Shigan Chai

Review of macroporous materials as electrochemical supercapacitor electrodes

Benefitting from excellent reversibility, high power density, and long cycle lifetime, electrochemical supercapacitors have become a versatile solution to meet the needs of various emerging energy storage applications. Their performances depend strongly on the properties of electrode materials. The composition, morphology, and structure are considered as the most important factors affecting the performances of electrode materials. Many previous review articles have discussed the research advances of some SC electrode materials with similar chemical compositions or microscopic morphologies. However, few review articles put their focus on the specific microstructures. Macropores, as a typical microstructure, can serve as ion-buffering reservoirs to minimize the diffusion distances of electrolyte. Thus, tremendous research efforts have been recently made to design and construct macropores for electrode materials to improve supercapacitive performance. Therefore, in this article, we review the recent developments of macroporous materials for SC applications, primarily including the preparation, microstructure, and performance of macroporous electrode materials. Typical five categories of macroporous electrode materials, including biomass-derived macroporous carbons, non-biomass-derived macroporous carbons, non-carbon-based macroporous materials, macroporous carbon-based composite materials, and active materials supported on macroporous substrates, are discussed in detail. Since mesopores can decrease ion-transport resistance, and micropores favor in-depth interfacial interactions, most porous electrode materials with excellent performance usually contain hierarchical porous structures consisting of macropores, mesopores, and micropores. Thus, the synergistic effects of hierarchical porous structures of various electrode materials are also indicated and summarized in this article. In addition, we also describe the influences of architecture’s several factors on the performance, and the differences in architecture of five categories of electrode materials. Finally, we present our perspectives on the challenges and prospects of macroporous electrode materials.

A novel, molecularly imprinted polymer sensor made using an oligomeric methyl silsesquioxane-TiO2 composite sol on a glassy carbon electrode for the detection of procainamide hydrochloride.

In this study, we designed a novel molecularly imprinted polymer (MIP), oligomeric methyl silsesquioxane (O-MSSQ)-TiO2 composite sol, which was made using a sol-gel reaction. This polymer has structural rigidity and high surface area of O-MSSQ, as well as high bio-compatibility and relatively good conductivity of the TiO2. Next, a sensitive and selective imprinted electrochemical sensor was successfully constructed for the direct detection of procainamide hydrochloride by molecularly imprinting a film onto the surface of a glassy carbon electrode. Adding TiO2 resulted in a noticeable enhancement in the sensitivity of the MIP sensor. The performance of the O-MSSQ-TiO2 film was discussed, and the optimal conditions for detection were determined. The oxidative peak current increased linearly with the concentration of procainamide hydrochloride in the range of 4.00 × 10(-9)-4.97 × 10(-5) M using differential pulse voltammetry, and the detection limit was 1.30 × 10(-9) M with S/N = 3. Furthermore, the sensor was applied to determine the procainamide hydrochloride content in a human blood serum sample. The recoveries of the sensors varied from 96.77% to 101.35%, indicating that the prepared sensor might be promising for the determination of procainamide hydrochloride in clinical tests. Moreover, the imprinted electrochemical sensor was used to selectively detect procainamide hydrochloride. The analytical application was conducted successfully and yielded accurate and precise results.

Resonance light scattering method for the determination of DNA with cationic methacrylate based polymer nanoparticle probes

Narrowly distributed cationic poly (methyl methacrylate-co-diacetone acrylamide) (P(MMA-DAAM)) nanoparticles were successfully prepared by microemulsion polymerization. Photon correlation spectrometer (PCS) measurement and transmission electron microscope (TEM) observation revealed that z-average particle size of P(MMA-DAAM) is ∼27.5 nm. It was found that these cationic nanoparticles interact with DNA through electrostatic interaction to form P(MMA-DAAM)-DNA complex, which significantly enhances the resonance light scattering (RLS) signal. Therefore, a novel method using this polymer nanoparticle as a new probe for the detection of DNA by RLS technique is developed in this paper. The results showed this method is very convenient, sensitive, and reproducible.

Stable poly(St-co-BA) nanoemulsion polymerization for high performance antibacterial coatings in the presence of dioctyldimethylammonium chloride.

In this study, a stable antibacterial poly(styrene-co-butyl acrylate) (poly(St-co-BA)) nano-latex was prepared in the presence of a dioctyldimethylammonium chloride (D821)-CTAB mixed surfactant and a novel bis-unsaturated Gemini comonomer (i.e., α,ω-hexanediyl bis(dimethyl methacrylamidopropyl ammonium bromide) (GMAP-6-MAP)) using a feasible and mild semicontinuous technology. The effects of the emulsifiers and GMAP-6-MAP on the properties and antibacterial activities of poly(St-co-BA) coatings were systematically investigated. The results indicate that an optimal monodispersed stable nanoemulsion was obtained with Dw=58.24nm and PDI=0.026, the emulsifier amount was 3.75% (D821/CTAB=4:1), and the GMAP-6-MAP amount was 1.5%. CTAB improved the stabilities and antibacterial activities of the poly(St-co-BA) nanoemulsions. The incorporation of GMAP-6-MAP into poly(St-co-BA) can enhance the antibacterial activity, improve the thermal stability of latex films, as well as the consistency among the chain segments, and decrease the roughness of latex films. This nanoemulsion exhibits effective antibacterial activity with MBCs of 2μg·mL(-1) against Staphylococcus aureus and 16μg·mL(-1) against Escherichia coli. The sterilization rates of the optimized latex film reached 100% against S. aureus and 98.74% against E. coli, which indicated that this latex film could be utilized as an outstanding antibacterial coating.

A novel sensor made of Antimony Doped Tin Oxide-silica composite sol on a glassy carbon electrode modified by single-walled carbon nanotubes for detection of norepinephrine

In this study, we designed a novel molecularly imprinted polymer (MIP), Antimony Doped Tin Oxide (ATO)-silica composite sol, which was made using a sol-gel method. Then a sensitive and selective imprinted electrochemical sensor was constructed with the ATO-silica composite sol on a glassy carbon electrode modified by single-walled carbon nanotubes (SWNTs). The introduction of SWNTs increased the sensitivity of the MIP sensor. The surface morphology of the MIP and MIP/SWNTs were characterized by scanning electron microscopy (SEM), and the optimal conditions for detection were determined. The oxidative peak current increased linearly with the concentration of norepinephrine in the range of 9.99×10-8M to 1.50×10-5M, as detected by cyclic voltammetry (CV), the detection limit was 3.33×10-8M (S/N=3). In addition, the proposed electrochemical sensors were successfully applied to detect the norepinephrine concentration in human blood serum samples. The recoveries of the sensors varied from 99.67% to 104.17%, indicating that the sensor has potential for the determination of norepinephrine in clinical tests. Moreover, the imprinted electrochemical sensor was used to selectively detect norepinephrine. The analytical application was conducted successfully and yielded accurate and precise results.

Application of Gemini quaternary ammonium with ester groups in cationic P(St-co-BA) nanolatex and study on its antibacterial properties

Novel Gemini quaternary ammonium salts (GQASs) with ester groups were synthesized. Cationic poly(styrene-co-butyl acrylate) (P(St-co-BA)) nanolatex was synthesized in the presence of GQASs as emulsifier. The structures of GQASs were characterized with Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy; the property of P(St-co-BA) nanolatex was characterized with dynamic light scattering. The results indicated that GQASs and P(St-co-BA) nanolatex with GQASs were successfully synthesized. GQASs, nanolatex, and the polymer films exhibited excellent antibacterial activities against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The GQASs performed even better than the corresponding single-stranded quaternary ammoniums. The antibacterial mechanism was also preliminarily studied, and longer, softer hydrophobic chains of GQAS had stronger antibacterial activity. The work provided a novel, simple approach for developing high-efficiency antibacterial polymer material with a low cost, which has broad biomaterial applications.

Influence of reactive POSS and DDP on thermal stability and flame retardance of UPR nanocomposites

Abstract Unsaturated polyester resins (UPR) were prepared by the melt condensation method based on adipic acid, o-phthalic anhydride, maleic anhydride and ethylene glycol in the presence of PSS-(2,3-propanediol)propoxy-heptaisobutyl substituted (PSS-POSS) or/and 9 wt% [(6-oxide-6H-dibenz(c,e)(1,2)oxaphosphorin-6-yl)methyl]butanedioic (DDP). We synthesized UPR containing DDP (DDP-UPR) and UPR containing both DDP and PSS-POSS (DDP-PSS-POSS-UPR series). The chemical structures of the modified polyesters were characterized and confirmed by Fourier transform infrared (FTIR) and 31P nuclear magnetic resonance (31P NMR). The thermal stability and flammability behaviors of UPR were evaluated by thermogravimetric analysis (TGA) and limited oxygen index (LOI) and the vertical burning test. The morphology of residual char of UPR was shown by scanning electron microscopy (SEM). The results indicate that the incorporation of PSS-POSS has little influence on the thermal stability of DDP-UPR, but enhances the flame retardance of DDP-UPR, and when the PSS-POSS content reaches 10 wt%, the DDP-PSS-POSS-UPR has better flame retardance.

Interaction in Binary Mixtures of Gemini Surfactant G12-6-12 and CTAB by NMR

The interaction between N, N′-bis(dimethyldodecyl)-1,6-hexanediammoniumdibromide (G12-6-12) and cetyltrimethylammonium bromide (CTAB) in D2O aqueous medium has been investigated by NMR at 298 K. The measured critical micelle concentration (cmc) of G12-6-12 and CTAB are about 0.773 and 0.668 mmol/L, respectively. The cmc* (cmc of mixture) values are less than CMC* (cmc of ideally mixed solution) in the mixed system, and the interaction parameter βM ∣ln(cmc1/cmc2)∣ (cmc1: cmc of pure G12-6-12 and cmc2: cmc of pure CTAB). The results indicate that there exists synergism between G12-6-12 and CTAB, and they can form mixed micelles, which is further proven by 2D NOESY and self-diffusion coefficient D experiments. There are intermolecular cross peaks between G12-6-12 and CTAB in 2D NOESY, and the radius of micelles in mixed solution is bigger than that in G12-6-12 pure solution in D experiments, indicating there are mixed micelles. However, when α>0.3, we find that cmc*≈CMC*, βM≈0, obviously, the two surfactants are almost ideal mixing fitting the pseudo-phase separation model and regular solution theory.