Functional Poly(ionic liquid) Porous Membranes: From Fabrications to Advanced Applications†

Polyelectrolyte porous membranes (PPMs) belong to the most interesting classes of materials, because the synergy of tunable pore sizes and charge nature of polyelectrolyte endow them with wide-ranging practical applications. However, owing to the water solubility and ionic nature of the polyelectrolytes, traditional polyelectrolytes are difficult to use in scalable preparation of high-quality PPMs through the well-developed industrial methods. Poly(ionic liquid)s (PIL) are a subclass of functional polyelectrolytes bearing ionic liquid groups in their repeating unites, inheriting the advantages of ionic liquids (ILs) and macromolecular architecture features. In recent years, along with rapid development of PIL materials chemistry, considerable and significant developments involving the novel preparation methods, and structure-property-function relationships of PPMs have been made. In this review, we highlight the latest discovery and proceedings of PPMs, particularly the advancements in how to tailor structures and properties of PPMs by rational structure design of PILs. The formation mechanisms of various PPMs were also discussed in detail from the viewpoint of PILs molecular structures. A future perspective of the challenges and promising potential of PPMs is cast on the basis of these achievements. We expect that these analyses and deductions will be useful for the design of useful PPMs and serve as a source of inspiration for the design of future multifunctional PPMs.      

Infrared Fingerprint Engineering: A Molecular‐Design Approach to Long‐Wave Infrared Transparency with Polymeric Materials

Optical technologies in the long‐wave infrared (LWIR) spectrum (7–14 μm) offer important advantages for high‐resolution thermal imaging in near or complete darkness. The use of polymeric transmissive materials for IR imaging offers numerous cost and processing advantages but suffers from inferior optical properties in the LWIR spectrum. A major challenge in the design of LWIR‐transparent organic materials is that nearly all organic molecules absorb in this spectral window which lies within the so‐called IR‐fingerprint region. We report on a new molecular‐design approach to prepare high refractive index polymers with enhanced LWIR transparency. Computational methods were used to accelerate the design of novel molecules and polymers. Using this approach, we have prepared chalcogenide hybrid inorganic/organic polymers (CHIPs) with enhanced LWIR transparency and thermomechanical properties via inverse vulcanization of elemental sulfur with new organic co‐monomers.     

Self-assembled gelators for organic electronics

Nature excels at engineering materials by using the principles of chemical synthesis and molecular self-assembly with the help of noncovalent forces. Learning from these phenomena, scientists have been able to create a variety of self-assembled artificial materials of different size, shapes, and properties for wide ranging applications. An area of great interest in this regard is solvent-assisted gel formation with functional organic molecules, thus leading to one-dimensional fibers. Such fibers have improved electronic properties and are potential soft materials for organic electronic devices, particularly in bulk heterojunction solar cells. Described herein is how molecular self-assembly, which was originally proposed as a simple laboratory curiosity, has helped the evolution of a variety of soft functional materials useful for advanced electronic devices such as organic field-effect transistors and organic solar cells. Highlights on some of the recent developments are discussed.     

Polyphosphates as inorganic polyelectrolytes interacting with oppositely charged ions,polymers and deposited on surfaces: fundamentals and applications

Polyphosphates are important but neglected polyelectrolytes that play a major role in biology and in surface science for the stabilization of colloids against flocculation and for the preservation of food. They are also known as “Calgon” ® and intensively used as additives in washing powders. This review aims to review recent developments in which linear polyphosphates are used for the design of new functional coatings using sol–gel processes and layer-by-layer deposition methods. All these methods rely on the high charge density of polyphosphates as inorganic polyelectrolytes, therefore the structure and properties of these molecules are also reviewed. New perspectives will also been given for the design of stimuli responsive coatings at the tiny frontier between biology and materials science.     

STUDY ON PHOTODYNAMIC AND PHOTORESPONSIVE AZO POLYELECTROLYTES*

Several kinds of novel azobenzene-containing polyelectrolytes with special molecular design have been developedfrom acryloyl chloride or epoxy based precursor polymers. The acryloyl chloride based precursor polymer, poly(acryloylchloride), was prepared by free radical polymerization of acryloyl chloride. The azo polyelectrolytes were prepared by anesterification reaction between the precursor polymer and corresponding azo chromophores containing a reactive hydroxylgroup, followed by hydrolysis of the unreacted acyl chloride groups. The epoxy based precursor polymer was prepared by thereaction between 1,4-cyclohexanedimethanol diglycidyl ether and aniline, and postfunctionalized by azo coupling reaction toform azo polymers containing chromophores with ionizable groups. The polyelectrolytes were characterized by elementalanalysis, ~1H-NMR, IR and UV-Vis spectroscopy. The photodynamic and photoresponsive properties, as well as self-assemblyof these azo polyelectrolytes are reported in this paperp.     

有机半导体荧光传感材料及危险化学品检测应用

荧光传感材料作为有机半导体光电功能材料的重要组成之一,以其灵敏度高、选择性强、响应速度快等优势,成为当前化学传感领域的一个研究热点,近年来在反恐、禁毒等领域有着广泛的应用.然而目前,对荧光敏感材料各项性能参数的设计与优化,依然存在着经验性问题,需要基于构效结合思维,从待测物质的分子层次的物性认知出发,更有针对性地设计相应的传感材料.本文基于国内外前沿工作,结合本课题组多年在危险化学品荧光传感方向的经验,以爆炸物、神经毒剂和合成毒品的检测为例,对荧光敏感材料的设计原则和传感的分子级微观作用机制进行了系统论述.     

Synthesis of thiophene/phenylene co‐oligomers. III . thienyl‐capped oligophenylenes

The author reports the synthesis of thienyl‐capped oligophenylenes via improved synthetic schemes. These schemes are based on either the Grignard or Suzuki coupling reaction and enable the author to obtain the target compounds at appreciably high yields. Regarding several of these compounds, their synthesis and characterization are believed to be reported for the first time. The resulting materials have been fully characterized through the nmr and ir spectroscopy. The ir analysis is particularly useful in characterizing the materials of higher molecular weight, since those materials are difficult to dissolve in organic solvents.     

Water soluble photoactive cellulose derivatives: synthesis and characterization of mixed 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetic acid–(3-carboxypropyl)trimethylammonium chloride esters of cellulose

Photoactive derivatives of cellulose were prepared by a mild esterification of the biopolymer with 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetic acid via the activation of the carboxylic acid with N,N′-carbonyldiimidazole. Subsequently, modification with the cationic carboxylic acid (3-carboxypropyl)trimethylammonium chloride was carried out. Thus, water soluble polyelectrolytes decorated with high amounts of photochemically active chromene moieties were obtained. The structures of the novel polysaccharide esters and the polyelectrolytes were evaluated by means of NMR and IR spectroscopy. Moreover, the light triggered photodimerization of the chromene moieties of the photoactive polyelectrolytes was studied by means of UV–Vis spectroscopy in the dissolved state. The photochemistry observed may be used to control the properties of the new polysaccharide derivatives and are thus of interest in the design of smart materials.     

“Chimie douce”: A land of opportunities for the designed construction of functional inorganic and hybrid organic-inorganic nanomaterials

“Chimie douce” based strategies allow, through the deep knowledge of materials chemistry and processing, the birth of the molecular engineering of nanomaterials. This feature article will highlight some of the main research accomplishments we have performed during the last years. We describe successively the design and properties of: sol–gel derived hybrids, Nano Building Blocks (NBBs) based hybrid materials, nanostructured porous materials proceeds as thin films and ultra-thin films, aerosol processed mesoporous powders and finally hierarchically structured materials. The importance of the control of the hybrid interfaces via the use of modern tools as DOSY NMR, SAXS, WAXS, Ellipsometry that are very useful to evaluate in situ the hybrid interfaces and the self-assembly processes is emphasized. Some examples of the optical, photocatalytic, electrochemical and mechanical properties of the resulting inorganic or hybrid nanomaterials are also presented.     

Progress of Indeno-type Organic Diradicaloids

Organic diradicaloids have unusual open-shell nature and properties and are promising materials for organic electronics, spintronics, energy storage and nonlinear optics. In this review, we focus on indeno-type organic diradicaloids and summarize their molecular design and synthesis, as well as topological structures, open-shell characters and diradical properties. The molecular systems are classified into indenofluorenes and diindenoacenes, indeno-based molecules with one-dimensional, two-dimensional and unique topological structures, and heterocyclic indeno-based molecules. By constructing these various topological π-skeletons with tunable conjugation modes and variation of atomic composition, their key open-shell parameters, such as diradical characters and singlet-triplet energy gaps, along with the optical, electronic and magnetic properties, as well as stabilities are efficiently modulated. More attention may be paid to accurate computational analysis, rational design and synthesis, and novel functions of indeno-type diradicaloids, which will promote the development of radical chemistry and materials.     

Ionically crosslinked polyelectrolyte nanocarriers: Recent advances and open problems

Over the past two decades, nanocarriers prepared through ionic crosslinking of polyelectrolytes have been explored in a wide range of applications, including drug delivery, medical imaging and food science. The design and use of these materials require control over their size distributions, stability, and payload uptake and release properties. To this end, we focus on recent progress made towards understanding the physical and colloid chemistry underlying the formation and properties of ionically crosslinked nanocarriers and provide commentary on some unresolved problems.     

Charge transfer in and conductivity of molecularly doped thiophene‐based copolymers

The electrical conductivity of organic semiconductors can be enhanced by orders of magnitude via doping with strong molecular electron acceptors or donors. Ground‐state integer charge transfer and charge‐transfer complex formation between organic semiconductors and molecular dopants have been suggested as the microscopic mechanisms causing these profound changes in electrical materials properties. Here, we study charge‐transfer interactions between the common molecular p‐dopant 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane and a systematic series of thiophene‐based copolymers by a combination of spectroscopic techniques and electrical measurements. Subtle variations in chemical structure are seen to significantly impact the nature of the charge‐transfer species and the efficiency of the doping process, underlining the need for a more detailed understanding of the microscopic doping mechanism in organic semiconductors to reliably guide targeted chemical design. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 58–63     

Hierarchically Structured Porous Films of Silica Hollow Spheres via Layer‐by‐Layer Assembly and Their Superhydrophilic and Antifogging Properties

Raspberrylike organic/inorganic composite spheres are prepared by stepwise electrostatic assembly of polyelectrolytes and silica nanoparticles onto monodisperse polystyrene spheres. Hierarchically structured porous films of silica hollow spheres are fabricated from these composite spheres by layer‐by‐layer assembly with polyelectrolytes followed by calcination. The morphologies of the raspberrylike organic/inorganic composite spheres and the derived hierarchically structured porous films are observed by scanning and transmission electron microscopy. The surface properties of these films are investigated by measuring their water contact angles, water‐spreading speed, and antifogging properties. The results show that such hierarchically structured porous films of silica hollow spheres have unique superhydrophilic and antifogging properties. Finally, the formation mechanism of these nanostructures and property–structure relationships are discussed in detail on the basis of experimental observations.     

Functional Organic Semiconductors Based on Bay‐Annulated Indigo (BAI)

The advancement of organic electronics has been continually pushed by the need for stable and high performance acceptor materials. By utilizing inexpensive and stable indigo dye as a starting material, Bay‐Annulated Indigo (BAI) provides a new motif for the development of semiconducting materials. Modular and straightforward synthesis makes BAI an outstanding platform for molecular design, while excellent stability, strong absorption, and high ambipolar mobility render BAI‐based materials excellent candidates for organic electronics. BAI‐based polymers and small molecules have taken advantage of these properties to show promising results in a variety of applications.     

Manipulation of molecular transport into mesoporous silica thin films by the infiltration of polyelectrolytes

The design of hybrid mesoporous materials incorporating polymeric assemblies as versatile functional units has become a very fertile research area offering major opportunities for controlling molecular transport through interfaces. However, the creation of such functional materials depends critically on our ability to assemble polymeric units in a predictable manner within mesopores with dimensions comparable to the size of the macromolecular blocks themselves. In this work, we describe for the first time the manipulation of the molecular transport properties of mesoporous silica thin films by the direct infiltration of polyelectrolytes into the inner environment of the 3D porous framework. The hybrid architectures were built up through the infiltration-electrostatic assembly of polyallylamine (PAH) on the mesopore silica walls, and the resulting systems were studied by a combination of experimental techniques including ellipso-porosimetry, cyclic voltammetry and X-ray photoelectron spectroscopy, among others. Our results show that the infiltration-assembly of PAH alters the intrinsic cation-permselective properties of mesoporous silica films, rendering them ion-permeable mesochannels and enabling the unrestricted diffusion of cationic and anionic species through the hybrid interfacial architecture. Contrary to what happens during the electrostatic assembly of PAH on planar silica films (quantitative charge reversal), the surface charge of the mesoporous walls is completely neutralized upon assembling the cationic PAH layer (i.e., no charge reversal occurs). We consider this work to have profound implications not only on the molecular design of multifunctional mesoporous thin films but also on understanding the predominant role of nanoconfinement effects in dictating the functional properties of polymer-inorganic hybrid nanomaterials.     

Topochemical Polymerization of 1,3‐Diene Monomers and Features of Polymer Crystals as Organic Intercalation Materials

From the viewpoint of controlled polymer synthesis, topochemical polymerization based on crystal engineering is very useful for controlling not only the primary chain structures but also the higher‐order structures of the crystalline polymers. We found a new type of topochemical polymerization of muconic and sorbic acid derivatives to give stereoregular and high‐molecular weight polymers under photo‐, X‐ray, and γ‐ray irradiation of the monomer crystals. In this article, we describe detailed features and the mechanism of the topochemical polymerization of diethyl‐(Z,Z)‐muconate as well as of various alkylammonium derivatives of muconic and sorbic acids, which are 1,3‐diene mono‐ and dicarboxylic acid derivatives, to control the stereochemical structures of the polymers. The polymerization reactivity of these monomers in the crystalline state and the stereochemical structure of the polymers produced are discussed based on the concept of crystal engineering, which is a useful method to design and control the reactivity, structure, and properties of organic solids. The reactivity of the topochemical polymerization is determined by the monomer crystal structure, i.e. the monomer molecular arrangement in the crystals. Polymer crystals derived from topochemical polymerization have a high potential as new organic crystalline materials for various applications. Organic intercalation using the polymer crystals prepared from alkylammonium muconates and sorbates is also described.     

Redox-responsive carbometalated ruthenium and osmium complexes

Organometallic conjugated complexes have become an important type of stimuli-responsive materials because of their appealing electrochemical properties and rich photonic, electronic, and magnetic properties. They are potentially useful in a wide range of applications such as molecular wires, molecular switches, molecular machines, molecular memory, and optoelectronic detections. This review outlines the recent progress on the molecular design of carbometalated ruthenium and osmium complexes and their applications as redox-responsive materials with visible and near-infrared (NIR) absorptions and electron paramagnetic resonance as readout signals. Three molecule systems are introduced, including the symmetric diruthenium complexes, metal-amine conjugated bi-center system, and multi-center redox-active organometallic compounds. Because of the presence of a metal-carbon bond on each metal component and strong electronic coupling between redox sites, these compounds display multiple reversible redox processes at low potentials and each redox state possesses significantly different physical and chemical properties. Using electrochemical potentials as input signals, these materials show reversible NIR absorption spectral changes, making them potentially useful in NIR electrochromism and information storage.     

Of Twists and Curves: Electronics,Photophysics, and Upcoming Applications of Non-Planar Conjugated Organic Molecules

Non-planar conjugated organic molecules (NPCOMs) contain π-conjugation across their length and also exhibit asymmetry in their conformation. In other words, certain molecular fragments in NPCOMs are either twisted or curved out of planarity. This conformational asymmetry in NPCOMs leads to non-uniform charge-distribution across the molecule, with important photophysical and electronic consequences such as altered thermodynamic stability, chemical reactivity, as well as materials properties. Majorly, NPCOMs can be classified as having either Fused or Rotatable architectures. NPCOMs have been the focus of significant scientific attention in the recent past due to their exciting photophysical behavior that includes intramolecular charge-transfer (ICT), thermally activated delayed fluorescence (TADF) and long-lived charge-separated states. In addition, they also have many useful materials characteristics such as biradical character, semi-conductivity, dynamic conformations, and mechanochromism. As a result, rational design of NPCOMs and mapping their structure-property correlations has become imperative. Researchers have executed conformational changes in NPCOMs through a variety of external stimuli such as pH, temperature, anions-cations, solvent, electric potential, and mechanical force in order to tailor their photophysical, optoelectronic and magnetic properties. Converging to these points, this review highlights the lucrative electronic features, photophysical traits and upcoming applications of NPCOMs by a selective survey of the recent scientific literature.     

Design and Synthesis of Conjugated Starburst Molecules for Optoelectronic Applications

In recent years, conjugated starburst molecules, which possess a core unit with radial arms linked to the central axle, have become the research topic owing to their well‐defined chemical structures, good solution processability, excellent reproducibility, and superior optoelectronic properties. The increasing interest in starburst systems is evidenced by progressively more frequent investigation on the use of these materials in optoelectronics. The ability to modify chemical structures through control over the core and arms on a molecular level can directly affect the electronic and electroluminescent characteristics of the resulting materials. In this review, we summarize and discuss main progress in our group concerning the rapidly developing field, in which strategies for the design and construction of starbursts are presented at length. Moreover, their application in organic light‐emitting diodes (OLEDs) and organic semiconductor lasers (OSLs) are demonstrated as well, exploring the influence of molecular structures on the optoelectronic properties. Challenges and outlooks are also given at last.     

The combination of ionic surfactants with polyelectrolytes-a new material for membranes?

The combination of two oppositely charged polyelectrolytes results in polyelectrolyte complexes. The simultaneous interfacial reaction between the different polyions leads to formation of polyelectrolyte complex membranes. Some of these have a very good performance in the membrane process pervaporation, especially for dehydration of organic liquids. The combination of a polyelectrolyte with an ionic surfactant of opposite charge results like-wise membranes but with other separation properties. The differences between the two types of membranes, formed from cellulosesulfate in combination with cationic polyelectrolytes or cationic surfactants, will be discussed.