Design of all-optical tunable filter based on two-dimensional photonic crystals for WDM (wave division multiplexing) applications

In this paper, all-optical tunable filters based on two-dimensional photonic crystals with very small dimensions for optical telecommunication of WDM technology are designed and simulated. The structure is made of air holes in a dielectric background. The tuning is done by changing resonant defect angle. The channels obtained for this structure will be set in wavelength range of 1550 nm. Created channels are at wavelengths of 1550, 1551, 1552, and 1565 (16 channels); the distance between adjacent channels is 1 nm. Design and simulation of this filter is done by RSOFT software. Quality factor, transmission efficiency, and band gap shows that filter performance is very good.     

Superior toughness obtained via tuning the compatibility of poly(ethylene terephthalate)/poly(ethylene–octene) blends

As a partial of the systematic investigation of the preparation and characterization of poly(ethylene terephthalate) (PET) blending/compounding materials with excellent comprehensive mechanics in the authors’ group, this study deals with the compatibilization modification of PET/elastomer blends to obtain superior toughness. Poly(ethylene–octene) (POE) was employed as elastomer toughener, while maleic anhydride grafted POE (mPOE) was selected as compatibilizer. To highlight the effect of compatibility on toughening, the sum amount of elastomer component, POE and mPOE, was fixed at 20 wt%, but the mass ratio of mPOE/POE was changeable. It is interesting to find that an optimization of toughening can be attained at 3 wt% mPOE, at which the notched impact strength is about 15 folds for that of neat PET. The toughening behavior observed is due to a combination of good dispersion of elastomer phase particles and, particularly, appropriate interfacial adhesion condition. Microscopic fractured morphology reveals that a moderate level of interfacial adhesion is important for good dispersion of elastomer phase and debonding between PET matrix and elastomer particles, which initiate matrix shear yielding to dissipate more energy than other interfacial adhesion conditions.     

Structural and optical properties of both pure poly(3-octylthiophene) (P3OT) and P3OT/fullerene films

We have investigated the structural and optical properties of P3OT and P3OT/fullerene thin films in view of their application as active layer in plastic solar cells. Films of these materials were prepared by spin coating from toluene solutions onto silicon substrates. Their optical properties were studied by spectroscopic ellipsometry, which provides the anisotropic dielectric function of the films. Moreover, structural properties were studied using X-ray diffraction. A close correlation between the results obtained by both methods could be found. Especially, the strong optical anisotropy of the films can be explained in terms of a preferable orientation of the polymer chains parallel to the substrate. The effect of the optical anisotropy on the performance of optoelectronic devices is discussed.     

Preparation of P(St-NMA) microsphere inks and their application in photonic crystal patterns with brilliant structural colors

Patterned photonic crystals with structural colors on textile substrates have attracted a special attention due to the great advantages in application, which currently become a research hot-spot. This study utilized an ink-jet printing technology to prepare high-quality photonic crystal patterns with structural colors on polyester substrates. The self-assembly temperature of poly(styrene-N-methylol acrylamide) (P(St-NMA)) microspheres set to construct photonic crystals were deeply optimized. Moreover, the structural colors of prepared photonic crystal patterns were characterized and evaluated. When the mass fraction of P(St-NMA) microspheres was 1.0 wt.%, the pH value ranged from 5 to 7, and the surface tension was in the range of 63.79 to 71.20 mN/m, inks could present the best print performance. At 60 °C, prepared P(St-NMA) microsphere inks were good for printing to obtain patterned photonic crystals with regular arrangement and beautiful structural colors. Specifically, photonic crystals with different colors could be constructed by regulating the diameter of microspheres in inks, and prepared structural colors exhibited distinct iridescent phenomenon. The present results could provide a theoretical basis for the industrial realization of patterned photonic crystals by ink-jet printing technology.     

Synthesis and characterization of conjugated poly (amino benzyl alcohol) and poly (ethylene glycol) for solid polymer electrolyte

A solid polymer electrolyte chemically bonded to a π-conjugated polymer was prepared for the use as a designed ladder-type structure by the graft copolymerization of poly (aminobenzyl alcohol) (PABA) with poly (ethylene glycol) (PEG). PABA was used as the frame for the ladder and the PEG as the rungs. The expected synergic effect afforded by the introduction of the ionic salts into the crosslinked conjugated polymer and PEG network was investigated as a function of its structure, morphology, and ionic conductivity. The insertion of the ionic salts into the PABA-PEG-PABA network led to the enhancement of the ionic conductivity compared to that of PEG/LiClO₄. The synergic effect may be explained by the more efficient segmental motion of the polymer chains or better ion mobility in the network due to the interrupted crystallization of the PEG chains. The fine tuning of the crosslinked conjugated polymer gel might enable it to show a faster response to electrochemical stimuli.     

聚(乳酸-氨基酸)共聚物的合成及性能研究进展

本文详细介绍了聚(乳酸-氨基酸)线型无规共聚物、线型交替共聚物、嵌段共聚物、接枝共聚物、交联共聚物的合成路线及其性能的研究进展.在聚乳酸(PLA)大分子链中引入氨基酸(包括赖氨酸、天冬氨酸、丝氨酸、半胱氨酸等)链段后,可获得含有氨基、羧基、羟基、巯基等反应活性基团的聚(乳酸-氨基酸)共聚物.此类共聚物在保持聚乳酸良好生物相容性的基础上,还具有反应活性功能性、亲水亲脂两亲性、降解速度可控性.     

Multipass membrane air-stripping (MAS) for removing volatile organic compounds (VOCs) from surfactant micellar solutions

Air-stripping is one of the most effective technologies for removing volatile organic compounds (VOCs) from surfactant solutions, although the presence of surfactant poses some unique challenges. This study evaluated the effect of a mixed surfactant system on the apparent Henry's law constant of tetrachloroethylene (PCE) and the efficiency of PCE removal from surfactant solutions using a lab-scale hollow fiber membrane contactor. Results show that the presence of surfactant significantly reduced the apparent Henry's law constant of PCE, and the reduction was proportional to the total surfactant concentration. PCE removal efficiency by membrane air-stripping (MAS) decreased as the surfactant system transitioned from solubilization to supersolubilization. Besides significantly reducing the apparent volatility of VOCs, the presence of surfactant brings additional mass transfer resistance in air-stripping, which makes it difficult to achieve high levels of contaminant removal, even at very high air/liquid (A/L) ratios. In contrast, multipass/multistage MAS operated at low A/L ratios could achieve near 100% contaminant removal because of less mass transfer limitation during each stripping pass/stage. Experimental results, together with model calculations demonstrate multipass (and multistage) air-stripping as a cost-effective alternative for removing VOCs from surfactant micellar solutions compared to the options of using large air strippers or operating at high A/L ratios.     

iCVD growth of poly(N-vinylimidazole) and poly(N-vinylimidazole-co-N-vinylpyrrolidone)

The imidazole group plays an important role in α-chymotrypsin catalysis, metal-ion complexation, counterion or dye binding. Poly(N-vinylimidazole), PVI, is also a good model polymer interacting with neutral salts. The poly(N-vinylimidazole-co-N-vinylpyrrolidone) copolymer P(VI-co-VP), can be used to produce highly functionalized polymers.PVI and P(VI-co-VP) thins films were achieved via initiated chemical vapor deposition (iCVD), a solvent-free process to form films under mild conditions. The polymerization was initiated by hot wire heated tert-butyl peroxide (TBPO). The chemical structure and compositions of the polymers were analyzed using FTIR and XPS. The growth rate of PVI as a function of the pressure inside the iCVD reactor was measured to be 1 nm/h mTorr. The XPS results show that the functional groups were retained in the polymer deposited. For the P(VI-co-VP) deposition, there are more VI groups found in the co-polymer chain even when the reacting monomers were fed in the same ratio.     

Synthesis,characterization and kinetic of a surfactant-modified bentonite used to remove As(III) and As(V) from aqueous solution

In this study, organobentonites were prepared by modification of bentonite with various cationic surfactants, and were used to remove As(V) and As(III) from aqueous solution. The results showed that the adsorption capacities of bentonite modified with octadecyl benzyl dimethyl ammonium (SMB3) were 0.288 mg/g for As(V) and 0.102 mg/g for As(III), which were much higher compared to 0.043 and 0.036 mg/g of un-modified bentonite (UB). The adsorption kinetics were fitted well with the pseudo-second-order model with rate constants of 46.7 × 10⁻³ g/mg h for As(V) and 3.1 × 10⁻³ g/mg h for As(III), respectively. The maximum adsorption capacity of As(V) derived from the Langmuir equation reached as high as 1.48 mg/g, while the maximum adsorption capacity of As(III) was 0.82 mg/g. The adsorption of As(V) and As(III) was strongly dependent on solution pH. Addition of anions did not impact on As(III) adsorption, while they clearly suppressed adsorption of As(V). In addition, this study also showed that desorbed rates were 74.61% for As(V) and 30.32% for As(III), respectively, after regeneration of SMB3 in 0.1 M HCl solution. Furthermore, in order to interpret the proposed absorption mechanism, both SMB3 and UB were extensively characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses.     

Fabrication and characterization of chemical sensors made from nanostructured films of poly(o-ethoxyaniline) prepared with different doping acids

Chemical sensors made from nanostructured films of poly(o-ethoxyaniline) POEA and poly(sodium 4-styrene sulfonate) PSS are produced and used to detect and distinguish 4 chemicals in solution at 20 mM, including sucrose, NaCl, HCl, and caffeine. These substances are used in order to mimic the 4 basic tastes recognized by humans, namely sweet, salty, sour, and bitter, respectively. The sensors are produced by the deposition of POEA/PSS films at the top of interdigitated microelectrodes via the layer-by-layer technique, using POEA solutions containing different dopant acids. Besides the different characteristics of the POEA/PSS films investigated by UV-Vis and Raman spectroscopies, and by atomic force microscopy, it is observed that their electrical response to the different chemicals in liquid media is very fast, in the order of seconds, systematical, reproducible, and extremely dependent on the type of acid used for film fabrication. The responses of the as-prepared sensors are reproducible and repetitive after many cycles of operation. Furthermore, the use of an “electronic tongue” composed by an array of these sensors and principal component analysis as pattern recognition tool allows one to reasonably distinguish test solutions according to their chemical composition.     

Additive manufacturing of mechanical testing samples based on virgin poly (lactic acid) (PLA) and PLA/wood fibre composites

3D printing in additive manufacturing is considered as one of key technologies to the future high-precision manufacturing in order to benefit diverse industries in building construction, product development, biomedical innovation, etc. The increasing applications of 3D printed components depend primarily on their significant merits of reduced weight, minimum used materials, high precision and shorter production time. Furthermore, it is very crucial that such 3D printed components can maintain the same or even better material performance and product quality as those achieved by conventional manufacturing methods. This study successfully fabricated 3D printed mechanical testing samples of PLA and PLA/wood fibre composites. 3D printing parameters including infill density, layer height and the number of shells were investigated via design of experiments (DoE), among which the number of shells was determined as the most significant factor for maximising tensile strengths of PLA samples. Further, DoE work evaluated the effect of material type (i.e., neat PLA and PLA/wood fibres) and the number of shells on tensile, flexural and impact strengths of material samples. It is suggested that material type is the only predominant factor for maximising all mechanical strengths, which however are consistently lower for PLA/wood fibre composites when compared with those of neat PLA. Increasing the number of shells, on the other hand, has been found to improve almost all strength levels and decrease infill cavities. The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0211-3     

生物活性聚乙烯醇/羟基磷灰石复合水凝胶的结构与性能

本工作研究了聚乙烯醇和羟基磷灰石复合型生物活性水凝胶,探讨了工艺条件和配方对其拉伸强度,压缩强度,粘弹性、润滑性等生物力学性能的影响,观察和比较了复合水凝胶的微观形貌.研究表明聚乙烯醇和羟基磷灰石可形成接近纳米级的均匀分散结构,良好相容,使复合凝胶的力学强度和润滑性能提高,其应力松弛性能更接近天然软骨的粘弹性.     

Microdisk laser emission and electrical properties of composite films based on poly(3-hexylthiophene)s with different stereoregularity

The optical and electrical properties of composite thin films of poly(3-hexylthiophene)s (PAT6s), processing different stereo-regularity originating from side-chain regio orders have been studied. The laser emission properties of PAT6 composite thin films in microdisk structure have been observed by pulsed photopumping. From the electrical and optical measurements, the electrical conductivity and the quantum efficiency of the PAT6 composite films were estimated. The emission and conductivity depending on the mixture ratios were discussed by taking the stereo-regularity of the molecular structure into consideration.     

A novel strategy for improving upconversion luminescence of NaYF4：Yb, Er nanocrystals by coupling with hybrids of silver plasmon nanostructures and poly（methyl methacrylate） photonic crystals

The coupling of upconversion nanophosphors （UCNPs） with the surface plasmonic resonance （SPR） of noble metals is a promising way to improve luminescent efficiency of UCNPs; however, it is still a challenge to achieve stable, reproducible and effective upconversion luminescence （UCL） enhancement through such coupling. In this work, we present a novel strategy to improve UCL of NaYF4：ybB,Er3. UCNPs, by combining the near-field coupling of SPR of silver and the far-field coupling of poly（methyl methacrylate） （PMMA） opal photonic crystals （OPCs） with the UCNPs. In order to control the effective interaction distance between the UCNPs and the SPR, a porous silver film consisting of randomly distributed silver nanoparticles （NPs） （〉 100 nm） was prepared which demonstrated strong SPR over a broad wavelength range, and its coupling to the UCNPs was found to be much stronger than that of a dense film. In the far-field coupling of OPCs, the photonic stop band （PSB） of the PMMA OPCs was tuned to 980 nm, matching exactly the excitation light. By modulating the particle size of the UCNPs, and the direction and excitation power of the incident light, a maximum enhancement of 60-fold was observed, which is an important advance for metaMnduced UCL enhancement systems.     

Characterisation of blends between poly(ε-caprolactone) and polysaccharides for tissue engineering applications

In this work, bioartificial binary blends between poly(ε-caprolactone) (PCL) and a polysaccharide (chitosan (CS) or starch (S)) with different contents of the natural polymer (5–30 wt.%) were produced. Melt-mixing and double-precipitation were the methods used for the obtainment of PCL/S and PCL/CS blends, respectively. Tubular scaffolds were produced from bioartificial blends by melt-extrusion. Physico-chemical characterisation was performed by differential scanning calorimetry analysis (DSC), thermogravimetry (TGA), scanning electron microscopy (SEM), infrared analysis (FTIR-ATR and micro-ATR mapping), atomic force microscopy (AFM) and stress–strain tests. Blends were not miscible, phase-separated systems, showing a homogeneous composition and morphology only at low polysaccharide content (≤ 10 wt.%). The biocompatibility of bioartificial guides was investigated by culturing NIH-3T3 mouse fibroblasts. Cells response showed the following order: PCL/S > PCL > PCL/CS. For each blend type, biocompatibility increased with decreasing the polysaccharide content. In vitro cell tests using S5Y5 neuroblastoma cells, carried out on the most biocompatible blends, assessed their absence of cytotoxicity towards these model cells of the nervous tissue. Results showed that blends with a low chitosan or starch content (≤ 10 wt.%) are promising for the regeneration of tissues requiring tubular scaffolds, such as the peripheral nerves.     

Spectroscopic and electrochemical properties of poly(2,5 dimethyl aniline) films

UV–visible, IR and redox characteristics of electrochemically deposited poly(2,5 dimethyl aniline) films are affected by varying the monomer concentration (0.025, 0.05 and 0.1 M) and dopant anions in the electrolyte solution (HCl, HClO₄ and H₂SO₄). The optical spectra show the presence of reduced leucoemeraldine phase 320 nm and emeraldine salt phase 740 nm in HCl and HClO₄ while in case of H₂SO₄ media the pernigraniline phase is observed 540 nm. The magnitude of absorbance is highest in H₂SO₄>HCl>HClO₄. On the other hand, the selectivity in the formation of conducting phase is greater in HCl in comparison with HClO₄ and H₂SO₄. IR spectra of the film reveal a higher ratio for the relative intensities of the quinoid to benzenoid ring modes i.e. I₁₅₁₀/I₁₄₄₀ in case of films deposited in H₂SO₄. Cyclic voltammograms show the presence of a single redox couple in each case except for H₂SO₄ where an additional anodic peak is observed. However, the increase in current is highest in HCl>HClO₄>H₂SO₄ hence, the thickness of the films calculated for the cathodic peak are in accordance with the current.     

Preparation of amorphous calcium carbonate nanoparticles from impure dolomitic marble with the aid of poly(acrylic acid) as a stabilizer

Nanomaterials of Precipitated Calcium Carbonate (PCC) such as Amorphous Calcium Carbonate (ACC) nanoparticles are highly demanded industrial products. These products are prepared in industrial scale, using pure CaCO₃ natural resources such as pure carbonate rocks, cockle shells, corals, and pearls. Such natural resources could be consumed rapidly due to their excessive use in PCC industries. Therefore, the development of novel procedures to prepare nanoparticles of PCC using impure minerals is desirable. Herein, we report a simple, novel and economical method to synthesize poly(acrylic acid) (PAA) stabilized ACC nanoparticles using extensively distributed impure dolomitic marbles in place of natural pure CaCO₃ raw materials. The yields of final ACC products are enhanced using a bubbling column which can produce small bubbles to improve bubbling efficiency. The average particle sizes of final calcium carbonate products are in the range 21–53 nm. The best conditions to produce ACC, among the conditions used in the proposed method, are temperature of 40 °C, pH of 4.5 and PAA concentration of 10⁻² M. One or more crystalline phase(s) of PCC is associated with ACC in each product and its nature depends on the conditions used in the synthesis of these products. The unstable vaterite form of PCC is formed when the PAA concentration is less than 0.5 M and at lower temperatures such as room temperature. The stability of the vaterite phase decreases when the temperature and the PAA concentration are increased. The synthesized ACC nanoparticles are in required purity and quality to be suitable for industrial applications.