Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Fluorescent Chemosensors Based on Spiroring-Opening of Xanthenes and Related Derivatives Xiaoqiang Chen, Tuhin Pradhan, Fang Wang, Jong Seung Kim,* and Juyoung Yoon* Departments of Chemistry and Nano Science and of Bioinspired Science (WCU), Ewha Womans University, Seoul 120-750, Korea State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China Department of Chemistry, Korea University, Seoul 136-701, Korea

Fluorescent chemosensors based on spiroring-opening of xanthenes and related derivatives.

Molecular imprinting technology (MIT) concerns formation of selective sites in a polymer matrix with the memory of a template. Recently, molecularly imprinted polymers (MIPs) have aroused extensive attention and been widely applied in many fields, such as solid-phase extraction, chemical sensors and artificial antibodies owing to their desired selectivity, physical robustness, thermal stability, as well as low cost and easy preparation. With the rapid development of MIT as a research hotspot, it faces a number of challenges, involving biological macromolecule imprinting, heterogeneous binding sites, template leakage, incompatibility with aqueous media, low binding capacity and slow mass transfer, which restricts its applications in various aspects. This critical review briefly reviews the current status of MIT, particular emphasis on significant progresses of novel imprinting methods, some challenges and effective strategies for MIT, and highlighted applications of MIPs. Finally, some significant attempts in further developing MIT are also proposed (236 references).

http://ir.yic.ac.cn/bitstream/133337/4853/1/Recent%20advances%20in%20molecular%20imprinting%20technology%20current%20status%2c%20challenges%20and%20highlighted%20applications.pdf

Recent advances in molecular imprinting technology: current status, challenges and highlighted applications

Dingcai Wu,*,† Fei Xu,† Bin Sun,† Ruowen Fu,† Hongkun He,‡ and Krzysztof Matyjaszewski*,‡ †Materials Science Institute, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People's Republic of China ‡Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States

Design and Preparation of Porous Polymers

A novel, “all-in-one”, multifunctional microsphere with a fluorescent mesoporous silica shell (Rhodamine B coordinate receptor inside) and a magnetic core (Fe3O4) has been successfully fabricated using a sol–gel method and small molecular (CTAB) surfactants as structure-directing agents. At the same time, they were examined for environmental protection applications to detect, adsorb and remove Hg2+ in aqueous solution. The prepared nanocomposite microspheres were fluorescent, mesoporous, and magnetizable, with a diameter of 300–450 nm, a surface area of 600 m2 g−1, a pore size of 2.5 nm, and a saturation magnetization of 27.5 emu g−1. These multifuctional microspheres showed excellent fluorescence sensitivity and selectivity towards Hg2+ over other metal ions (Na+, Mg2+, Mn2+, Co2+, Ni2+, Zn2+, Cd2+, Ag+, Pb2+ and Cu2+). Upon the addition of Hg2+, an overall emission change of 16-fold was observed, and the detection limit of Hg2+ was as low as 10 ppb. The adsorption process of Hg2+ on the microspheres was well described by the Langmuir equation. The equilibrium can be established within five minutes and the adsorption capacity was 21.05 mg g−1. The concentration of Hg2+ ions can be reduced to less than 0.05 ppm and the used microspheres can be easily separated from the mixture by adding an external magnetic field. These results suggest that these “all-in-one” multifunctional nanocomposites are potentially useful materials for simultaneously rapidly detecting and recovering dangerous pollutants in aqueous solution.

Multifunctional mesoporous material for detection, adsorption and removal of Hg2+ in aqueous solution

Imprinted Photonic Polymers for Chiral Recognition

A series of porphyrin or metalloporphyrin-doped mesostructured silica films were successfully fabricated using small molecular (CTAB) or macromolecular (F127, P123) surfactants as structure-directing agents, and examined for chemosensor applications to detect trace vapors of explosives such as TNT and DNT. All prepared nanocomposite films show high fluorescence quenching sensitivity towards TNT and DNT vapors, but, their performances are strongly dependent on the formed mesostructure, the pore size and the type of sensing elements (porphyrin units). The cadmium porphyrin film with bicontinuous worm-like mesostructure exhibits the highest quenching efficiency, close to 60% after 10 s of exposure. Besides the superior TNT detecting capability, these hybrid films offer several advantages over other fluorescence-based sensory materials, such as a simple preparation procedure, inexpensive materials as well as the stability of organic sensing elements in an inorganic matrix. These results suggest that these new kinds of mesostructured nanocomposites are potentially useful chemosensory materials for rapidly detecting trace explosives.

Metalloporphyrins as sensing elements for the rapid detection of trace TNT vapor

Electrospinning is a simple and cost-effective approach for the production of nanofibers and assemblies with controllable structures. In this work, based on sol–gel chemistry and the electrospinning technique, porphyrin-doped nanocomposite fibers with a form of nanofibrous membrane were successfully fabricated without the addition or help of polymers, and were demonstrated as novel fluorescence-based chemosensors for the rapid detection of trace vapor (10 ppb) of explosive. Due to a larger surface area and good gas permeability, these fluorescent nanofibrous membranes exhibit remarkable sensitivity to trace TNT vapor compared to tightly cross-linked silica films, but their sensitivity is strongly dependent upon the morphology and phase aggregation of the used nanofibers. Reducing the diameter and introducing a pore structure into nanofibers can considerably enhance the sensitivity of the resulting materials. The performed experiments suggest that the hierarchically structured, porphyrin-doped nanofibrous membranes are potentially very useful chemosensory materials for detecting trace explosives.

Fluorescent nanofibrous membranes for trace detection of TNT vapor

A novel silane bearing a reactive anhydride group was synthesized. Due to its special structure, the direct co-condensation of this synthesized functional silane with TEOS in the presence of different surfactant templates led to ordered mesoporous silicas with different pore sizes and a high density of carboxylic acid groups, which were used as adsorbents for the removal of three basic dyestuffs (methylene blue, phenosafranine and night blue) from waste water. The performed measurements showed that, probably due to their high surface area, good affinity of carboxylic groups and large number of binding sites, the obtained mesoporous materials exhibit a high adsorption capacity and an extremely rapid adsorption rate. Furthermore, these carboxylic-functionalized adsorbents can be regenerated by simple washing with acid solution to recover both the adsorbents and the adsorbed dyes. The experimental data for the adsorption of all three basic dyes were analyzed using Langmuir and Redlich–Peterson isotherm models. It is found that the Langmuir equation provides an accurate description of these adsorption data, suggesting that monolayer adsorption occurred in all cases of the performed sorption processes. In this work, the influences of the pH values of the treated solutions and the pore sizes of the prepared adsorbents on the adsorption behavior were also discussed.

Shengyang Tao

Papers

Multifunctional mesoporous material for detection, adsorption and removal of Hg2+ in aqueous solution

Imprinted Photonic Polymers for Chiral Recognition

Metalloporphyrins as sensing elements for the rapid detection of trace TNT vapor

Fluorescent nanofibrous membranes for trace detection of TNT vapor

Mesoporous silicas functionalized with a high density of carboxylate groups as efficient absorbents for the removal of basic dyestuffs