Side‐chain functionalized supramolecular polymers

Over the past two decades, the field of supramolecular polymer chemistry has developed from a curiosity to a mature area of polymer science. Among the most promising subjects in this large field are noncovalently functionalized side‐chain polymers that have been investigated extensively as a result of their modular character and ease of synthesis. Side‐chain functionalized polymers have the potential for a profound impact on complex materials. For example, for side‐chain functionalized polymers based on a single noncovalent interaction, materials for a variety of applications ranging from liquid crystalline and electro‐optical materials to drug delivery systems have been reported. Furthermore, materials based on this novel methodology may overcome several shortcomings of current covalent multifunctionalization strategies such as highly complex materials that are extremely difficult or impossible to fabricate with current methods. In this review, basic design requirements, advantages and potential applications are presented. Copyright © 2006 Society of Chemical Industry     

Multiscale thermal modeling of cured cycloaliphatic epoxy/carbon fiber composites

Cycloaliphatic epoxies (CEs) are commonly used for structural applications requiring improved resistance to elevated temperatures, UV radiation, and moisture relative to other epoxy materials. Accurate and efficient computational models can greatly facilitate the development of CE‐based composite materials for applications such as Aluminum Conductor Composite Core high‐voltage power lines. In this study, a new multiscale modeling method is developed for CE resins and composite materials to efficiently predict thermal properties (glass‐transition temperature, thermal expansion coefficient, and thermal conductivity). The predictions are compared to experimental data, and the results indicate that the multiscale modeling method can accurately predict thermal properties for CE‐based materials. For 85% crosslink densities, the predicted glass‐transition temperature, thermal expansion coefficient, and thermal conductivity are 279 °C, 109 ppm °C^?1, 0.24 W m^?1 K^?1, respectively. Thus, this multiscale modeling method can be used for the future development of improved CE composite materials for thermal applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46371.     

Macromolecular and supramolecular chirality: a twist in the polymer tales

Significant advances have been made recently in generating chiral polymer surfaces and materials using a range of methods such as block copolymer self‐assembly, layer‐by‐layer assembly and surface functionalization by polymer brushes. This paves the way for novel chiral materials that can harness and tailor chiral interactions for specific functionalities and properties in a range of biomedical and bioanalytical applications. This paper reviews these advances and speculates on the future of chiral surfaces. © 2013 Society of Chemical Industry     

NIR‐responsive nanomaterials and their applications; upconversion nanoparticles and carbon dots: a perspective

Near‐infrared (NIR) light responsive materials have received much attention for diverse applications due to their excellent optical properties. This type of material exhibits upconverted luminescence, a non‐linear optical process in which two or more low energy photons, usually from NIR light irradiation are transformed to high energy photons emission through energy transfer upconversion, excited state absorption, photon avalanche or multiphoton absorption. The NIR range of excitation source is favorable for biological imaging and cancer theranostic applications due to their high penetration depth, low autofluorescence, minimal light scattering, reduced photodamage, and negligible phototoxicity. Having these properties, NIR responsive materials such as upconversion nanoparticles (UCNPs) and carbon dots (CDs) which perform upconversion luminescence are actively exploited in a wide variety of applications such as display and sensory technology. While CDs are well known for their versatility in using different chemicals and green precursors to achieve tunable optical properties, UCNPs also have the advantage that a continuous‐wave NIR laser can be used as the excitation source. This article reviews the properties of these two materials in the aspects of luminescence mechanisms and their recent developments in cancer theranostics, display technology, biosensing and metal ions sensing applications. © 2018 Society of Chemical Industry     

Ionomer‐based polyurethanes: a comparative study of properties and applications

Polyurethanes cover a large range of materials exhibiting various physical and mechanical properties making them useful in different applications such as elastomers or biomaterials, for instance. The introduction of ionic groups in the polyurethane backbone opens the way to new applications where the ionic groups can act as physical crosslinkers that greatly modify the final mechanical and thermal properties of the materials. Furthermore, the hydrophilicity of the chains can be enhanced by the presence of the ionic species, and so the materials can be processed as conventional dispersions even in a polar solvent such as water. As a consequence the applications are numerous; the main commercial outlets are focused on coatings and textiles industries where they can be used as waterproof coatings or substitutes for leather. But these materials can also be used in high‐tech industries for shape memory materials, biomedical devices and biocompatible materials. This review summarizes the latest developments of this class of promising materials and provides the reader with the potentialities of these polymers in various areas.     

Polyaldehydes: homopolymers,block copolymers and promising applications

This minireview gives a brief overview on the polymerization of higher aldehydes, discusses current applications of certain polyaldehydes, and points toward potential future applications of these interesting materials. Although it was discovered long ago that several aldehydes can be polymerized, the application potential of these polymers was largely overlooked. This is somewhat surprising as many polyaldehydes show interesting properties such as fast and complete depolymerization triggered by chemical or thermal stimuli. Such stimuli‐responsive polymers can be useful materials in many applications in for example nanotechnology or drug delivery. By incorporating polyaldehydes into functional block copolymers even more versatile materials can be created. The increasing number of recent research examples demonstrates the growing interest in polyaldehydes as smart materials and their potential for novel applications. Copyright © 2012 Society of Chemical Industry     

Synthesis of multifunctional high strength,highly swellable,stretchable and self‐healable pH‐responsive ionic double network hydrogels

The multifunctional double network (DN) soft hydrogels reported here are highly swellable and stretchable pH‐responsive smart hydrogel materials with sufficient strength and self‐healing properties. Such multifunctional hydrogels are achieved using double crosslinking structures with multiple physical and chemical crosslinks. They consist of a copolymer network of acrylamide (AM) and sodium acrylate (Na‐AA) and other reversible network of poly(vinyl alcohol)–borax complex. They were characterized by Fourier transform IR analysis and studied for their hydrogen bonding and ionic interaction. The degree of equilibrium swelling was observed to be as high as 5959% (at pH 7.0) for a hydrogel with AM/Na‐AA = 25/75 wt% in the network (GS‐6 sample). The highest degree of swelling was observed to be 6494% at pH 8.5. The maximum tensile strength was measured to be 1670, 580 and 130 kPa for a DN hydrogel (GS‐2 sample: AM/Na‐AA =75/25 wt% with 20, 40 and 60 wt% water content, respectively). The self‐healing efficiency was estimated to be 69% for such a hydrogel. These multifunctional DN hydrogels with amalgamation of many functional properties are unique in hydrogel materials and such materials may find applications in sensors, actuators, smart windows and biomedical applications. © 2018 Society of Chemical Industry     

Solid‐state Materials and Methods for Hydrogen Storage: A Critical Review

Hydrogen is important as a new source of energy for automotive applications. It is clear that the key challenge in developing this technology is hydrogen storage. Current methods for hydrogen storage have yet to meet all the demands for on‐board applications. High‐pressure gas storage or liquefaction cannot fulfill the storage criteria required for on‐board storage. Solid‐state materials have shown potential advantages for hydrogen storage in comparison to other storage methods. In this article, the most popular solid‐state storage materials and methods including carbon based materials, metal hydrides, metal organic frameworks, hollow glass microspheres, capillary arrays, clathrate hydrates, metal nitrides and imides, doped polymer and zeolites, are critically reviewed. The survey shows that most of the materials available with high storage capacity have disadvantages associated with slow kinetics and those materials with fast kinetics have issues with low storage capacity. Most of the chemisorption‐based materials are very expensive and in some cases, the hydrogen absorption/desorption phenomena is irreversible. Furthermore, a very high temperature is required to release the adsorbed hydrogen. On the other hand, the main drawback in the case of physisorption‐based materials and methods is their lower capacity for hydrogen storage, especially under mild operating conditions. To accomplish the requisite goals, extensive research studies are still required to optimize the critical parameters of such systems, including the safety (to be improved), security (to be available for all), cost (to be lowered), storage capacity (to be increased), and the sorption‐desorption kinetics (to be improved).     

Understanding structure and composition of thermally rearranged polymers based on small‐molecule chemistry: a perspective

We provide a critical perspective of the burgeoning literature on microporous polymers prepared using thermal rearrangement (TR) processes based on the learning derived from analogous chemistry involving small‐molecular‐weight compounds. TR polymers have shown interesting permeability–selectivity relationships in gas separation and, thus, have generated wide interest as potential membrane materials for industrial applications. The intractable nature of the products obtained by TR processes has precluded rigorous structural elucidation of the polymers. Based on small‐molecule chemistry, we conclude that structures are likely to be more complex than generally depicted in the published literature. Interestingly, a simpler chemistry, namely thermal dehydrocyclization (TCD), leads to products identical to those derived from TR, but at significantly lower temperatures. However, TCD chemistry does not involve a skeletal rearrangement of the kind purported in TR during the conversion of imide to oxazole ring resulting in spatially confined heterocyclic ring polymers. Yet, they show similar fractional free‐volume elements as exhibited by TR polymers. This is intriguing and points to a need for more careful examination of the factors responsible for microporosity in such materials. TR chemistry as currently practiced appears limited to only benzoxazole‐type structures. The ability to precisely control and reproducibly produce materials with well‐defined structure and properties will be a key to large‐scale manufacture and industrial applications of such materials. Seen from this perspective, TR processes leave much to be desired and further improvements are clearly warranted. © 2019 Society of Chemical Industry     

A review on electrospun polymer nanostructures as advanced bioactive platforms

This review article deals with latest literature studies on the potential use of polymer ultrathin and nanosized structures obtained by electrospinning to design novel engineered materials with bioactive properties. The electrofluidodynamic process offers the option to form high‐performance bioactive systems based on polymer yarns of nanofibers or coatings of nanobeads with high surface‐to‐volume ratios. The electrospun and electrosprayed nanostructures can be further functionalized by encapsulation with bioactive fillers and substances. For both scenarios, the resultant polymer nanostructures present unique bioactive properties capable of providing a beneficial impact over human's health and with improved and advanced performance for biomedicine, pharmaceutics, nutrition, bioengineering, and healthcare applications. These novel functional materials attained by the electrospinning technology can be of interest for many bioactive applications such as functional food design, food packaging, functional coatings, controlled delivery of drug solutions and, mainly, tissue engineering. This article is purposely designed to gather, for the first time, most recent and promising multi‐ and inter‐disciplinary developments based on electrospun systems for bioactive applications, which are either bioactive material concepts or can be advantageously applied to become such. POLYM. ENG. SCI., 56:500–527, 2016. © 2016 Society of Plastics Engineers     

Functional polyelectrolyte multilayer assemblies for surfaces with controlled wetting behavior

Controlled wetting at surfaces and interfaces is an important area of research with numerous potential commercial applications. Both superhydrophobicity and superhydrophilicity can be used to enable applications such as self‐cleaning, dropwise condensation, or antifogging. Many strategies for creating such surfaces center around biomimicry, replicating the structure of the lotus leaf, for example. Given the potential impact, creating surfaces with these properties using any number of fabrication is of great interest. One very promising fabrication technique, however, for creating these surfaces is the layer‐by‐layer (LbL)‐directed self‐assembly of polyelectrolytes and other charged materials. LbL is a sequential adsorption technique wherein a surface is exposed to first a solution of one charge and then a solution of the opposite charge. LbL has many advantages, including the ability to incorporate many different types of materials and therefore functionality, the ability to conformally coat substrates of complex geometry, and environmentally friendly aqueous processing. This review describes recent progress in using LbL to create surfaces with controlled wetting. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42767.     

Trennleistung von Dünnschichtverdampfern

The evaporation process has recently gained new momentum through special applications in chemical engineering and especially in environmental engineering, e.g. in the recovery of materials of value from liquid production residues. Thin‐layer evaporators with rotating wipers are particularly suitable for such tasks if the products of interest are thermally unstable or are prone to crusting. If these applications involve distillation‐type separation then a knowledge of the expected separation effect is important for calculations. This article aims to make a contribution to this topic. It is based on experimental studies performed on a laboratory‐scale thin‐layer evaporator and on earlier treatments of the theory of distillation in thin‐layer evaporators with a mechanically generated liquid film.     

Polymers for medical and tissue engineering applications

Recent decades have seen great advancements in medical research into materials, both natural and synthetic, that facilitate the repair and regeneration of compromised tissues through the delivery and support of cells and/or biomolecules. Biocompatible polymeric materials have become the most heavily investigated materials used for such purposes. Naturally‐occurring and synthetic polymers, including their various composites and blends, have been successful in a range of medical applications, proving to be particularly suitable for tissue engineering (TE) approaches. The increasing advances in polymeric biomaterial research combined with the developments in manufacturing techniques have expanded capabilities in tissue engineering and other medical applications of these materials. This review will present an overview of the major classes of polymeric biomaterials, highlight their key properties, advantages, limitations and discuss their applications. © 2014 Society of Chemical Industry     

Biolubricants: Raw materials,chemical modifications and environmental benefits

The depletion of the world's crude oil reserve, increasing crude oil prices, and issues related to conservation have brought about renewed interest in the use of bio‐based materials. Emphasis on the development of renewable, biodegradable, and environmentally friendly industrial fluids, such as lubricants, has resulted in the widespread use of natural oils and fats for non‐edible purposes. In this study, we have reviewed the available literature and recently published data related to bio‐based raw materials and the chemical modifications of raw materials. Additionally, we have analyzed the impacts and benefits of the use of bio‐based raw materials as functional fluids or biolubricants. The term biolubricants applies to all lubricants, which are both rapidly biodegradable and non‐toxic to humans and other living organisms, especially in aquatic environments. Biodegradability provides an indication of the persistence of the substance in the environment and is the yardstick for assessing the eco‐friendliness of substances. Scientists are discovering economical and safe ways to improve the properties of biolubricants, such as increasing their poor oxidative stability and decreasing high pour points. “Green” biolubricants must be used for all applications where there is an environmental risk.     

Synthese von porösen Voll‐ und Core‐Shell‐Glaskugeln zur Trennung von chiralen Anästhetika

For the separation of chiral anesthetic gases suitable support materials for the selectors are necessary. Due to the controlled texture properties porous glass shows a high potential for such applications. In this study porous glass beads with particle diameters of 40 – 400 µm and 2 – 4 mm could be obtained via a special fluidized‐bed reactor and the method of ionotropic gelation. Furthermore, the first core‐shell beads on the basis of porous glasses could be synthesized via the combination of an ion‐exchange induced phase separation and a selective leaching step. The new materials are characterized by a defined mesoporous shell and a non‐porous glass core.     

Chitin/polyurethane blends: a thermal and morphological study

Chitin is an abundant natural polymer having important properties such as biocompatibility and biodegradability combined with healing capability. Its use in biomedical applications has been hindered by its poor processing properties such as low solubility and stiffness in the solid state. In an attempt to obtain flexible and more processable chitin‐based materials, we prepared blends of the polymer with a polyurethane containing a soft segment based on biodegradable polycaprolactone. A certain degree of miscibility was found between chitin and the polyurethane, as demonstrated by a shift in the glass transition of the polyurethane observed in dynamical mechanical analyses, with a simultaneous decrease in crystallinity of chitin observed in X‐ray diffraction analyses. A phase inversion of the blends took place for a 50/50 (w/w) composition ratio as demonstrated from thermal, dynamic mechanical, tensile and X‐ray diffraction measurements. Blends of chitin with the polycaprolactone‐based polyurethane can be effectively used to produce tough materials useful in biomedical applications. The mechanical strength of the blends demonstrated that they are able to support tensions above those required for bone replacement, making them good candidates for that purpose. Copyright © 2010 Society of Chemical Industry     

Preparation of di‐butyryl‐chitin scaffolds by using salt leaching method for tissue engineering and their characteristics

Scaffolds are used as support material in treatment of damaged tissues such as cartilage and bone. With the help of scaffolds, damaged tissues can be cured in shorter period with less pain. Chitin is one of the most important scaffold materials curing the damaged tissues while providing a support for related part of the body during healing period. It is biocompatible and biodegradable; however it can not be solved by common solvents leading to the major drawback for this kind of applications. Therefore di‐butyril‐chitin (DBC), which is a chitin derivative and can be solved easily in solvents like acetone, ethanol, and methanol, is preferred for scaffold production instead of chitin. In this study, DBC scaffolds were produced for orthopedic applications and their structural and mechanical properties such as porosity, elasticity, compressibility, and strength were tested to confirm their suitability for such end‐uses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cellulose derivatives and graft copolymers as blocks for functional materials

In this review, recent progresses in the synthesis of new cellulose derivatives and graft copolymers are summarized. Cellulose derivatives synthesized in new cellulose solvents, such as ionic liquids and NaOH/urea, and the regioselective synthesis of cellulose derivatives have attracted increasing attention in recent years and could be a more active field for cellulose in the future. Cellulose graft copolymers with well‐defined architectures synthesized by controlled/living radical polymerizations such as atomic transfer radical polymerization and their stimuli‐induced assembly have been investigated extensively. Stimuli‐responsive functional materials can be fabricated using either cellulose derivatives or graft copolymers, and they can be used as biosensors and carriers for controlled delivery of drugs and genes. The fabrication of functional materials with cellulosic blocks and their applications have a bright future. © 2013 Society of Chemical Industry     

Laser ablation of polymers: a review

Laser ablation (LA), which employs a pulsed laser to remove materials from a substrate for generating micro‐/nanostructures, has tremendous applications in the fabrication of metals, ceramics, glasses and polymers. It has become a noteworthy approach for achieving various functional structures in engineering, chemistry, biology, medicine and other fields. Polymers are one such class of materials; they can be melted and vaporized at high temperature during the ablation process. A number of polymers have been researched as candidate substrates in LA, and many different structures and patterns have been realized by this method. The current states of research and progress are reviewed from basic concepts to optimal parameters, polymer types and applications. The significance of this paper is to provide a basis for follow‐up research that leads to the development of superior materials and high‐quality production through LA. In this review, we first introduce the basic concept of LA, including mechanism, laser types (millisecond, microsecond, nanosecond, picosecond and femtosecond) and influential parameters (wavelength, repetition rate, fluence and pulse duration). Then, we focus on several commonly used polymer materials and compare them in detail, including the effects of polymer properties, laser parameters and feature designs. Finally, we summarize the applications of various structures fabricated by LA in a variety of areas along with a perspective of the challenges in this research area. Overall, a thorough review of LA of several polymers is presented, which could pave the way for characterization of future novel materials. © 2019 Society of Chemical Industry     

Nano‐structured materials with low surface energies formed by polyelectrolytes and fluorinated amphiphiles (PEFA)

Polymer complexes formed by polyelectrolytes and fluorinated amphiphiles (PEFA) represent a new class of materials which can be prepared easily as nano‐structured coatings on a large number of chemically different substrates. The surface energies of PEFA coatings are remarkably low and can be adjusted in the range 6–18 m Jm⁻². Many of their physical properties, such as elastic modulus and mechanical strength, are determined by the nature of the polymer structure. By adjusting charge densities, molecular weights and the content of nonionic comonomers, a great variety of optimizations for a number of applications are possible. The amphiphiles have a decisive influence on the nano‐structure and on the surface energy of these materials. They act as building blocks, which vary in their number of fluorinated chains, their chain lengths and in the ionic head‐groups. Carboxylate, phosphate and sulfonate groups are preferred for the preparation of PEFAs. The scope of this review is to present a discussion of the mesomorphous structures (from columnar discotic to perforated lamellar), the low surface energies and attractive applications of these PEFA materials. Applications are found predominantly in low‐friction and anti‐soiling coatings. © 2000 Society of Chemical Industry