compositions when immersed in dioxane-water and acetonitrile-water mixtures because of significant flucutuation of the gel polymer-solvent mixture interaction.  相似文献   

3.
We synthesize a non-sticky/sticky diblock copolymer, poly[styrene-b-3-(trimethoxysilyl)propylmethacrylate], to produce polymer brushes using the grafting-to technique. Uniform coatings of the polymer brushes are efficiently produced because of the multiple reactive groups offered by the sticky block, and the surface coverage and nanoscopic morphology of the brush layer are adjusted by varying the concentrations of the immersion polymer solutions and the immersion time of the substrate. The nanoscopic pattern of the polymer brushes is subsequently utilized to produce mixed polymer brushes. The resulting homo- or mixed polymer brushes change their nanoscopic morphology in response to external stimuli of temperature and solvent. The results indicate that grafting of the asymmetric non-sticky/sticky block copolymer is an efficient method for producing a surface of polymer brushes with nanoscopic chemical heterogeneity.  相似文献   

4.
Blends of two elastomeric ethylene–octene copolymers with similar octene contents having a random (ORC) and a blocky architecture (OBC) are prepared by melt mixing. The thermal and mechanical properties of ORC, OBC and their blends are investigated by DSC, dynamic mechanical analysis and tensile tests. The morphology of the semi-crystalline samples is studied by AFM and WAXS. Two types of crystals have been observed: (i) Orthorhombic crystals forming lamellae with an estimated thickness of about 13 nm composed mainly of long polyethylene-like sequences of OBC that melt a temperature of about 120 °C and (ii) fringed micellar crystals with a thickness of 2–4 nm formed basically by short polyethylene-like sequences of ORC that have melting temperatures between 30 and 80 °C. The amorphous phase contains a relatively homogeneous mixture of segments of both components indicated by the relatively uniform shape of the loss modulus peaks from dymamic-mechanical measurements for all investigated copolymers and blends. ORC crystallization is hindered in blends as indicated by lower melting enthalpies. This might be related to the high octene content of the amorphous phase at the relevant crystallization temperature as well as geometrical constraints since ORC crystallization occurs in an already semi-crystalline polymer. The results of tensile tests show that the mechanical behavior can be tailored via blend composition and morphology of the semi-crystalline material. The findings clearly indicate that blending is a powerful strategy to optimize the properties of polyolefin-based copolymers.  相似文献   

5.
A new class of organic solvent nanofiltration (OSN) membranes featuring molecular recognition sites has been fabricated by a phase inversion molecular imprinting technique. Polybenzimidazole (PBI) was employed as a functional polymer for molecular imprinting for the first time. Apart from acting as a functional polymer, PBI exhibits excellent chemical and solvent stability and can be used as a nanofiltration membrane, acting both as shape-specific adsorbent and size-exclusion membrane. The molecularly imprinted organic solvent nanofiltration (MI-OSN) membranes fabricated in this study showed both nanofiltration membrane performance, and excellent molecular recognition ability. The model system comprised roxithromycin pharmaceutical, 2-aminopyrimidine building block and N,N-dimethylaminopyridine catalyst, which are retained, adsorbed and permeated through the MI-OSN membrane, respectively. The effect of both dope solution concentration and applied pressure on the molecular recognition behaviour of MI-OSN membranes has been investigated by employing Sips and Freundlich adsorption isotherms, as well as examining the physical morphology of the membranes. The rate of adsorption was investigated, revealing that the adsorption follows second-order kinetics and is not limited by diffusion. The imprinted membrane exhibited fourfold higher flux whilst maintaining the same rejection performance in comparison to the control membrane. It is shown that increasing the transmembrane pressure across the MI-OSN membrane irreversibly suppresses the molecular recognition whilst maintaining the rejection and flux performance.  相似文献   

6.
Regular solution theory (RST) was compared with model-independent thermodynamical methods (MIM) to analyze binary mixed micelles. It was found that if the molar fractions of the surfactants obtained using RST and MIM do not differ, the binary mixed micelles are symmetrical, according to the excess Gibbs energy. The algorithm used to analyze the binary surfactant mixtures, i.e., the method for determining whether the binary mixture of the surfactants is symmetrical and obeys RST, was developed.Binary mixtures of Tween 40 – Na-3,12-dioxo-5β-cholanate (T40-3,12-DOC) and Tween 80 – Na-3,12-dioxo-5β-cholanate (T80-3,12-DOC) were analyzed. Mixed micelles of T40-3,12-DOC were found to be more stable compared with the hypothetical ideal mixed micelles, i.e., they are primarily symmetrical, according to the excess Gibbs energy, but they do not obey RST. Mixed micelles of T80-3,12-DOC were non-symmetrical, according to the excess free energy, and were less stable then the ideal mixed micelles. With the increase in the molar fraction of T80 in the mixed micelle, the micelle became less stable and decomposed into micelles that comprised the building units.  相似文献   

7.
8.
Preparation of the blend chitosan (CHI) membranes containing polyhedral oligomeric silsesquioxane (POSS) derivatives was investigated. POSS derivatives such as (3-aminopropyl)isobutyl-POSS (amino-POSS), [2-(3,4-epoxycyclohexyl)ethyl]isobutyl-POSS (epoxy-POSS), and octa(tetramethylammonium)-POSS were used. The blend CHI–amino-POSS membranes were predicted to be the most porous due to having the weakest interactions between the components in the blends. The CHI–epoxy-POSS blend membranes were assumed to be more dense owing to chemical binding of the chitosan amino groups with the epoxy groups of POSS. Studies of membrane morphology and diffusion permeability support these predictions.  相似文献   

9.
Abstract

In paper preparation and characterization of hydrogels based on chitosan of bees’ origin and modified with caffeine have been reported. Surface morphology of hydrogel materials including their average porosity has been determined. Furthermore, study of the release of caffeine from hydrogels in different environments was determined. Subsequently, studies on cytotoxicity of hydrogels to fibroblasts and cancer cells has been defined. Based on the research it can be stated that honeybees constitute an interesting material that could be a valuable source of chitosan. Prepared hydrogels had a significant negative impact on the cancer cells and did not affect negatively on fibroblasts.  相似文献   

10.
《Ceramics International》2017,43(10):7573-7580
In this study, β-TCP/CNT nanocomposite has been synthesized by solution precipitation method. Then, the effects of the different percentage of CNT (CNT1β-TCP, CNT3β-TCP, CNT5β-TCP) and surfactant (CNT1β-TCP1SDBS, CNT1β-TCP2SDBS, CNT1β-TCP3SDBS) on β-TCP/CNT nanocomposite powder were studied. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) analyses were used to characterize the samples. The observations revealed that the microstructure of 1 wt% CNT could provide dispersion without agglomeration in nanocomposite powder; however, a higher concentration of CNT powder in the nanocomposite resulted in the formation of Ca2PO7 phase. Implementing 2 wt% of SDBS as a surfactant modified the shape, size, and distribution of CNT particles on nanocomposites. Finally, the nanocomposite sample was immersed in simulated body fluid (SBF) to evaluate the in vitro bioactivity. It obviously showed an apatite layer on the surface after 7 days of immersion in SBF. Taken together, this nanocomposite might be potentially to be used as bone repair biomaterial.  相似文献   

11.
12.
Chemical product design is a multidisciplinary and diverse subject. This article provides an overview of product design while focusing on product conceptualization. Four product types are considered – molecular products, formulated products, devices and functional products. For molecular products, computer-aided design tools are used to predict the physicochemical properties of single molecules and blends. For formulated products, an integrated experiment-modeling approach is used to generate the formula with the specified product attributes. For devices and functional products, conceptual product design is carried out by modeling the product based on thermodynamics, kinetics and transport processes, by performing experiments, and by decision making based on rule-based methods The results are product specifications in terms of the type of ingredients, composition, and the structure, form, shape or configuration of the product.  相似文献   

13.
A series of polysulfone (PSF) membranes were prepared using different solvents: dimethylformamide (DMF), tetrahydrofuran, dimethylacetamide, and n-methyl-2-pyrrolidone (NMP). The PSF membrane prepared by NMP showed the highest gas permeability. The influence of propionic acid as a Lewis acid on gas separation properties of the PSF was explored. The PSF membrane prepared by the casting solution containing 25 wt% PSF, 35 wt% propionic acid, and 40 wt% NMP showed a superior gas separation performance. The gas permeation measurements indicated that incorporating 30 wt% γ-alumina nanoparticles into the PSF matrix resulted in about the respective 43% and 41% increase in CO2 and O2 permeability together with a rise in CO2/CH4 and O2/N2 selectivities (13% and 7%, respectively). Furthermore, by rearranged modified Maxwell model, the role and nature of the interfacial layer in the PSF-based mixed matrix membranes were mathematically analyzed considering a reduced permeability factor.  相似文献   

14.
This paper describes the influence of particle size distribution (PSD) of refractory silica on the suspension viscosity, packing density, and segregation in layers solidified by ceramic stereolithography (CerSLA). Using bimodal PSD displays most significant decrease of suspension viscosity than suspension made of mono-modal PSD. Given the Krieger-Dougherty model and packing density experiment, the lower viscosity results from the higher maximum volume fraction, φm, reached through the closely packed particles. Furthermore, from the differential sedimentation of coarser or denser particles in suspensions, particle size segregation in layers is detected. To determine the distribution of particle size within each layer, a linear intercept method is used, which demonstrates the vertical changes in PSD. Mono–modal PSD case show severe segregations in solidified layers in which the population of larger or denser particles is greater near the bottom. However, much less segregation occurs with bimodal PSD due to suppressed segregation.  相似文献   

15.
Oxynitrides of early transition metals are bifunctional catalysts active in hydrodenitrogenation (HDN). The strength of the hydrogenating function and the acidic properties of molybdenum and niobium oxynitrides were investigated, as well as the inhibiting effect of ammonia and the effect of solvent (cyclohexane or tetradecane) on HDN of 1,2,3,4‐tetrahydroquinoline (1–4 THQ). Even under high hydrogen pressure (4.5 MPa) the reaction was found to be able to proceed without hydrogenation of the aromatic cycle of 1–4 THQ before C–N bond scission, which is not the case over sulfided NiMo supported catalysts in HDN. Experiments in presence of ammonia permitted to support a bifunctional dual site concept. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Polycondensation of o-cresol (OC) with furfural (F) was carried out under various reaction conditions. The resultant resin samples designated as OCFs were characterized by elemental analysis, spectral studies, viscometric measurement of solution in 1,4-dioxane and by the estimation of the number – average molecular weight. Thermogravimetric analysis (TGA) of selected resin samples has been carried out. The curing kinetic reaction of selected OCF resin samples was studied by differential scanning calorimetry (DSC). Hexamethylenetetramine (Hexamine) has been used as curing reagent.  相似文献   

17.
Interfacial, thermodynamic, and performance properties of aqueous binary mixtures of α-sulfonato palmitic acid methyl ester, C14H29CH(SO3Na)COOCH3(PES), and hexaoxyethylene monododecyl ether, CH3(CH2)11(OCH2CH2)6OH (C12E6), were investigated with tensiometric, conductometric, fluorimetric, and viscometric techniques. The critical micelle concentration (CMC), maximum surface excess, minimum area per molecule of surfactant at the air/water interface, and the thermodynamics of micellization and adsorption were determined. The CMC was very low for mixed systems, indicating probable use as a detergent with less effect on the environment because of surfactant biodegradability and less amount in the environment. The interaction parameter βm, computed by using the theory of Rubingh and Maeda, indicated an attractive interaction (synergism) between the surfactant molecules, which was also confirmed by proton nuclear magnetic resonance studies in the mixed micelle. The micellar aggregation number (N agg), determined by using a steady-state fluorescence quenching method at a total surfactant concentration of about ∼10 mM at 25°C, was almost independent of the surfactant mixture composition. The micropolarity and the binding constant (K sv) for the C12E6/PES mixed system were determined by the ratio of the intensities (I 1/I 3) of the pyrene fluorescence emission spectrum, and the local microenvironment inside the micelle was found to be polar. The viscosity of the mixed system at all mole fractions suggested that mixed micelles are nonspherical in nature. The cloud point of oxyethylene group-containing surfactants was increased by the addition of PES. Foaming was temperature dependent, and a 1∶1 mixed system showed minimum foaming. All performance properties were composition dependent.  相似文献   

18.
Silibinin-loaded soy flour–zinc oxide nanoparticle (ZnO) nanoparticles were prepared and characterized by different techniques. The average particle size and zeta potential value of the nanoparticles were found in the range 10–15?nm and ?29.88 to ?40.85?mV, respectively. The effects of ZnO nanoparticle, surfactant, and cross-linker were evaluated with regard to swelling, encapsulation efficiency, and drug release in different pH medium. Both swelling degree (%) and cumulative release (%) were better in pH 7.4 and maximum cumulative release (%) was 50%. Cytotoxicity study was performed by MTT assay using normal human blood and MDA-MB-435S cancer cell lines.  相似文献   

19.
Static mixers and multifunctional heat exchangers/reactors (MHE/R) are qualified as efficient receptacles for processes including physical or chemical transformations accompanied by heat transfer due to their high productivity and reduced energy expenditures. The present work reviews recent conceptual and technological innovations in passive static mixers and continuous in-line reactors. Current industrial applications are discussed from a process intensification perspective, focusing on mixing and mass transfer performance. Typical experimental techniques employed to characterize and quantify the mixing process are explored. The work is complemented by a review of mixing fundamentals, knowledge of which allows the development of theoretical models crucial for the analysis of experimental data, like the chemical probe mixing assessment method. Considering the development of continuous flow equipment in numerous processes, advances in this field will certainly be of increasing interest to the scientific and industrial communities.  相似文献   

20.
Poly(N-isopropylacrylamide) (PNIPAM) hydrogels were simply prepared by free radical polymerization in different methanol–water mixture. A scanning electron microscopy study revealed that the freeze-dried hydrogels were macroporous. The swelling ratios in water at 20°C of the resulting hydrogels followed the order: X0.43>X0.21>X0.76 ≈ X0.57>X0.31>X0.13>X0.06>X0, where Xm denotes a gel prepared in a methanol–water mixture with m mole fraction of methanol (xm). Below the lower critical solution temperature, the swelling ratio values of all of the hydrogels gradually decreased with the increase in the temperature. The complete collapse of the PNIPAM chain of all the gels occurred at about 38°C, whereas the same was observed at about 35°C for the conventional gel prepared in water. The swelling ratio values of all the PNIPAM gels in the methanol–water mixtures with different xm values at 20°C passed through a minimum in the cononsolvency zone. The deswelling rates of the hydrogels decreased in the following order: X0.43> X0.31> X0.21> X0.57> X0.76 ≈ X0.13> X0.06> X0. The reswelling rates of these hydrogels decreased in the following order: X0> X0.31> X0.06 ≈ X0.13 > X0.76> X0.57> X0.21> X0.43. The release rates of the Tramadol Hydrochloride drug at 37°C from the drug-loaded hydrogels were almost same for all of the hydrogels. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

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