ZigBee和GPRS技术在无线监控系统中的应用

为了使家居系统摆脱各种线缆的羁绊,设计了一种基于ZigBee和GPRS技术的智能家居系统。采用MSP430单片机和无线射频模块CC2420搭建了一个符合ZigBee规范的星型传感器网络,对温度、煤气、人体入侵进行实时采集,并通过GPRS网络对系统进行实时监控。实验结果表明,系统功耗小、可靠性高,是一种理想的智能家居实现方式。     

React‐on‐Demand (RoD) Fabrication of Highly Conductive Metal–Polymer Hybrid Structure for Flexible Electronics via One‐Step Direct Writing or Printing

As a fast prototyping technique, direct writing of flexible electronics is gaining popularity for its low‐cost, simplicity, ultrahigh portability, and ease of use. However, the latest handwritten circuits reported either have relative low conductivity or require additional post‐treatment, keeping this emerging technology away from end‐users. Here, a one‐step react‐on‐demand (RoD) method for fabricating flexible circuits with ultralow sheet resistance, enhanced safety, and durability is proposed. With the special functionalized substrate, a real‐time 3D synthesis of silver plates in microscale is triggered on‐demand right beneath the tip in the water‐swelled polyvinyl alcohol (PVA) coating, forming a 3D metal–polymer hybrid structure of ≈7 µm with one single stroke. The as‐fabricated silver traces show an enhanced durability and ultralow sheet resistance down to 4 mΩ sq^?1 which is by far the lowest sheet resistance reported in literatures achieved by direct writing. Meanwhile, PVA seal small particles inside the film, adding additional safety to this technology. Since neither nanomaterials nor a harsh fabrication environment are required, the proposed method remains low cost, user friendly, and accessible to end users. With little effort, the RoD approach can be extended to various printing systems, offering a particle‐free, sintering‐free solution for high‐resolution, high‐speed production of flexible electronics.     

Structure–Thermodynamic‐Property Relationships in Cyanovinyl‐Based Microporous Polymer Networks for the Future Design of Advanced Carbon Capture Materials

Nitrogen‐rich solid absorbents, which have been immensely tested for carbon dioxide capture, seem until this date to be without decisive molecular engineering or design rules. Here, a family of cyanovinylene‐based microporous polymers synthesized under metal‐catalyzed conditions is reported as a promising candidate for advanced carbon capture materials. These networks reveal that isosteric heats of CO₂ adsorption are directly proportional to the amount of their functional group. Motivated by this finding, polymers produced under base‐catalyzed conditions with tailored quantities of cyanovinyl content confirm the systematical tuning of their sorption enthalpies to reach 40 kJ mol^?1. This value is among the highest reported to date in carbonaceous networks undergoing physisorption. A six‐point‐plot reveals that the structure–thermodynamic‐property relationship is linearly proportional and can thus be perfectly fitted to tailor‐made values prior to experimental measurements. Dynamic simulations show a bowl‐shaped region within which CO₂ is able to sit and interact with its conjugated surrounding, while theoretical calculations confirm the increase of binding sites with the increase of Ph? C?C(CN)? Ph functionality in a network. This concept presents a distinct method for the future design of carbon dioxide capturing materials.     

Recent Progress in Applications of the Cold Sintering Process for Ceramic–Polymer Composites

Ceramic–polymer composites are of interest for designing enhanced and unique properties. However, the processing temperature windows of sintering ceramics are much higher than that of compaction, extrusion, or sintering of polymers, and thus traditionally there has been an inability to cosinter ceramic–polymer composites in a single step with high amounts of ceramics. The cold sintering process is a low‐temperature sintering technology recently developed for ceramics and ceramic‐based composites. A wide variety of ceramic materials have now been demonstrated to be densified under the cold sintering process and therefore can be all cosintered with polymers from room temperature to 300 °C. Here, the status, understanding, and application of cold cosintering, with different examples of ceramics and polymers, are discussed. One has to note that these types of cold sintering processes are yet new, and a full understanding will only emerge after more ceramic–polymer examples emerge and different research groups build upon these early observations. The general processing, property designs, and an outlook on cold sintering composites are outlined. Ultimately, the cold sintering process could open up a new multimaterial design space and impact the field of ceramic–polymer composites.     

Fabrication of Metal Oxides Occluded in Ordered Mesoporous Hosts via a Solid‐State Grinding Route: The Influence of Host–Guest Interactions

Solid‐state grinding is a simple and effective method to include guest species into the channels of ordered mesoporous materials with a different degree of filling. After calcination, a monolayer or several monolayers of guest species can not only form highly dispersed oxide species and other surface species on the hosts whether the template is occluded in the channels or not, but the guest species can also fill the mesoporous channels in the host and thus lead to nanowires or nanoarrays. Solid‐state salt inclusion is faster and more convenient than other inclusion routes. The absence of a solvent not only saves the time otherwise needed for evaporation but also leads to a higher degree of filling through a simple inclusion step as the void space in the pores is not occupied by the solvent. Also, the lack of competitive adsorption of solvent molecules enhances the interaction between the guest species included and the silica wall, which facilitates the high dispersion of oxide species. However, host–guest interactions that are too strong may disturb the self‐crystallization of guest species in the mesopores leading to imperfect nanocasting of the mesostructure.     

Probing the Dynamic Nature of Self‐Assembling Cyclic Peptide–Polymer Nanotubes in Solution and in Mammalian Cells

Self‐assembling cyclic peptide–polymer nanotubes have emerged as a fascinating supramolecular system, well suited for a diverse range of biomedical applications. Due to their well‐defined diameter, tunable peptide anatomy, and ability to disassemble in situ, they have been investigated as promising materials for numerous applications including biosensors, antimicrobials, and drug delivery. Despite this continuous effort, the underlying mechanisms of assembly and disassembly are still not fully understood. In particular, the exchange of units between individual assembled nanotubes has been overlooked so far, despite its knowledge being essential for understanding their behavior in different environments. To investigate the dynamic nature of these systems, cyclic peptide–polymer nanotubes are synthesized, conjugated with complementary dyes, which undergo a Förster resonance energy transfer (FRET) in close proximity. Model conjugates enable to demonstrate not only that their self‐assembly is highly dynamic and not kinetically trapped, but also that the self‐assembly of the conjugates is strongly influenced by both solvent and concentration. Additionally, the versatility of the FRET system allows studying the dynamic exchange of these systems in mammalian cells in vitro using confocal microscopy, demonstrating the exchange of subunits between assembled nanotubes in the highly complex environment of a cell.     

A Synergetic Effect of Molecular Weight and Fluorine in All‐Polymer Solar Cells with Enhanced Performance

A synergetic effect of molecular weight (M_n) and fluorine (F) on the performance of all‐polymer solar cells (all‐PSCs) is comprehensively investigated by tuning the M_n of the acceptor polymer poly((N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl)‐alt‐5,5′‐(2,2′‐bithiophene)) (P(NDI2OD‐T2)) and the F content of donor polymer poly(2,3‐bis‐(3‐octyloxyphenyl)quinoxaline‐5,8‐dyl‐alt‐thiophene‐2,5‐diyl). Both M_n and F variations strongly influence the charge transport properties and morphology of the blend films, which have a significant impact on the photovoltaic performance of all‐PSCs. In particular, the effectiveness of high M_n in increasing power conversion efficiency (PCE) can be greatly improved by the devices based on optimum F content, reaching a PCE of 7.31% from the best all‐PSC combination. These findings enable us to further understand the working principles of all‐PSCs with a view on achieving even higher power conversion efficiency in the future.     

The Effect of Annealing on the Charge‐Carrier Dynamics in a Polymer/Polymer Bulk Heterojunction for Photovoltaic Applications

The effect of annealing blends of poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylenevinylene) (MDMO‐PPV) and a poly(cyanoether phenylenevinylene) (PCNEPV) on the photoconductivity is studied. Charge carriers are generated by pulsed‐laser excitation and their mobility and decay kinetics are monitored using time‐resolved microwave conductivity (TRMC) measurements. Photoexcitation leads to the formation of an exciton, which can undergo charge separation at an interface between the electron‐donating MDMO‐PPV and the electron‐accepting PCNEPV. The electrons and holes formed in this way must escape from each other to contribute to the photoconductivity. The photoconductivity of the blends is found to increase by almost two orders of magnitude upon thermal annealing for three hours at 100 °C. This increase is attributed to the occurrence of phase separation in the polymer/polymer film, resulting in PCNEPV‐rich parts. The formation of PCNEPV‐rich parts allows the electron to diffuse away from the interface, which favors escape from geminate recombination, leading to a higher photoconductivity.     

Achieving a High Fill Factor and Stability in Perylene Diimide–Based Polymer Solar Cells Using the Molecular Lock Effect between 4,4′‐Bipyridine and a Tri(8‐hydroxyquinoline)aluminum(III) Core

Two novel perylene diimide (PDI)–based derivatives, Alq₃‐PDI and Alq₃‐PDI 2, are synthesized by flanking a 3D tri(8‐hydroxyquinoline)aluminum(III) (Alq₃) core with PDI and a helical PDI dimer (PDI2) to construct high‐performance small molecular nonfullerene acceptors (SMAs). The 3D Alq₃ core significantly suppresses the molecular aggregation of the resulting SMAs, leading to a well‐mixed blend with a PTTEA donor polymer and weak phase separation. Compared with Alq₃‐PDI , the extended π‐conjugation of Alq₃‐PDI2 results in higher‐order molecular packing, which improves the absorption and phase separation behavior. Thus, the Alq₃‐PDI2 devices have higher J_sc and FF values and better device performance, which are further enhanced by a small amount of 4,4′‐bipyridine (Bipy) as an additive. The coordination between Bipy and the Alq₃ core promotes molecular packing and phase separation, which lower charge recombination and enhanced charge collection in the resulting devices. Therefore, a largely improved J_sc of 15.74 mA cm^?2 and very high FF of 71.27% are obtained in the Alq₃‐PDI2 devices, resulting in a power conversion efficiency of 9.54%, which is the best value reported for PDI‐based polymer solar cells. The coordination can also serve as a “molecular lock,” which prevents molecular motion and thus improves device stability.