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The development of new polymer materials is an emerging field for more than 100 years. However, it is currently facing major challenges and the application of digital methods can help to develop new processes, discover new materials and, thus, contribute to the challenges of today and the future. Though, the application of digital methods in the field of polymer science is currently very limited, when compared to other classes of materials such as small molecules or inorganic high‐performance materials. Nevertheless, there are already first, very promising approaches. The current review article focuses on the application of these methods in different aspects of polymer research including polymer design, synthesis, and characterization. Furthermore, the digital discovery of polymer engineering is highlighted in detail showing the broad range of potential applications of these methods in polymer science. Finally, future possibilities and opportunities are derived from the current state‐of‐the‐art and perspectives for a potential evolution of polymer science are provided. [ABSTRACT FROM AUTHOR]

Materials chemistry and self‐assembly properties are usually treated separately, largely limiting the real‐time control of their nanostructures and resulting macroscopic properties in advanced self‐assembled materials. This study shows a model system that integrates synthesis and self‐assembly to achieve controlled periodicity and photonic properties in block copolymers (BCPs) at defined locations. First, the BCP thin films containing a pre‐dissolved photo‐initiator are swollen with monomer vapors. Upon exposure to UV light, the photoreaction synthesizes homopolymers within the film, which simultaneously blend with the BCPs and modify the periodicity in the exposed regions. This technique is successfully adapted to cylindrical polystyrene‐b‐polyisoprene‐b‐polystyrene and lamellar polystyrene‐b‐poly(2‐vinyl pyridine) BCP thin films. This capability is especially useful in the practical application of photonic crystals, where it is shown that the stop band position of polystyrene‐b‐quaternized‐poly(2‐vinyl pyridine) photonic gel films can be successfully modulated in situ. A large‐scale pattern is then fabricated by using a photomask. This study provides a model system for integrating materials synthesis and self‐assembly to achieve spatially defined control over structural periodicity and macroscopic properties in self‐assembled materials. [ABSTRACT FROM AUTHOR]

Autoimmune diseases are a group of debilitating illnesses that are often idiopathic in nature. The steady rise in the prevalence of these conditions warrants new approaches for diagnosis and treatment. Stimuli‐responsive biomaterials also known as "smart," "intelligent," or "recognitive" biomaterials are widely studied for their applications in drug delivery, biosensing, and tissue engineering due to their ability to produce thermal, optical, chemical, or structural changes upon interacting with the biological environment. Studies within the last decade that harness the recognitive capabilities of these biomaterials toward the development of novel detection and treatment options for autoimmune diseases are critically analyzed. [ABSTRACT FROM AUTHOR]

Oral vaccines have the potential to reduce cost, improve compliance, and induce immunity at mucosal surfaces that are the first line of defense against infection. The gastrointestinal tract is highly evolved to efficiently digest and absorb nutrients without eliciting aberrant inflammation. However, these functions also limit the efficacy of immunization by the oral route. While mechanisms responsible for the development of tolerance to fed antigens are being illuminated, the application of materials with precise physiochemical properties and immunomodulatory potential may accelerate understanding of immunity within the gastrointestinal tract. Insight into these immunological mechanisms can inform the design of next‐generation oral vaccines to harness critical functions to elicit immunity. Here, material strategies for oral vaccines and their dual function in understanding and overcoming immunological barriers associated with oral immunization are discussed. [ABSTRACT FROM AUTHOR]

Classical microcontact printing and polymer pen lithography (PPL) involve ink transfer to substrates using solid elastomeric stamps. Ink depletion thus limits the number of successive stamping steps without reinking. Porous stamps developed to overcome this limitation are used only for manual proof‐of‐principle experiments. Here, porous composite stamps for scanner‐based capillary stamping (SCS) that can be mounted on automated printing devices designed for PPL are developed. Porous SCS composite stamps consist of a rigid controlled porous silica glass (CPG) layer and a porous polymeric stamping layer. The latter can be topographically structured with contact elements by replication molding. The mechanical stabilization by the CPG layer ensures that the contact elements are coplanar. SCS allows automated, continuous, high‐throughput patterning enabled by ink supply through the porous SCS composite stamps. Even after more than 800 consecutive stamp–substrate contacts without reinking (the porous SCS composite stamps themselves are used as ink reservoirs), ink microdroplets are deposited without deterioration of the pattern quality. However, SCS also allows supply of additional ink during ongoing stamping operations through the pore systems of the porous SCS composite stamps. SCS can easily be adapted for multi‐ink patterning and may pave the way for further upscaling of contact lithography. [ABSTRACT FROM AUTHOR]

Abstract: The combined effects of illumination and thermal annealing on the morphological stability and photodimerization in polymer/fullerene thin films are examined. While illumination is known to cause fullerene dimerization and thermal stress their dedimerization, the operation of solar cells involves exposure to both. The competitive outcome of these factors with blends of phenyl‐C61‐butyric acid methyl ester (PCBM) and polystyrene (PS), supported on PEDOT:PSS is quantified. UV–vis spectroscopy is employed to quantify dimerization, time‐resolved neutron reflectivity to resolve the vertical composition stratification, and atomic force microscopy for demixing and coarsening in thin films. At the conventional thermal stress test temperature of 85 °C (and even up to the PS glass transition), photodimerization dominates, resulting in relative morphological stability. Prior illumination is found to result in improved stability upon high temperature annealing, compatible with the need for dedimerization to occur prior to structural relaxation. Modeling of the PCBM surface segregation data suggests that only PCBM monomers are able to diffuse and that illumination provides an effective means to control dimer population, and thus immobile fullerene fraction, in the timescales probed. The results provide a framework for understanding of the stability of organic solar cells under operating conditions. [ABSTRACT FROM AUTHOR]

Abstract: The selective removal of structural elements plays a decisive role in 3D printing applications enabling complex geometries. To date, the fabrication of complex structures on the microscale is severely limited by multistep processes. Herein, a subtractive photoresist platform technology that is transferable from microscopic 3D printing via direct laser writing to macroscopic structures via stereolithography is reported. All resist components are readily accessible and exchangeable, offering fast adaptation of the resist's property profile. The micro‐ and macroprinted structures can be removed in a facile fashion, without affecting objects based on standard photoresists. The cleavage is analyzed by time‐lapse optical microscopy as well as via in‐depth spectroscopic assessment. The mechanical properties of the printed materials are investigated by nanoindentation. Critically, the power of the subtractive resist platform is demonstrated by constructing complex 3D objects with flying features on the microscale. [ABSTRACT FROM AUTHOR]

Abstract: The numerous potential benefits of incorporating anion‐exchange membranes (AEMs), in place of proton‐exchange membranes (PEMs), in energy storage and conversion technologies renders their development of fundamental importance for the continued evolution of alternative energy systems. However, the widespread implementation of AEMs is currently plagued by a range of problems including lower conductivity (with respect to PEMs), poor stability, and high cost. This study reports the conversion of polyketone, one of the world's most mass produced and cheap polymers, to a new highly tuneable polymer architecture, functionalized polyketone (FPK), that demonstrates a range of excellent properties rendering it a significant prospect for AEM materials. The thermal, processing, and ion‐conducting properties of FPK are governed by the amount and nature of the newly formed N‐substituted pyrrole pendant side groups. At 80 °C, the quarternized pyridyl FPK derivative (4MPyrFPK) yields ion‐conductivities of 8.6 and 10.5 mS cm−1 in the iodide and hydroxide forms. In addition, the hydroxide form of 4MPyr‐FPK demonstrates remarkable stability toward the typically problematic alkaline conditions. No chemical decomposition is observed to the membrane after imbibing it in KOH solution for 72 h, and furthermore, the ion‐conductivity is demonstrated to remain constant for at least 30 d at 80 °C. [ABSTRACT FROM AUTHOR]

Abstract: The use of adhesives for fracture fixation can revolutionize the surgical procedures toward more personalized bone repairs. However, there are still no commercially available adhesive solutions mainly due to the lack of biocompatibility, poor adhesive strength, or inadequate fixation protocols. Here, a surgically realizable adhesive system capitalizing on visible light thiol–ene coupling chemistry is presented. The adhesives are carefully designed and formulated from a novel class of chemical constituents influenced by dental resin composites and self‐etch primers. Validation of the adhesive strength is conducted on wet bone substrates and accomplished via fiber‐reinforced adhesive patch (FRAP) methodology. The results unravel, for the first time, on the promise of a thiol–ene adhesive with an unprecedented shear bond strength of 9.0 MPa and that surpasses, by 55%, the commercially available acrylate dental adhesive system Clearfil SE Bond of 5.8 MPa. Preclinical validation of FRAPs on rat femur fracture models details good adhesion to the bone throughout the healing process, and are found biocompatible not giving rise to any inflammatory response. Remarkably, the FRAPs are found to withstand loads up to 70 N for 1000 cycles on porcine metacarpal fractures outperforming clinically used K‐wires and match metal plates and screw implants. [ABSTRACT FROM AUTHOR]

Abstract: Critical considerations in engineering biomaterials for rotator cuff repair include bone‐tendon‐like mechanical properties to support physiological loading and biophysicochemical attributes that stabilize the repair site over the long‐term. In this study, UV‐crosslinkable polyurethane based on quadrol (Q), hexamethylene diisocyante (H), and methacrylic anhydride (M; QHM polymers), which are free of solvent, catalyst, and photoinitiator, is developed. Mechanical characterization studies demonstrate that QHM polymers possesses phototunable bone‐ and tendon‐like tensile and compressive properties (12–74 MPa tensile strength, 0.6–2.7 GPa tensile modulus, 58–121 MPa compressive strength, and 1.5–3.0 GPa compressive modulus), including the capability to withstand 10 000 cycles of physiological tensile loading and reduce stress concentrations via stiffness gradients. Biophysicochemical studies demonstrate that QHM polymers have clinically favorable attributes vital to rotator cuff repair stability, including slow degradation profiles (5–30% mass loss after 8 weeks) with little‐to‐no cytotoxicity in vitro, exceptional suture retention ex vivo (2.79–3.56‐fold less suture migration relative to a clinically available graft), and competent tensile properties (similar ultimate load but higher normalized tensile stiffness relative to a clinically available graft) as well as good biocompatibility for augmenting rat supraspinatus tendon repair in vivo. This work demonstrates functionally graded, bone‐tendon‐like biomaterials for interfacial tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: Organic getters are used to reduce the amount of reactive hydrogen in applications such as nuclear plants and transuranic waste. The present study examines the performance of getter loaded silicone elastomers in reducing reactive hydrogen gas from the gas phase and their capability of being 3D printed using direct ink writing techniques. The samples are placed in closed vessels and exposed to hydrogen atmosphere at pressures of 580 torr and 750 mtorr and at a temperature of 25 °C. The hydrogen consumption is measured as a function of time and normalized to getter concentration in the polymer. The performance of the getter‐loaded silicone elastomer containing 1,4‐bis[phenylethynyl]benzene (DEB) as the organic getter and Pd/C catalyst (ratio of 3:1 DEB to catalyst) decreases with increasing the resin's curing temperature. Chemical analysis suggests that DEB reacts with the silicone resin at high temperatures. In addition, it is demonstrated that the increased surface area of 3D printed composites results in improved getter performance. [ABSTRACT FROM AUTHOR]

Abstract: Semiconducting single‐walled carbon nanotubes (sc‐SWCNTs) enriched by a conjugated polymer extraction process have been actively studied for various applications in both electronics and optoelectronics. Although the resulting tube samples usually have high sc‐purity and concentration, SWCNT networks from such dispersions typically contain residual conjugated polymer that may degrade device performance and its removal remains a challenge while maintaining uniform, dense SWCNT thin film networks. In this study, a novel polymer–SWCNT combination based on an alternating bisfuran‐s‐tetrazine and benzo[1,2‐b:4,5‐b′]dithiophene copolymer abbreviated as PBDTFTz is proposed. This polymer decomposes at >250 °C or under UV irradiation. In situ transistor characterization under laser irradiation confirms the polymer decomposition. The study of the tube network in the transistor channel at various channel lengths reveals significantly reduced contact resistance attributed to removal of the wrapping PBDTFTz polymer. In ammonia sensing experiments, sc‐SWCNT networks demonstrate rapid and reversible responses, while the unwrapped nanotube networks prove superior in terms of signal to noise ratio and a detection limit of 2.5 ppb is calculated, almost four times better than polymer wrapped nanotubes. [ABSTRACT FROM AUTHOR]

Delivering stem/progenitor cells via a degradable synthetic membrane to devitalized allogenic tissue graft surfaces presents a promising allograft-mediated tissue regeneration strategy. However, balancing degradability and bioactivity of the synthetic membrane with physical characteristics demanded for successful clinical translation is challenging. Here, well-integrated composites of hydroxyapatite (HA) and amphiphilic poly(lactide- co-glycolide)- b-poly(ethylene glycol)- b-poly(lactide- co-glycolide) (PELGA) with tunable degradation rates are designed that stiffen upon hydration and exhibit excellent shape recovery ability at body temperature for efficiently delivering skeletal progenitor cells around bone grafts. Unlike conventional degradable polymers that weaken upon wetting, these amphiphilic composites stiffen upon hydration as a result of enhanced polyethylene glycol (PEG) crystallization. HA-PELGA composite membranes support the attachment, proliferation, and osteogenesis of rat periosteum-derived cells in vitro, as well as the facile transfer of confluent cell sheets of green fluorescent protein-labeled bone marrow stromal cells. With efficient shape memory behaviors around physiological temperature, the composite membranes can be programmed with a permanent tubular configuration, deformed into a flat temporary shape desired for cell seeding/cell sheet transfer, and triggered to wrap around a femoral bone allograft upon 37 °C saline rinse and subsequently stiffen. These properties combined make electrospun HA-PELGA promising smart synthetic periosteal membranes for augmenting allograft healing. [ABSTRACT FROM AUTHOR]

Biologically derived organic molecules are a cost-effective and environmentally benign alternative to the widely used metal-based electrodes employed in current energy storage technologies. Here, the first bio-derived pendant polymer cathode for lithium-ion batteries is reported. The redox moiety is flavin and is derived from riboflavin (vitamin B2). A semi-synthetic methodology is used to prepare the pendant polymer, which is composed of a poly(norbornene) backbone and pendant flavin units. This semi-synthetic approach reduces the number of chemical transformations required to form this new functional material. Lithium-ion batteries incorporating this polymer have a 125 mAh g−1 capacity and an ≈2.5 V operating potential. It is found that charge transport is greatly improved by forming hierarchical structures of the polymer with carbon black, and new insight into electrode degradation mechanisms is provided which should be applicable to polymer electrodes in general. This work provides a foundation for the use of bio-derived pendant polymers in sustainable, high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

All-optical deformation and recovery of complex topographical features is demonstrated within elastic sheets composed of main-chain type azobenzene-functionalized liquid crystalline elastomers (azo-LCEs). The azo-LCEs are synthesized via an orthogonal, two-step reaction between commercially available LC monomers and n-butylamine. By employing surface alignment, the local orientation of the nematic director is spatially complex ('blueprinted'). Exposing the blueprinted LCE films to light as an actinic stimulus generates a photomechanical response which yields reversible shape changes between 2D and 3D shapes. The deformation of azo-LCEs strongly depends on the azobenzene concentration as well as the network structure (i.e., crosslink density). Blueprinting complex director profiles within azo-LCEs yield reconfigurable elastic sheets that can be addressed both remotely and selectively which may have benefit in a variety of applications in aerospace, medicine, and optics. [ABSTRACT FROM AUTHOR]

A series of photoresponsive and full-colored fluorescent conjugated copolymers is synthesized by combining phenylene- and thienylene-based main chains with photochromic dithienylethene (DE) side chains. Solutions and cast films of the polymers exhibit various colored fluorescence in visible wavelengths of 400−700 nm corresponding to emissions of the conjugated main chain. The fluorescence is reversibly photoswitched between emission and quenching through DE photoisomerization using external stimuli from ultraviolet and visible light irradiation. The reprecipitation method with ultrasonication enables the polymers to form spherical aggregates with diameters of 20−70 nm in water. After investigating and comparing the optical properties, the resulting nanosphere solutions are assumed to exist in an intermediate state between an isolated state (i.e., in solution) and an aggregated state in cast film. The majority of the nanosphere solutions also exhibit the same photoswitchable fluorescence behavior as those in the solutions and the cast films. The results demonstrate that the visible fluorescence of the conjugated copolymers is reversibly switchable between emission and quenching using the photoisomerizing DE side chain regardless of the fluorescent colors and the polymer chain aggregation. [ABSTRACT FROM AUTHOR]

Ultralight polymer sponges are prepared by freeze-drying of dispersions of short electrospun fibers. In contrast to many other highly porous materials, these sponges show extremely low densities (<3 mg cm−3) in combination with low specific surface areas. The resulting hierarchical pore structure of the sponges gives basis for soft and reversibly compressible materials and to hydrophobic behavior in combination with excellent uptake for hydrophobic liquids. Owing to their large porosity, cell culturing is successful after hydrophilic modification of the sponges. [ABSTRACT FROM AUTHOR]

Numerous microencapsulation techniques have been developed to encase various chemicals, for which specific processing parameters are required to address the widely differing features of the encapsulated materials. Microencapsulation of reactive agents is a powerful technique that has been extensively applied to self-healing materials. However, the poor solvent compatibility and insufficient thermal stability of microcapsules continue to pose challenges for long-term storage, processing, and service in practical applications. Here, an easily modifiable and highly versatile method is reported for preparing various chemicals filled poly(urea-formaldehyde) microcapsules that exhibit superior tightness against solvents and heat and that possess widely tunable, repetitiously self-restorable, and solvent-proof superhydrophobicity. In addition, the low-cost fabrication of biomimetic multifunctional smart coatings is demonstrated for self-healing anticorrosion and self-cleaning antifouling applications by directly dispersing the superhydrophobic microcapsules into and onto a polymer matrix. The methodology presented in this study should inspire the development of multifunctional intelligent materials for applications in related fields. [ABSTRACT FROM AUTHOR]

The formation and characterization of a novel class of all-natural digestible microcapsules containing a liquid lipid core encapsulated by a water-insoluble protein shell with tunable thickness is demonstrated. As an example of a water-insoluble protein, zein is used-the protein of corn-which is an attractive biomaterial from a sustainable source. The microcapsules are prepared by a direct and simple method, based on the precipitation of protein from the continuous phase of an oil-in-(water/ethanol) emulsion onto the oil droplets without the need of any surfactant. The shell thickness can be controlled by the amount of precipitated protein. An in vitro digestion assay is performed to study the lipid hydrolysis and biodegradability. The rate of lipid hydrolysis and release of fatty acids are highly dependent on the protein shell thickness. All-natural edible microcapsules with controlled degradation under gastrointestinal conditions can enable new applications for oral delivery systems. They may further be used as a model system for controlled release studies of lipophilic compounds and could promote the sustainable use of underutilized water insoluble proteins as functional biomaterials. [ABSTRACT FROM AUTHOR]

The fabrication of multilayer assemblies from polymeric compounds is an important tool for precise control of film architecture on the nanoscale. In this report, a general, novel approach for the preparation of well-defined polymeric multilayers is described. To achieve this, sulfonyl-azide group containing polymers are first generated and deposited as thin films onto solid (organic) substrates. Upon thermal activation, the system crosslinks and binds to the substrate via C-H bond insertion. Through step-and-repeat procedures, multilayer assemblies are then generated where all the individual layers are linked to each other. As the assembly process does not require any specific molecular interactions, the described process represents a general strategy to generate tailor-made multilayer surface coatings with wide range of film thickness and composition. [ABSTRACT FROM AUTHOR]

Additive manufacturing is a promising technique in tissue engineering, as it enables truly individualized implants to be made to fit a particular defect. As previously shown, a feasible strategy to produce complex multicellular tissues is to deposit different small interfering RNA (siRNA) in porous implants that are subsequently sutured together. In this study, an additive manufacturing strategy to deposit carbohydrate hydrogels containing different siRNAs is applied into an implant, in a spatially controlled manner. When the obtained structures are seeded with mesenchymal stem (stromal) cells, the selected siRNAs are delivered to the cells and induces specific and localized gene silencing. Here, it is demonstrated how to replicate part of a patient's spinal cord from a computed tomography scan, using an additive manufacturing technique to produce an implant with compartmentalized siRNAs in the locations corresponding to distinct tissue. Hydrogel solutions loaded with different siRNA can be co-printed together with polycaprolactone that acts as rigid mechanical support to the hydrogel. This study demonstrates a new route for the production of 3D functionalized, individualized implants which may provide great clinical benefit. [ABSTRACT FROM AUTHOR]

Alternating conjugated polymers of ethylenedioxythiophene and fluorene are prepared using three different synthetic methods to investigate the effects of these synthetic methods on the purity, field-effect transistor (FET) performance, and organic photovoltaic (OPV) performance of the polymer. In this study, microwave-assisted direct arylation polycondensation is used to obtain a high-purity, high-molecular-weight (147 kDa) polymer. This pure polymer exhibits a high FET hole mobility of 1.2 × 10−3 cm2 V−1 s−1 and high OPV performance with a power conversion efficiency of 4%, even though the polymer forms an amorphous film, which absorbs in a limited region of the spectrum. [ABSTRACT FROM AUTHOR]

Here, a novel fabrication technique for integrated organic devices on substrates with complex structure is presented. For this work, free-standing polymeric masks with stencil-patterns are fabricated using an ultra-violet (UV) curable polyurethaneacrylate (PUA) mixture, and used as shadow masks for thermal evaporation. High flexibility and adhesive properties of the free-standing PUA masks ensure conformal contact with various materials such as glass, silicon (Si), and polymer, and thus can also be utilized as patterning masks for solution-based deposition methods, such as spin-coating and drop-casting. Based on this technique, a number of integrated organic transistors are fabricated simultaneously on a cylindrical glass bottle with high curvature, as well as on a flat silicon wafer. It is anticipated that these results will be applied to the development of various integrated organic devices on complex-structured substrates, which can lead to further applications. [ABSTRACT FROM AUTHOR]

Novel biochemically active compact polyelectrolyte complexes (CoPECs) are obtained through a simple coprecipitation and compaction procedure. As shown for the system composed of poly(acrylic acid) (PAA) and poly(allylamine) (PAH) as polyelectrolytes and alkaline phosphatase (ALP) as enzyme, the enzyme can be firmly immobilized into these materials. The ALP not only remains active in these materials, but the matrix also enhances the specific activity of the enzyme while protecting it from deactivation at higher temperature. The presence of the matrix allows fine control and substantial enhancement of reaction rates by varying the salt concentration of the contacting solution or temperature. The excellent reusability, together with the ease of co-immobilizing other useful components, such as magnetic particles, allowing facile handling of the CoPECs, makes these materials interesting candidates for variable scaffolds for the immobilization of enzymes for small- and large-scale enzyme-catalyzed processes. [ABSTRACT FROM AUTHOR]

Nanoscale hybrid dielectrics composed of an ultra-thin polymeric low-κ bottom layer and an ultra-thin high-κ oxide top layer, with high dielectric strength and capacitances up to 0.25 μFcm−2, compatible with low-voltage, low-power, organic electronic circuits are demonstrated. An efficient and reliable fabrication process, with 100% yield achieved on lab-scale arrays, is demonstrated by means of pulsed laser deposition (PLD) for the fast growth of the oxide layer. With this strategy, high capacitance top gate (TG), n-type and p-type organic field effect transistors (OFETs) with high mobility, low leakage currents, and low subthreshold slopes are realized and employed in complementary-like inverters, exhibiting ideal switching for supply voltages as low as 2 V. Importantly, the hybrid double-layer allows for a neat decoupling between the need for a high capacitance, guaranteed by the nanoscale thickness of the double layer, and for an optimized semiconductor-dielectric interface, a crucial point in enabling high mobility OFETs, thanks to the low-κ polymeric dielectric layer in direct contact with the polymer semiconductor. It is shown that such decoupling can be achieved already with a polymer dielectric as thin as 10 nm when the top oxide is deposited by PLD. This paves the way for a very versatile implementation of the proposed approach for the scaling of the operating voltages of TG OFETs with very low level of dielectric leakage currents to the fabrication of low-voltage organic electronics with drastically reduced power consumption. [ABSTRACT FROM AUTHOR]

Naphthalenediimide (NDI)-based polymers co-polymerized with thienyl units are an interesting class of polymer semiconductors because of their good electron mobilities and unique film microstructure. Despite these properties, understanding how the extension of the thienyl co-monomer affects charge transport properties remains unclear. With this goal in mind, we have synthesized a series of NDI derivatives of the parent 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)), which exhibited excellent electron mobility. The strategy comprises both the extension of the donor o-conjugation length and the heteroatomic fusion of the thiophene rings. These newly synthesized compounds are characterized experimentally and theoretically vis-à-vis with P(NDI2OD-T2) as the reference. UV-vis data and cyclic-voltammetry are adopted to assess the effect of the donor modification on the frontier energy levels and on the bandgap. Intra-molecular polaronic effects are accounted for by computing the internal reorganization energy with density functional theory (DFT) calculations. Finally electrons and holes transport is experimentally investigated in field-effect transistors (FETs), by measuring current-voltage characteristics at variable temperatures. Overall we have identified a regime where inter-molecular effects, such as the wavefunction overlap and the degree of energetic disorder, induced by the different donor group prevail over polaronic effects and are the leading factors in determining electrons mobility. [ABSTRACT FROM AUTHOR]

The coupling of the magnetic, electric, and elastic properties in multiferroics creates new collective phenomena and enables next-generation device paradigms. In this work, the hydrogen bonding interaction between hydrate salts and ferroelectric polymers is exploited in the development of high-performance magnetoelectric (ME) polymer laminate composites. The microstructures and crystallite structures of the Al(NO3)3·9H2O doped poly(vinylidene fluoride- co-hexafluoropropylene), P(VDF-HFP), are carefully studied. The effect of hydrogen bonding interaction on the polarization ordering of the ferroelectric polymers is investigated by 2D wide-angle X-ray diffraction, polarized Fourier transform infrared spectra, and dielectric spectra at varied frequencies and temperatures. It is found that hydrogen bond not only promotes the formation of the polar crystallite phase but also improves the polarization ordering in the ferroelectric polymer, which subsequently increases the remnant polarization of the polymers as verified in the polarization-electric field loop measurements. These entail marked improvement in the ME voltage coefficients ( αME) of the resulting polymer laminate composites based on ferromagnetic Metglas relative to analogous composites. The composite exhibits a state-of-the-art αME value of 20 V cm-1 Oe under a dc magnetic field of ≈4 Oe and a colossal αME of 320 V cm-1 Oe at a frequency of 68 kHz. [ABSTRACT FROM AUTHOR]

A new and facile strategy for the development of photonic materials is presented that fufills the conditions of being efficient, stable, and tunable laser emitters over the visible region of spectrum, with the possibility of being easily processable and cost-effective. This approach uses poly(methyl methacrylate) (PMMA) as a host for new dyes with improved efficiency and photostability synthesized. Using a simple protocol, fluorine atoms in the commercial (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) ( F-BODIPY) by carboxylate groups. The new O-BODIPYs exhibit enhanced optical properties and laser behavior both in the liquid and solid phases compared to their commercial analogues. Lasing efficiencies up to 2.6 times higher than those recorded for the commercial dyes are registered with high photostabilities since the laser output remain at 80% of the initial value after 100 000 pump pulses in the same position of the sample at a repetition rate of 30 Hz; the corresponding commercial dye entirely loses its laser action after only 12 000 pump pulses. Distributed feedback laser emission is demonstrated with organic films incorporating new O-BODIPYs deposited onto quartz substrates engraved with appropriated periodical structures. These dyes exhibit laser thresholds up to two times lower than those of the corresponding parent dyes with lasing intensities up to one order of magnitude higher. [ABSTRACT FROM AUTHOR]

Chemisorption of the activated metallocene polymerization catalyst derived from [ rac-ethylenebisindenyl]zirconium dichlororide (EBIZrCl2) on the native Al2O3 surfaces of metallic aluminum nanoparticles, followed by exposure to propylene, affords 0-3 metal-isotactic polypropylene nanocomposites. The microstructures of these nanocomposites are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Electrical measurements show that increasing the concentration of the filler nanoparticles increases the effective permittivity of the nanocomposites to ϵr values as high as 15.4. Because of the high contrast in the complex permittivities and conductivities between the metallic aluminum nanoparticles and the polymeric polypropylene matrix, these composites obey the percolation law for two-phase composites, reaching maximum permittivities just before the percolation threshold volume fraction, vf ≈ 0.16. This unique method of in situ polymerization from the surface of metallic Al particles produces a new class of materials that perform as superior pulse-power capacitors, with low leakage current densities of ≈10−7-10−9 A/cm2 at an applied field of 105 V/cm, low dielectric loss in the 100 Hz-1 MHz frequency range, and recoverable energy storage as high as 14.4 J/cm3. [ABSTRACT FROM AUTHOR]

Injectable materials often have shortcomings in mechanical and drug-eluting properties that are attributable to their high water contents. A water-free, liquid four-armed PEG modified with dopamine end groups is described which changes from liquid to elastic solid by reaction with a small volume of Fe3+ solution. The elastic modulus and degradation times increase with increasing Fe3+ concentrations. Both the free base and the water-soluble form of lidocaine can be dissolved in the PEG4-dopamine and released in a sustained manner from the cross-linked matrix. PEG4-dopamine is retained in the subcutaneous space in vivo for up to 3 weeks with minimal inflammation. This material's tailorable mechanical properties, biocompatibility, ability to incorporate hydrophilic and hydrophobic drugs and release them slowly are desirable traits for drug delivery and other biomedical applications. [ABSTRACT FROM AUTHOR]

The mechanical holdfast of the mussel, the byssus, is processed at acidic pH yet functions at alkaline pH. Byssi are enriched in Fe3+ and catechol-containing proteins, species with chemical interactions that vary widely over the pH range of byssal processing. Currently, the link between pH, Fe3+-catechol reactions, and mechanical function is poorly understood. Herein, it is described how pH influences the mechanical performance of materials formed by reacting synthetic catechol polymers with Fe3+. Processing Fe3+-catechol polymer materials through a mussel-mimetic acidic-to-alkaline pH change leads to mechanically tough materials based on a covalent network fortified by sacrificial Fe3+-catechol coordination bonds. These findings offer the first direct evidence of Fe3+-induced covalent cross-linking of catechol polymers, reveal additional insight into the pH dependence and mechanical role of Fe3+-catechol interactions in mussel byssi, and illustrate the wide range of physical properties accessible in synthetic materials through mimicry of mussel-protein chemistry and processing. [ABSTRACT FROM AUTHOR]

Well defined nanostructured polymeric supramolecular assemblies are formed when an asymmetric perylenebisimide substituted with ethylhexyl chains on one end and functionalized with 3-pentadecylphenol at the other termini ( PDP-UPBI) is complexed with poly(4-vinylpyridine) (P4VP) via a non-covalent specific interaction such as hydrogen-bonding. The resulting P4VP(PDP-UPBI) n complexes are fully solution processable. The bulk structure and morphologies of the supramolecular film studied using small angle and wide angle X-ray scattering reveals highly crystalline nature of the complex. Thin film morphology of the 1:1 complex analyzed using transmission electron microscopy shows uniform lamellar structures in the domain range of 5-10 nm. A clear trend of improved electrical parameters in P4VP(PDP-UPBI) system compared to pristine ( PDP-UPBI) is observed from space charge limited current measurements. In short, a simple and facile method to obtain spatially defined organization of n-type semiconductor perylenebisimide molecules using hydrogen bonding interactions with P4VP as the structural motif is showcased herein. [ABSTRACT FROM AUTHOR]

Durable compact polyelectrolyte complexes (CoPECs) with controlled porosity and mechanical properties are prepared by ultracentrifugation. Because the starting materials, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid sodium salt) (PAA), are weak acids/bases, both composition and morphology are controlled by solution pH. In addition, the nonequilibrium nature of polyelectrolyte complexation can be exploited to provide a range of compositions and porosities under the influence of polyelectrolyte addition order and speed, and concentration. Confocal microscopy shows these 'saloplastic' materials to be highly porous, where pore formation is attributed to a combination of deswelling of the polyelectrolyte matrix and expansion of small inhomogenities by osmotic pressure. The porosity (15-70%) and the pore size (<5 μm to >70 μm) of these materials can be tuned by adjusting the PAA to PAH ratio, the salt concentration, and the pH. The modulus of these CoPECs depends on the ratio of the two polyelectrolytes, with stoichiometric complexes being the stiffest due to optimized charge pairing, which correlates with maximized crosslinking density. Mechanical properties, pore sizes, and pore density of these materials make them well suited to three dimensional supports for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Using the vertical standing wave phenomena commonly regarded as a deterrent in holographic lithography, multifaceted three-dimensional (3D) nanostructures are fabricated on polymeric photoresist materials using a simple two-beam interferometer. Large-area 3D nanostructures with high aspect ratios (greater than 10) are readily produced using this methodology, including grating, pillar and pore patterns. Furthermore, manipulation of the lithography process conditions results in unique sidewall profiles of the nanostructures. Such 3D holographic control even produces highly porous polymer membranes composed of 3D interconnected pore networks, which resembles the 3D photonic crystal compound nanostructures that were previously attainable only with limited pattern coverage area using complex multibeam holographic lithography processes. Such well-tailored high-aspect-ratio 3D nanostructures with large pattern coverage area further enable the fabrication of novel nanostructures for functionalized materials via various additive and subtractive pattern transfer techniques such as etching, deposition, and molding. In particular, direct molding followed by thermal decomposition process leads to the synthesis of hierarchical titanium oxide nanostructures of tunable 3D geometry, which would be of great significance in applications of photonic crystals, photovoltaic solar cells, and photocatalyst in water decontamination. [ABSTRACT FROM AUTHOR]

Two different lithographic techniques for the patterning of thin biopolymer films are developed. The first method is based on using a microstructured elastomeric mold for the structuring of thin films of regenerated cellulose. The thin films are manufactured by spin-coating of trimethylsilyl cellulose (TMSC) and subsequent regeneration. The microchannels formed by the mold and the cellulose film are filled with a cellulase solution by capillary action. In the areas exposed to the enzyme solution, the cellulose film is digested, whereas the area in contact with the mold is protected from the enzymatic activity. Optical thickness measurements, atomic force microscopy and fluorescent staining confirm a successful patterning of cellulose on several substrates by this method. The second method is based on the structured regeneration of thin TMSC films. TMSC surfaces are protected with metal masks and exposed to vapors of hydrochloric acid. These treatments result in hydrophilic cellulose structures surrounded by hydrophobic TMSC with differing physicochemical properties. Treatments of the obtained structures with cellulases allow the selective removal of pure cellulose, whereas a TMSC pattern remains on the surface. These TMSC can be regenerated back to pure cellulose by treatments with vapors of hydrochloric acid. The developed methods allow the effective fabrication of micropatterned biopolymer thin films suitable for further functionalization and application in, e.g., bioanalytical devices. This is shown by the immobilization and detection of single-stranded DNA on structured cellulose surfaces. Owing to the versatility of both patterning approaches the methods can be further extended to other combinations of substrates and enzymes. [ABSTRACT FROM AUTHOR]

Photonic Crystals: Integration of Polymer Synthesis and Self-Assembly for Controlled Periodicity and Photonic Properties (Adv. Funct. Keywords: block copolymers; photonic crystals; polymeric materials; self-assemblies EN block copolymers photonic crystals polymeric materials self-assemblies 1 1 1 01/06/21 20210104 NES 210104 In article number 2005819, Muzhou Wang, Ruimeng Zhang, and Zhe Qiang present an in-film photo-polymerization method to achieve in situ control of periodicity in block copolymer thin films. Block copolymers, photonic crystals, polymeric materials, self-assemblies. [Extracted from the article]

Barriers to therapeutic transport in biological systems can prevent accumulation of drugs at the intended site, thus limiting the therapeutic effect against various diseases. Advances in synthetic chemistry techniques have recently increased the accessibility of complex polymer architectures for drug delivery systems, including branched polymer architectures. This article first outlines drug delivery concepts, and then defines and illustrates all forms of branched polymers including highly branched polymers, hyperbranched polymers, dendrimers, and branched–linear hybrid polymers. Many new types of branched and dendritic polymers continue to be reported; however, there is often confusion about how to accurately describe these complex polymer architectures, particularly in the interdisciplinary field of nanomedicine where not all researchers have in‐depth polymer chemistry backgrounds. In this context, the present review describes and compares different branched polymer architectures and their application in therapeutic delivery in a simple and easy‐to‐understand way, with the aim of appealing to a multidisciplinary audience. [ABSTRACT FROM AUTHOR]

Filler aggregation in polymer matrix nanocomposites leads to inhomogeneity in particle distribution and deterioration of mechanical properties. The use of polymer‐grafted nanoparticles (PGNPs) with polymers directly attached to the particle surfaces precludes aggregation of the filler. However, solids composed of PGNPs are mechanically weak unless the grafted chains are long enough to form entanglements between particles, and requiring long grafts limits the achievable filler density of the nanocomposite. In this work, long, entangled grafts are replaced with short reactive polymers that form covalent crosslinks between particles. Crosslinkable PGNPs, referred to as XNPs, can be easily processed from solution and subsequently cured to yield a highly filled yet mechanically robust composite. In this specific instance, silica nanoparticles are grafted with poly(glycidyl methacrylate), cast into films, and crosslinked with multifunctional amines at elevated temperatures. Indentation and scratch experiments show significant enhancement of hardness, modulus, and scratch resistance compared to non‐crosslinked PGNPs and to crosslinked polymer films without nanoparticle reinforcement. Loadings of up to 57 wt% are achieved while yielding uniform films that deform locally in a predominantly elastic manner. XNPs therefore potentially allow for the formulation of robust nanocomposites with a high level of functionality imparted by the selected filler particles. [ABSTRACT FROM AUTHOR]

Sustainable materials for energy storage are urgently needed due to the increased use of electric vehicles and mobile electronics. On page 6896, D. S. Seferos and co‐workers demonstrate a lithium‐ion battery cathode that consists of a polymer with biologically‐derived pendant groups. Biologically‐derived molecules decrease the cost of the functional material and the environmental impact of the device. [ABSTRACT FROM AUTHOR]

The photoinduced topographical deformation of azobenzene‐functionalized liquid crystalline elastomers is reported by T.J. White and co‐workers on page 5819. The authors report on the use of UV light irradiation to transform originally flat sheets into topographical surfaces. The photoinduced shape transformation and relaxation is shown to strongly depend on the azobenzene concentration as well as the network structure. [ABSTRACT FROM AUTHOR]

Multifunctional superhydrophobic polymeric microcapsules with lotus‐leaf‐like hierarchical surface structure and moisture‐sensitive core are prepared by J. Yang and team on page 6751 by a facile and versatile strategy. The microcapsules exhibit superior shell tightness against solvents and heat, and possess widely tunable, repetitiously self‐restorable, and solvent‐proof superhydrophobicity. By incorporating these microcapsules in coating matrix, a biomimetic smart coating is developed, seamlessly combining self‐healing and self‐cleaning functionalities for anticorrosion and antifouling applications. [ABSTRACT FROM AUTHOR]

A stable, all‐natural, edible, core–shell microcapsule from zein, a protein of corn, and oil is synthesized by E. Filippidi, K. P. Velikov, and colleagues in a one‐step process without the use of any stabilizers or surfactants. On page 5962, the zein shell thickness can be controlled and imparts functionality, controlling the rate of hydrolysis of the encapsulated oil (triacylglycerides). The capsules pass the gastric phase and break down in the intestine. [ABSTRACT FROM AUTHOR]

Nano-sized polymersomes functionalized with peptides or proteins are being increasingly studied for targeted delivery of diagnostic and therapeutic molecules. Earlier computational studies have suggested that ellipsoidal nanoparticles, compared to spherical ones, display enhanced binding efficiency with target cells, but this has not yet been experimentally validated. We hypothesize that hydrophilic polymer chains coupled to vesicle-forming polymers would result in ellipsoidal polymersomes. In addition, ellipsoidal polymersomes modified with cell adhesion peptides bind with target cells more actively than spherical ones. We examine this hypothesis by substituting polyaspartamide with octadecyl chains and varying numbers of poly(ethylene glycol) (PEG) chains. Increasing the degree of substitution of PEG from 0.5 to 1.0 mol% drives the polymer to self-assemble into an ellipsoidal polymersome with an aspect ratio of 2.1. Further modification of these ellipsoidal polymersomes with peptides containing an Arg-Gly-Asp sequence (RGD peptides) lead to a significant increase in the rate of association and decrease in the rate of dissociation with a substrate coated with α v β 3 integrins. In addition, in a circulation-mimicking flow, the ellipsoidal polymersomes linked with RGD peptides adhere to target tissues more favorably than their spherical equivalents do. Overall, the results of this study will greatly serve to improve the efficiency of targeted delivery of a wide array of polymersomes loaded with various biomedical modalities.