Synthesis of Inorganic–Organic 2D CdSe Slab‐Diamine Quantum Nets

Porous semiconductors attract great interest due to their unique structural characteristics of high surface area as well as their intrinsic optical and electronic properties. In this study, synthesis of inorganic–organic 2D CdSe slabs‐diaminooctane (DAO) porous quantum net structures is demonstrated. It is found that the hybrid 2D CdSe‐DAO lamellar structures are disintegrated into porous net structures, maintaining an ultrathin thickness of ≈1 nm in CdSe slabs. Furthermore, the CdSe slabs in quantum nets show the highly shifted excitonic transition in the absorption spectrum, demonstrating their strongly confined electronic structures. The possible formation mechanism of this porous structure is investigated with the control experiments of the synthesis using n‐alkyldiamines with various hydrocarbon chain lengths and ligand exchange of DAO with oleylamine. It is suggested that a strong van der Waals interaction among long chain DAO may exert strong tensile stress on the CdSe slabs, eventually disintegrating slabs. The thermal decomposition of CdSe‐DAO quantum nets is further studied to form well‐defined CdSe nanorods. It is believed that the current CdSe‐DAO quantum nets will offer a new type of porous semiconductors nanostructures under a strong quantum‐confinement regime, which can be applied to various technological areas of catalysts, electronics, and optoelectronics.     

New Concepts and Applications in the Macromolecular Chemistry of Fullerenes

A new classification on the different types of fullerene‐containing polymers is presented according to their different properties and applications they exhibit in a variety of fields. Because of their interest and novelty, water‐soluble and biodegradable C₆₀‐polymers are discussed first, followed by polyfullerene‐based membranes where unprecedented supramolecular structures are presented. Next are compounds that involve hybrid materials formed from fullerenes and other components such as silica, DNA, and carbon nanotubes (CNTs) where the most recent advances have been achieved. A most relevant topic is still that of C₆₀‐based donor‐acceptor (D–A) polymers. Since their application in photovoltaics D–A polymers are among the most realistic applications of fullerenes in the so‐called molecular electronics. The most relevant aspects in these covalently connected fullerene/polymer hybrids as well as new concepts to improve energy conversion efficiencies are presented. The last topics disccused relate to supramolecular aspects that are in involved in C₆₀‐polymer systems and in the self‐assembly of C₆₀‐macromolecular structures, which open a new scenario for organizing, by means of non‐covalent interactions, new supramolecular structures at the nano‐ and micrometric scale, in which the combination of the hydrofobicity of fullerenes with the versatility of the noncovalent chemistry afford new and spectacular superstructures.     

Nitrogen‐Containing Microporous Conjugated Polymers via Carbazole‐Based Oxidative Coupling Polymerization: Preparation,Porosity, and Gas Uptake

Facile preparation of microporous conjugated polycarbazoles via carbazole‐based oxidative coupling polymerization is reported. The process to form the polymer network has cost‐effective advantages such as using a cheap catalyst, mild reaction conditions, and requiring a single monomer. Because no other functional groups such as halo groups, boric acid, and alkyne are required for coupling polymerization, properties derived from monomers are likely to be fully retained and structures of final polymers are easier to characterize. A series of microporous conjugated polycarbazoles ( CPOP‐2–7 ) with permanent porosity are synthesized using versatile carbazolyl‐bearing 2D and 3D conjugated core structures with non‐planar rigid conformation as building units. The Brunauer–Emmett–Teller specific surface area values for these porous materials vary between 510 and 1430 m² g^?1. The dominant pore sizes of the polymers based on the different building blocks are located between 0.59 and 0.66 nm. Gas (H₂ and CO₂) adsorption isotherms show that CPOP‐7 exhibits the best uptake capacity for hydrogen (1.51 wt% at 1.0 bar and 77 K) and carbon dioxide (13.2 wt% at 1.0 bar and 273 K) among the obtained polymers. Furthermore, its high CH₄/N₂ and CO₂/N₂ adsorption selectivity gives polymer CPOP‐7 potential application in gas separation.     

炔丙基酰胺单体的共聚反应及共聚物的螺旋结构

为获得主链规整性高且能形成稳定螺旋结构的炔丙酰胺聚合物,实施了单体M1与单体M2的共聚反应。均聚物1不能形成螺旋结构,均聚物2只有在较低温度下才能形成螺旋结构。不同单体1/2比例的聚合体系,其共聚反应均能顺利进行;共聚物产率高于85%、主链规整性很高(顺式含量大于92%)。通过测定紫外-可见吸收谱图表明,共聚物均能形成螺旋结构,并且与均聚物2相比,共聚物所形成的螺旋结构的热稳定性明显改善。     

Integrative Approaches to Hybrid Multifunctional Materials: From Multidisciplinary Research to Applied Technologies

Achieving nanostructured or hierarchical hybrid architectures involves cross‐cutting synthetic strategies where all facettes of chemistry (organic, polymers, solid‐state, physical, materials chemistries, biochemistry, etc…?), soft matter and ingenious processing are synergistically coupled. These cross‐cutting approaches are in the vein of bio‐inspired synthesis strategies where the integration of different areas of expertise allows the development of complex systems of various shapes with perfect mastery at different size scales, composition, porosity, functionality, and morphology. These strategies coined “Integrative Chemistry” open a land of opportunities to create advanced hybrid materials with organic‐inorganic or bio‐inorganic character. These hybrid materials represent not only a new field of basic research where creative chemists can express themselves, but also, via their remarkable new properties and multifunctional nature, hybrids are allowing the emergence of innovative industrial applications in extremely diverse fields.     

丙烯基醚-丙烯酸酯杂化单体的合成及光聚合动力学研究

自由基光聚合和阳离子光聚合技术中各自存在着固有不足之处，诸如挥发性强，氧气阻聚作用大，收缩率高或者固化速度慢，水分影响严重等。 杂化光聚合体系是一种可以改善这些不足的方法，它可以分为混合杂化体系和杂化单体体系两种。其中杂化单体是指包含两种不同反应机理的活性基团，并通过化学键连结的单体，这种结构将改变两种官能团的光聚合动力学性质，并且使通过两种光聚合机理形成的聚合物成为均匀一致的、通过化学键相连的互穿网络结构，从而提高其机械物理性能。 本文合成了一种新型的丙烯基醚-丙烯酸酯杂化单体-丙烯氧基丙氧基丙烯酸酯（PPA），并应用实时变换傅立叶红外光谱法（RT—FTIK）对其进行了光聚合动力学研究。结果表明，在以硫锚盐为光引发剂时，这种杂化单体可以有效进行杂化光聚合反应，丙烯基醚和丙烯酸酯双键都显示出了较快的反应速度和较高的最终转化率。与混合杂化体系相比，每种基团的反应动力学性质都得到了促进，同时这种杂化单体结构还降低了羟基对于烯基醚基团光聚合的影响。这将为开发新型的光聚合活性单体开创新的途径和方法。     

Cover Picture: Combinatorial Material Mechanics: High‐Throughput Polymer Synthesis and Nanomechanical Screening (Adv. Mater. 21/2005)

The automated synthesis and nanomechanical characterization of discrete combinatorial arrays of polymers enables high‐throughput discovery and analysis of compliant, functional materials, as shown by Van Vliet and co‐workers on p. 2599. The cover illustrates a triplicate array of 576 polymers automatically printed on a glass microscope slide, where each spot represents a pairwise, systematically varied composition among 24 different monomers. Overlaid on the image of this triplicate array is a differential interference contrast image of a single nanoliter‐scale polymer volume. In less than twenty‐four hours of synthesis and mechanical characterization, the stiffness of each polymer is determined and related to key monomer structures and volume fractions thereof.     

Confining Tiny MoO2 Clusters into Reduced Graphene Oxide for Highly Efficient Low Frequency Microwave Absorption

Herein, a supermolecular‐scale cage‐confinement pyrolysis strategy is proposed to build two dielectric electromagnetic wave absorbents, in which MoO₂ nanoparticles are sandwiched uniformly between porous carbon shells and reduced graphene oxide (RGO). Both sandwich structures are derived from hybrid hydrogels doped by two different crosslinkers (with/without oxygen bridge), which can precisely confine Mo source (e.g., PMo₁₂). Without adding magnetic components, both absorbents exhibit excellent low frequency absorption performance in combination with electrically tunable ability and enhanced reflection loss value, which is superior over other relative 2D dielectric absorbers and satisfies the requirements of portable electronics. Notably, introducing oxygen bridges in the crosslinker generates a more stable confining configuration, which in turn renders its corresponding derivative exhibiting an extra multifrequency electromagnetic wave absorption trait. The intrinsic electromagnetic wave adjustment mechanism of the ternary hybrid absorbent is also explored. The result reveals that the elevated electromagnetic wave absorbing property is attributed to moderate attenuation constant and glorious impendence matching. The cage‐confinement pyrolysis route to fabricate 2D MoO₂‐based dielectric electromagnetic wave absorbents opens a new path for the design of electromagnetic wave absorbents used in multi/low frequency.     

Photocontrolled living polymerizations

Living polymerizations involve the creation of polymer chains without significant irreversible chain transfer or chain termination. Such processes are widely used to access well-defined macromolecular materials with controlled architectures, such as block and star polymers. Although this concept was first realized for anionic polymerizations in the 1950s, many key recent advances have been made, most notably in the area of radical polymerization. Here, we report a living photopolymerization that involves photoexcited monomers. Exposure of metal-containing ferrocenophane monomers to Pyrex-filtered light from a mercury lamp (lambda>310 nm) or to bright sunlight in the presence of an anionic initiator leads to living polymerizations, in which the conversion and molecular weight of the resulting polymer can be controlled by the irradiation time. Photoirradiation selectively weakens the iron-cyclopentadienyl bond in the monomer, allowing the use of moderately basic and highly functional-group-tolerant initiators. The polymerization proceeds through attack of the initiator and propagating anion on the iron atom of the photoexcited monomer and, remarkably, the polymerization rate decreases with increasing temperature. Block copolymer formation is possible when the light source is alternately switched on and off in between sequential addition of different monomers, providing unprecedented, photocontrolled access to new types of functional polymers.     

Synthetic Light‐Curable Polymeric Materials Provide a Supportive Niche for Dental Pulp Stem Cells

Dental disease annually affects billions of patients, and while regenerative dentistry aims to heal dental tissue after injury, existing polymeric restorative materials, or fillings, do not directly participate in the healing process in a bioinstructive manner. There is a need for restorative materials that can support native functions of dental pulp stem cells (DPSCs), which are capable of regenerating dentin. A polymer microarray formed from commercially available monomers to rapidly identify materials that support DPSC adhesion is used. Based on these findings, thiol‐ene chemistry is employed to achieve rapid light‐curing and minimize residual monomer of the lead materials. Several triacrylate bulk polymers support DPSC adhesion, proliferation, and differentiation in vitro, and exhibit stiffness and tensile strength similar to existing dental materials. Conversely, materials composed of a trimethacrylate monomer or bisphenol A glycidyl methacrylate, which is a monomer standard in dental materials, do not support stem cell adhesion and negatively impact matrix and signaling pathways. Furthermore, thiol‐ene polymerized triacrylates are used as permanent filling materials at the dentin‐pulp interface in direct contact with irreversibly injured pulp tissue. These novel triacrylate‐based biomaterials have potential to enable novel regenerative dental therapies in the clinic by both restoring teeth and providing a supportive niche for DPSCs.     

Isomeric Routes to Schiff‐Base Single‐layered Covalent Organic Frameworks

With graphene‐like topology and designable functional moieties, single‐layered covalent organic frameworks (sCOFs) have attracted enormous interest for both fundamental research and application prospects. As the growth of sCOFs involves the assembly and reaction of precursors in a spatial defined manner, it is of great importance to understand the kinetics of sCOFs formation. Although several large families of sCOFs and bulk COF materials based on different coupling reactions have been reported, the synthesis of isomeric sCOFs by exchanging the coupling reaction moieties on precursors has been barely explored. Herein, a series of isomeric sCOFs based on Schiff‐base reaction is designed to understand the effect of monomer structure on the growth kinetics of sCOFs. The distinctly different local packing motifs in the mixed assemblies for the two isomeric routes closely resemble to those in the assemblies of monomers, which affect the structural evolution process for highly ordered imine‐linked sCOFs. In addition, surface diffusion of monomers and the molecule‐substrate interaction, which is tunable by reaction temperature, also play an important role in structural evolutions. This study highlights the important roles of monomer structure and reaction temperature in the design and synthesis of covalent bond connected functional nanoporous networks.     

Metal‐containing Polymers via Electropolymerization

Electropolymerization represents a suitable and well‐established approach for the assembly of polymer structures, in particular with regard to the formation of thin, insoluble films. Utilization of monomers that are functionalized with metal complex units allows the combination of structural and functional benefits of polymers and metal moieties. Since a broad range of both electropolymerizable monomers and metal complexes are available, various structures and, thus, applications are possible. Recent developments in the field of synthesis and potential applications of metal‐functionalized polymers obtained via electropolymerization are presented, highlighting the significant advances in this field of research.     

Design of Multifunctional Fluorescent Hybrid Materials Based on SiO2 Materials and Core–Shell Fe3O4@SiO2 Nanoparticles for Metal Ion Sensing

Hybrid fluorescent materials constructed from organic chelating fluorescent probes and inorganic solid supports by covalent interactions are a special type of hybrid sensing platform that has gained much interest in the context of metal ion sensing applications owing to their excellent advantages, recyclability, and solubility/dispersibility in particular, as compared with single organic fluorescent molecules. In recent decades, SiO₂ materials and core–shell Fe₃O₄@SiO₂ nanoparticles have become important inorganic solid materials and have been used as inorganic solid supports to hybridize with organic fluorescent receptors, resulting in multifunctional fluorescent hybrid systems for potential applications in sensing and related research fields. Therefore, recent progress in various fluorescent‐group‐functionalized SiO₂ materials is reviewed, with a focus on mesoporous silica nanoparticles and core–shell Fe₃O₄@SiO₂ nanoparticles, as interesting fluorescent organic–inorganic hybrid materials for sensing applications toward essential and toxic metal ions. Selective examples of other types of silica/silicon materials, such as periodic mesoporous organosilicas, solid SiO₂ nanoparticles, fibrous silica spheres, silica nanowires, silica nanotubes, and silica hollow microspheres, are also mentioned. Finally, relevant perspectives of metal‐ion‐sensing‐oriented silica‐fluorescent probe hybrid materials are provided.     

Shape‐Shifting 3D Protein Microstructures with Programmable Directionality via Quantitative Nanoscale Stiffness Modulation

The ability to shape‐shift in response to a stimulus increases an organism's survivability in nature. Similarly, man‐made dynamic and responsive “smart” microtechnology is crucial for the advancement of human technology. Here, 10–30 μm shape‐changing 3D BSA protein hydrogel microstructures are fabricated with dynamic, quantitative, directional, and angle‐resolved bending via two‐photon photolithography. The controlled directional responsiveness is achieved by spatially controlling the cross‐linking density of BSA at a nanometer lengthscale. Atomic force microscopy measurements of Young's moduli of structures indicate that increasing the laser writing distance at the z‐axis from 100–500 nm decreases the modulus of the structure. Hence, through nanoscale modulation of the laser writing z‐layer distance at the nanoscale, control over the cross‐linking density is possible, allowing for the swelling extent of the microstructures to be quantified and controlled with high precision. This method of segmented moduli is applied within a single microstructure for the design of shape‐shifting microstructures that exhibit stimulus‐induced chirality, as well as for the fabrication of a free‐standing 3D microtrap which is able to open and close in response to a pH change.     

Polyindole-Au nanocomposite produced at the liquid/liquid interface

This letter is a continuation of our previous work on synthesis of polyindole-gold nanocomposite published in this journal. In the present work, we have synthesized the similar hybrid organo-inorganic composite using a novel interfacial polymerization route at water/dichloromethane interface. The hybrid organo-inorganic composite material is based on conducting polymer, polyindole and gold nanoparticles; the redox character of indole (monomer) and chloroauric acid facilitates the polymerization of monomer. Entirely different morphological and structural features are observed compared to our previous results. The contact of monomer and metal salt acid (chloroauric acid) at the interface results in the formation of polyindole-Au nanocomposite (without any need of template or capping agent) of nanorod morphology encapsulating Au nanoparticles. XRD studies shows semi-crystalline nature of the polymer unlike the amorphous polyindole formed using other methods. Tunable photoluminescence spectra show the potential applications of the composite in the field of organic laser and organic optoelectronics.     

Complex Nanostructures from Materials based on Metal–Organic Frameworks for Electrochemical Energy Storage and Conversion

Metal–organic frameworks (MOFs) have drawn tremendous attention because of their abundant diversity in structure and composition. Recently, there has been growing research interest in deriving advanced nanomaterials with complex architectures and tailored chemical compositions from MOF‐based precursors for electrochemical energy storage and conversion. Here, a comprehensive overview of the synthesis and energy‐related applications of complex nanostructures derived from MOF‐based precursors is provided. After a brief summary of synthetic methods of MOF‐based templates and their conversion to desirable nanostructures, delicate designs and preparation of complex architectures from MOFs or their composites are described in detail, including porous structures, single‐shelled hollow structures, and multishelled hollow structures, as well as other unusual complex structures. Afterward, their applications are discussed as electrode materials or catalysts for lithium‐ion batteries, hybrid supercapacitors, water‐splitting devices, and fuel cells. Lastly, the research challenges and possible development directions of complex nanostructures derived from MOF‐based‐templates for electrochemical energy storage and conversion applications are outlined.     

Solving structural optimization problems with genetic algorithms and simulated annealing

In this paper we study the performance of two stochastic search methods: Genetic Algorithms and Simulated Annealing, applied to the optimization of pin‐jointed steel bar structures. We show that it is possible to embed these two schemes into a single parametric family of algorithms, and that optimal performance (in a parallel machine) is obtained by a hybrid scheme. Examples of applications to the optimization of several real steel bar structures are presented. Copyright © 1999 John Wiley & Sons, Ltd.     

Robust Negative Electrode Materials Derived from Carbon Dots and Porous Hydrogels for High‐Performance Hybrid Supercapacitors

Hybrid supercapacitors generally show high power and long life spans but inferior energy densities, which are mainly caused by carbon negative electrodes with low specific capacitances. To improve the energy densities, the traditional methods include optimizing pore structures and modifying pseudocapacitive groups on the carbon materials. Here, another promising way is suggested, which has no adverse effects to the carbon materials, that is, constructing electron‐rich regions on the electrode surfaces for absorbing cations as much as possible. For this aim, a series of hierarchical porous carbon materials are produced by calcinating carbon dots–hydrogel composites, which have controllable surface states including electron‐rich regions. The optimal sample is employed as the negative electrode to fabricate hybrid supercapacitors, which show remarkable specific energy densities (up to 62.8–90.1 Wh kg^?1) in different systems.     

Hierarchical Electrohydrodynamic Structures for Surface‐Enhanced Raman Scattering

Surface enhanced Raman scattering (SERS) is a well‐established spectroscopic technique that requires nanoscale metal structures to achieve high signal sensitivity. While most SERS substrates are manufactured by conventional lithographic methods, the development of a cost‐effective approach to create nanostructured surfaces is a much sought‐after goal in the SERS community. Here, a method is established to create controlled, self‐organized, hierarchical nanostructures using electrohydrodynamic (HEHD) instabilities. The created structures are readily fine‐tuned, which is an important requirement for optimizing SERS to obtain the highest enhancements. HEHD pattern formation enables the fabrication of multiscale 3D structured arrays as SERS‐active platforms. Importantly, each of the HEHD‐patterned individual structural units yield a considerable SERS enhancement. This enables each single unit to function as an isolated sensor. Each of the formed structures can be effectively tuned and tailored to provide high SERS enhancement, while arising from different HEHD morphologies. The HEHD fabrication of sub‐micrometer architectures is straightforward and robust, providing an elegant route for high‐throughput biological and chemical sensing.     

The influence of process parameters on the structure and morphology of pulsed plasma‐polymerized octafluorotoluene films

Abstract

This work describes amorphous fluorinated polymer films deposited by pulsed plasma polymerizations of octafluorotoluene (PPP‐OFT) monomers on ITO glass as the hole‐injection layer of organic electroluminescent (EL) devices, in order to study the influence of sample position and duty cycle on PPP‐OFT film characteristics, and also to find a good process to yield a higher retention degree of monomers and lower roughness of PPP‐OFT fluorocarbon films. Experimental results revealed that PPP‐OFT films deposited at positions far away from the RF coil and close to the monomer inlet showed less roughness than films deposited near the high RF‐flux regions. In addition, the retention of the monomers in the PPP‐OFT layer will be high if the deposition is conducted near the monomer inlet but some distance away from the RF electrode. Moreover, amorphous fluorinated polymer films can be deposited with higher fluorine to carbon (F/C) ratios and CF₂ contents at proper substrate positions by means of different sticking coefficients of free radicals dissociated by octafluorotoluene monomers.