Search

Thin-film confinement of self-assembling block polymers results in materials with myriad potential applications—including membranes and optical devices—and provides design parameters for altering phase behavior that are not available in the bulk, namely, film thickness and preferential wetting. However, most research has been limited to lamella- and cylinder-forming polymers; three-dimensional phases, such as double gyroid (DG), have been observed in thin films, but their phase behavior under confinement is not yet well understood. We use self-consistent field theory to predict the equilibrium morphology of bulk-gyroid-forming AB diblock polymers under thin-film confinement. Phase diagrams reveal that the (211) orientation of DG, often observed in experiments, is stable between nonpreferential boundaries at thicknesses as small as 1.2 times the bulk DG lattice parameter. The (001) orientation is stable between modestly B-preferential boundaries, where B is the majority block, while a different (211)-oriented termination plane is stabilized by strongly B-preferential boundaries, neither of which has been observed experimentally. We then describe two particularly important phenomena for explaining the phase behavior of DG thin films at low film thicknesses. The first is "constructive interference," which arises when distortions due to the top and bottom boundaries overlap and is significant for certain DG orientations. The second is a symmetry-dependent, in-plane unit-cell distortion that arises because the distorted morphology near the boundary has a different preferred unit-cell size and shape than the bulk. These results provide a thermodynamic portrait of the phase behavior of DG thin films. [ABSTRACT FROM AUTHOR]

It is highly demanded to understand the confinement effect on nanoconfined polymers. Recent studies reported a strong perturbation of local dynamics and substantial alteration of glass transition temperature Tg at nanoscale. However, how confinement affects the mechanical properties of polymers is not fully understood. Here, we show that the modulus of thin polymer films could be remarkedly altered through a polymer–polymer interface. The modulus of a thin polystyrene (PS) film next to a polydimethylsiloxane (PDMS) was determined from the PS–PDMS bilayer bulging test. A series of experiments show that the modulus of PS can be increased up to 37%, when the modulus of the neighboring PDMS varies from 1.04 to 4.88 MPa. The results demonstrate a strong sensitivity of mechanical properties of thin polymers to the hard/soft environment, which we attribute to the change of high-mobility layer by the polymer–polymer interface. [ABSTRACT FROM AUTHOR]

Thermally stimulated discharge (TSD) technique is a traditional method in dielectric research, especially for electrets. However, in conventional open-circuit and short-circuit TSD techniques, it is difficult to distinguish the surface charge and body charge of dielectric materials. In particular with the test of polymer electrets, the deformation of the polymer film may take place during the measurement process, which will affect the accuracy of the experiment results. In this paper, a glass-assisting TSD (GA-TSD) technique is proposed to solve the above problems. The feasibility of the experimental technique is verified with the GA-TSD spectra of fluorinated ethylene-propylene copolymer electret films. In addition, their theory analysis is also accomplished. The influences of glass thickness, glass dielectric property, and metallizing on the glass on GA-TSD spectra are investigated. The results prove that the GA-TSD spectra can clearly distinguish the difference between surface charge and body charge according to the current direction. The quartz glass with the lowest dielectric constant is best suitable for the GA-TSD technique. The influence of the glass thickness and metallizing on the glass on GA-TSD spectra is little. [ABSTRACT FROM AUTHOR]

Block copolymer self-assembly in conjunction with nonsolvent-induced phase separation (SNIPS) has been increasingly leveraged to fabricate integral-asymmetric membranes. The large number of formulation and processing parameters associated with SNIPS, however, has prevented the reliable construction of high performance membranes. In this study, we apply dynamical self-consistent field theory to model the SNIPS process and investigate the effect of various parameters on the membrane morphology: solvent selectivity, nonsolvent selectivity, initial film composition, and glass transition composition. We examine how solvent selectivity and concentration of polymers in the film impact the structure of micelles that connect to form the membrane matrix. In particular, we find that preserving the order in the surface layer and forming a connection between the supporting and surface layer are nontrivial and sensitive to each parameter studied. The effect of each parameter is discussed, and suggestions are made for successfully fabricating viable block copolymer membranes. [ABSTRACT FROM AUTHOR]

The slow Arrhenius process (SAP) is a dielectric mode connected to thermally activated equilibration mechanisms, allowing for a fast reduction in free energy in liquids and glasses. The SAP, however, is still poorly understood, and so far, this process has mainly been investigated at temperatures above the glass transition. By employing a combination of methods to analyze dielectric measurements under both isochronal and isothermal conditions, we were able to quantitatively reproduce the dielectric response of the SAP of different polymers and to expand the experimental regime over which this process can be observed down to lower temperatures, up to 70 K below the glass transition. Employing thin films of thicknesses varying between 10 and 800 nm, we further verified that the peak shape and activation energy of the SAP of poly(4-bromostyrene) are not sensitive to temperature, nor do they vary upon confinement at the nanoscale level. These observations confirm the preliminary trends reported for other polymers. We find that one single set of parameters—meaning the activation barrier and the pre-exponential factor, respectively, linked to the enthalpic and entropic components of the process—can describe the dynamics of the SAP in both the supercooled liquid and glassy states, in bulk and thin films. These results are discussed in terms of possible molecular origins of the slow Arrhenius process in polymers. [ABSTRACT FROM AUTHOR]

In polymers, the equilibrium state is achieved when the chains have access to the maximum number of conformational states, which allows them to explore a larger conformational space, leading to an increase in the entropy of the system. Preparation of thin polymer films using the spin-coating technique results in polymer chains being locked in a nonequilibrium state with lower entropy due to possible stretching of chains during the process. Allowing enough time for recovery results in the relaxation of the spin-coating-induced molecular recoiling stress. Annealing such a film generates entropy due to its inherent irreversibility. We employed the dewetting technique to determine the molecular recoiling stress relaxation time in poly-(tertbutyl styrene) thin films. Furthermore, we qualitatively differentiated the metastable states achieved by the polymer film using entropy generation in a relaxing polymer film as an effect of thermal entropy and associated it with the conformational entropy of polymer chains utilizing the molecular recoiling stress relaxation time. This enabled us to explain molecular recoiling stress relaxation using a rather simplistic approach involving segmental level molecular rearrangements in polymer chains by attaining transient metastable states through an entropically activated process driving toward equilibrium. [ABSTRACT FROM AUTHOR]

The demand for applications, such as coatings, separation filters, and electronic packaging, has greatly driven the research of polymer films. At nanometer scale, mechanical properties of thin polymer films can significantly deviate from bulk. Despite outstanding progresses, there still lack deep discussions on nonlinear viscoelastic–viscoplastic response and their interactions under nanoconfinement. In this work, by conducting measurements via the bubble inflation method and modelling using Schapery and Perzyna equations, we demonstrate nonlinear viscoelastic–viscoplastic properties of freely standing thin polystyrene (PS) films. The results show the unchanged glassy compliance and the rubbery stiffening phenomenon for thin PS films, where the lower rubbery plateau in rubbery stiffening may originate from the induced molecular orientation by plastic deformation. With decreasing film thickness, viscosity and yield stress in viscoplasticity increase in an exponential and a linear trend, respectively, indicating the significant role of nanoconfinement effect on viscoplastic properties. These findings may reveal that there are many properties from linear viscoelasticity to nonlinear viscoelasticity–viscoplasticity that need to be explored and unveiled for sufficient understanding of the nanoconfinement effect on altering mechanical behavior of polymers. [ABSTRACT FROM AUTHOR]

Glass-forming liquids exhibit long-lived, spatially correlated dynamical heterogeneity, in which some nm-scale regions in the fluid relax more slowly than others. In the nanoscale vicinity of an interface, glass-formers also exhibit the emergence of massive interfacial gradients in glass transition temperature Tg and relaxation time τ. Both of these forms of heterogeneity have a major impact on material properties. Nevertheless, their interplay has remained poorly understood. Here, we employ molecular dynamics simulations of polymer thin films in the isoconfigurational ensemble in order to probe how bulk dynamic heterogeneity alters and is altered by the large gradient in dynamics at the surface of a glass-forming liquid. Results indicate that the τ spectrum at the surface is broader than in the bulk despite being shifted to shorter times, and yet it is less spatially correlated. This is distinct from the bulk, where the τ distribution becomes broader and more spatially organized as the mean τ increases. We also find that surface gradients in slow dynamics extend further into the film than those in fast dynamics—a result with implications for how distinct properties are perturbed near an interface. None of these features track locally with changes in the heterogeneity of caging scale, emphasizing the local disconnect between these quantities near interfaces. These results are at odds with conceptions of the surface as reflecting simply a higher "rheological temperature" than the bulk, instead pointing to a complex interplay between bulk dynamic heterogeneity and spatially organized dynamical gradients at interfaces in glass-forming liquids. [ABSTRACT FROM AUTHOR]

We report on the application of solution-based p-type electrical doping using 12-molybdophosphoric acid hydrate (PMA) to the fabrication of organic tandem solar cells. Such a doping approach leads to a spatially confined vertical doping profile down to a limited depth from the surface of polymer films, thus allowing the hole-collecting component of the charge recombination stack to be embedded in the photoactive layer of the bottom sub-cell. This simplifies the device architecture by removing the need for an extra dedicated hole-collecting layer. It is shown that this novel charge recombination stack comprising a PMA-doped bottom photoactive layer and a trilayer of Ag/AZO/PEIE is compatible with a solution-processed top photoactive layer. The fabricated inverted organic tandem solar cells exhibit an open-circuit voltage that is close to the sum of the open-circuit voltages of the individual sub-cells, and a fill factor that is close to the better fill factor of the two sub-cells. [ABSTRACT FROM AUTHOR]

An anion-responsive boron-containing π-conjugated polymer was synthesized via the Sonogashira coupling polymerization. The 11B NMR, UV/vis absorption, and fluorescence spectra confirmed the formation of an anion complex between the polymer and tetrabutylammonium fluoride (TBAF). Thin films were then prepared either by the pre-addition method, where the thin film was prepared using a solution of the polymer and TBAF, or by the post-addition method, where the polymer thin film was treated with an aqueous TBAF solution. The contact angle measurements revealed an enhancement in wettability with both methods. Consequently, wettability can be controlled via anion-complex formation at the surface. [ABSTRACT FROM AUTHOR]

Surface proton hopping conduction (SPHC) mechanisms is an important proton conduction mechanism in conventional polymer electrolytes, along with the Grotthuss and vehicle mechanisms. Due to the small diffusion coefficient of protons in the SPHC mechanism, few studies have focused on the SPHC mechanism. Recently, it has been found that a dense alignment of SO3− groups significantly lowers the activation energy in the SPHC mechanism, enabling fast proton conduction. In this study, a series of polymerizable amphiphilic‐zwitterions is prepared, forming bicontinuous cubic liquid‐crystalline assemblies with gyroid symmetry in the presence of suitable amounts of bis(trifluoromethanesulfonyl) imide (HTf2N) and water. In situ polymerization of these compounds yields gyroid‐nanostructured polymer films, as confirmed by synchrotron small‐angle X‐ray scattering experiments. The high proton conductivity of the films on the order of 10−2 S cm−1 at 40 °C and relative humidity of 90% is based solely on the SPHC mechanism. [ABSTRACT FROM AUTHOR]

Bio-artificial photosynthetic systems can reduce CO2 into multicarbon compounds by simulating natural photosynthesis. Here, inspired by organic photovoltaic structures, we demonstrate a bio-artificial photosynthetic system based on the hybridization of polymer semiconductor films and bacteria. The study suggests that the polymer-based semiconductor film can efficiently drive the non-photosynthetic bacteria to convert CO2 to acetate. By systematically characterizing the charge transport behavior of the bio-artificial photosynthetic system, the bulk-heterojunction structure and charge transport layers are proven to enhance the system performance markedly. The scalable floating artificial bio-leaf system can produce acetate to gram scale in a week. Notably, the semiconductor film is easy to recycle and maintains stable performance, showing good sustainable production capability of the system. A quasi-solid-state artificial bio-leaf is successfully prepared using agar to simulate the morphology and function of natural leaves. Last, the acetate production converted from CO2 was used to grow yeast for food production, thus achieving a complete simulation of natural photosynthesis. [ABSTRACT FROM AUTHOR]

Electrocaloric (EC) cooling presents a promising approach to efficient and compact solid-state heat pumps. However, reported EC coolers have complex architectures and limited cooling temperature lift. In this work, we introduce a self-regenerative heat pump (SRHP) using a cascade of EC polymer film stacks, which have electrostrictive actuations in response to an electric field that are directed to realize efficient heat transfer, eliminating the need for additional transportive or regenerative mechanisms. The SRHP demonstrates a cooling of 8.8 kelvin below ambient temperature in 30 seconds and delivers a maximum specific cooling power of 1.52 watts per gram. The temperature lift of the SRHP is 14.2 kelvin. These results underscore the potential of the compact solid-state cooling mechanism to address the increasing need for localized thermal management. [ABSTRACT FROM AUTHOR]

Neurons are essential cells composing our nervous system and orchestrating our body, thoughts, and emotions. Recently, research efforts have been focused on studying not only their collective structure and functions but also the single-cell properties as an individual complex system. Nanoscale technology has the potential to unravel mysteries in neuroscience and provide support to the neuron by measuring and influencing several aspects of the cell. As wearable devices interact with different parts of our body, we could envision a thousand times smaller interface to conform on and around subcellular regions of the neurons for unprecedented contact, probing, and control. However, a major challenge is to develop an interface that can morph to the extreme curvatures of subcellular structures. Here, we address this challenge with the development of a platform that conforms even to small neuronal processes. To achieve this, we produced a wireless platform made of an azobenzene polymer that undergoes on-demand light-induced folding with sub-micrometer radius of curvature. We show that these platforms can be fabricated with an adjustable form factor, micro-injected onto neuronal cultures, and can delicately wrap various morphologies of neuronal processes in vitro, toward obtaining seamless biointerfaces with an increased coupling with the cell membrane. Our in vitro testings did not show any adverse effects of the platforms in contact with the neurons. Additionally, for future functionality, nanoparticles or optoelectronic materials could be blended with the azobenzene polymer, and 2D materials on the platform surface could be safely folded to the high curvatures without mechanical failure, as per our calculations. Ultimately, this technology could lay the foundation for future integration of wirelessly actuated materials within or on its platform for neuromodulation, recording, and neuroprotection at the subcellular level. Neuronal behavior can be controlled by probing and modulating subcellular regions of the cells; however, developing an interface that can morph into the extreme curvatures of neurites is a major challenge. Here, the authors develop a wireless platform made of an azobenzene polymer that undergoes on-demand light-induced folding with an ultra-low curvature radius and wraps various morphologies of neuronal processes in vitro. [ABSTRACT FROM AUTHOR]

Ultralow temperature storage has sparked considerable attention with the development of the economy, showing promising applications ranging from biomedical to national defense and other fields. However, the development of ultralow temperature detection is constrained by the brittleness of current materials at low temperatures and the complexity of detection techniques. Consequently, the challenge exists in finding efficient solutions to material tolerance issues and achieving rapid detection of ultralow temperature. Herein, a novel flexible cross–linked polymer TPTA@PU film with long afterglow, high phosphorescence quantum efficiency, and excellent mechanical properties are successfully fabricated. Interestingly, the obtained TPTA@PU films demonstrate a notable thermoresponsive behavior, with the afterglow color shifting rapidly from blue to green within the temperature ranges from 80 to 280 K. Additionally, there is a positive linear correlation between the RGB values of the afterglow color and the corresponding temperature. Based on these prominent features, an ultralow temperature sensor is realized by utilizing TPTA@PU films as thermoresponsive elements. This work can be expected to provide more inspiration and possibilities for using RTP materials in a more cutting‐edge field. [ABSTRACT FROM AUTHOR]

Polyamide plays a pivotal role in engineering thermoplastics. Constrained by the harsh conditions and arduous procedures for its industrial synthesis, developing facile synthesis of polyamides is still challengeable and holds profound significance. Herein, we successfully utilized water as one of the monomers to synthesize functional polyamides under ambient conditions. A powerful multicomponent polymerization of water, isocyanides, and chlorooximes was established in phosphate‐buffered saline. Soluble and thermally stable polyamides with high weight‐average molecular weights (up to 53 900) were obtained in excellent yields (up to 95 %). The polymerization exhibits unique polymerization‐induced emission characteristics, successfully converting non‐emissive monomers into unconventional emissive polymers. Notably, the resultant polyamides could undergo effective post‐modification via the hydroxyl‐yne click reaction. By incorporating various functional groups into the polyamide, its emission color could be fine‐tuned from blue to green and to red. Remarkably, the refractive index (n) of the polyamide at 589 nm could be increased from 1.6173 to 1.7227 and the Δn could be unprecedentedly as high as 0.1054 for non‐heavy atom‐containing polymers after post‐modification, and its micron‐thick films exhibited excellent transparency in the visible region. Thus, this work not only establishes a powerful polymerization toward novel polyamides but also opens up an avenue for their versatile functionalization. [ABSTRACT FROM AUTHOR]

Polyamide plays a pivotal role in engineering thermoplastics. Constrained by the harsh conditions and arduous procedures for its industrial synthesis, developing facile synthesis of polyamides is still challengeable and holds profound significance. Herein, we successfully utilized water as one of the monomers to synthesize functional polyamides under ambient conditions. A powerful multicomponent polymerization of water, isocyanides, and chlorooximes was established in phosphate‐buffered saline. Soluble and thermally stable polyamides with high weight‐average molecular weights (up to 53 900) were obtained in excellent yields (up to 95 %). The polymerization exhibits unique polymerization‐induced emission characteristics, successfully converting non‐emissive monomers into unconventional emissive polymers. Notably, the resultant polyamides could undergo effective post‐modification via the hydroxyl‐yne click reaction. By incorporating various functional groups into the polyamide, its emission color could be fine‐tuned from blue to green and to red. Remarkably, the refractive index (n) of the polyamide at 589 nm could be increased from 1.6173 to 1.7227 and the Δn could be unprecedentedly as high as 0.1054 for non‐heavy atom‐containing polymers after post‐modification, and its micron‐thick films exhibited excellent transparency in the visible region. Thus, this work not only establishes a powerful polymerization toward novel polyamides but also opens up an avenue for their versatile functionalization. [ABSTRACT FROM AUTHOR]

Achieving amorphous polymers with ultralong room‐temperature phosphorescence (RTP), tunable organic afterglow, and reversible photoactivation behavior is highly desirable for practical applications but challenging. Herein, simple positional isomers with three carboxyl groups located in the ortho, meta, and para positions of the triphenylamine skeleton are designed and synthesized. By physically blending with the poly(vinyl alcohol) matrix, these isomers show ultralong RTP properties, among which the meta‐isomer has the longest RTP lifetime (620.1 ms). Theoretical calculations reveal that the more efficient intersystem crossing, the slower radiative decay rate of the lowest triplet excitons, and stronger intermolecular hydrogen‐bonding interactions should be responsible for the superior RTP property of meta‐isomer. Furthermore, the tunable organic afterglow is readily realized via a triplet‐to‐singlet energy transfer process. More impressively, the meta and para isomers exhibit reversible photoactivated ultralong RTP properties after embedding into the rigid poly(methyl methacrylate) matrix. Finally, amorphous and flexible polymer films prepared from these positional isomers show potential applications in advanced anti‐counterfeiting and multilevel encryption through subtly combining ultralong RTP lifetime, tunable organic afterglow, and reversible photoactivation behavior. [ABSTRACT FROM AUTHOR]

Cobaltocenium-containing (co)polysiloxanes (Cc-PDMSs) with terminal and side groups were synthesized by the reaction of catalyst-free hydroamination between ethynylcobaltocenium hexafluorophosphate and polysiloxanes comprising amino moieties as terminal and side groups. The conversion of NH2 groups in the polymers reaches 85%. The obtained (co)polysiloxanes "gelate" due to an increase in their molecular weight by approx. 30 times, when stored at room temperature over one week. "Gelated" Cc-PDMSs remain soluble in most polar solvents. The structure of Cc-PDMSs and the mechanism of "gelation" were established by 1H, 13C{1H}, 29Si{1H}, 19F{1H}, 31P{1H} nuclear magnetic resonance, infrared, ultraviolet–visible, and X-ray photoelectron spectroscopies. As determined by cyclic voltammetry, Cc-PDMSs possess redox properties (CoII/CoIII transitions at E1/2 = −1.8 and −1.3 V before and after "gelation", respectively). This synthetic approach allows to increase the molecular weights of the synthesized polysiloxanes functionalized with cobaltocenium groups easily, leading to their higher film-forming ability, which is desirable for some electronic applications. Cc-PDMSs can be utilized as redox-active polymer films in modified electrodes, electrochromic devices, redox-active coatings, and components for batteries. [ABSTRACT FROM AUTHOR]

Hydrogen sensors are important in a hydrogen‐driven society to prevent explosions caused by hydrogen leaks into the atmosphere. In previous studies, resistive hydrogen sensors on polymer films have metal oxide nanostructures decorated with novel metals that enable good responses at room temperature. However, the in situ growth process of sensing nanostructures has the disadvantage of ineffective fabrication, particularly when preparing a thick catalyst layer to produce reliable readouts from the catalytic hydrogen combustion. This work presents a catalytic combustion hydrogen sensor with a thick catalyst layer anchored in a UV resin layer on polyimide film. Catalyst anchoring channels are made by UV imprinting with a glass mold. The sensor consists of a sensing electrode and a microheater, both made of Au within an area of 1.2 mm diameter. UV imprinting produces a UV resin layer of 27 µm thick and catalyst anchoring channels of 14 µm deep and 20–30 µm wide, which are filled with Pt/TiO2 as a catalyst. The sensing response is 7.9% for 1% H2 under ambient conditions, and the detection range is 0.1–3% H2. The UV‐resin microstructures can effectively retain a thick catalyst layer to enhance sensitivity, and their low thermal conductivity reduces heat loss. [ABSTRACT FROM AUTHOR]

Designing the donor–acceptor polymers‐based modifiers with good charge mobility and abundant surface functional groups to bind on perovskite material is highly demanded to boost interfacial charge extraction and transport while yet realized. Here, two [WS4Cu4Br]+ and [WS4Cu5Br2]+ cluster units are bridged by triphenylamine ligands to yield an unprecedented a heteronuclear W/Cu/S clusters‐based donor–acceptor polymer. Due to the effect of Rydberg orbital components in different clusters mainly contributed by Cu ions, Cu‐rich units have negative potential, whereas Cu‐deficient groups display positive potential. This facilitates the formation of a circuit network with ligands acting as "wires" to realize efficient charge transport. Mobility tests reveal that the hole mobility of polymer film is 3.81 × 10−5 cm2 V−1 s−1. Such a polymer can efficiently extract and transport the holes from perovskite film, and thus improving the cell performance and stability. This work opens the opportunities for designing donor–acceptor polymers based on heteronuclear W/Cu/S clusters. [ABSTRACT FROM AUTHOR]

The role of pressure, temperature, and particle size on cold sintering of ZnO has been investigated with a view to developing transparent thick films for device applications. Coarse ZnO (∼90–250 nm, cZnO) particles exhibited equiaxed grain growth under all conditions eventually achieving grain sizes of ∼ 0.5–1.0 µm at 300°C/375 MPa. In contrast, nano‐ZnO (40–80 nm, nZnO), exhibited grain growth along the c‐axis with a broader grain size distribution (0.5–4 µm) at higher temperatures and pressure (300°C/375 MPa) than cZnO. The broader grain size distribution is attributed to greater dissolution for nZnO compared with cZnO coupled with redistribution of Zn acetate/acetic acid into pores. ZnO continues to dissolve and reprecipitate within the pores throughout the densification process resulting in localized, larger grain sizes. In plane grain growth normal to the pressing direction was observed at and near the sample surface particularly in nZnO, which is attributed to constrained‐sintering. Some abnormal grain growth (10–20 µm) was also sporadically observed near or at the surface of nZnO (300°C/375 MPa) due to greater rates of reprecipitation as the transient solvent volatilizes adjacent to the die wall/plunger. Tape casting was used to fabricate single and multiple layers (≈30 µm) of ZnO on Kapton® to demonstrate the potential for device fabrication. Transparency was achieved by choosing cold sintering conditions (200°C/250 MPa) for nZnO that gave ∼95% relative density while restricting a majority of grain growth to <200 nm so that internal light scattering from grain boundaries was avoided. [ABSTRACT FROM AUTHOR]

Twelve liquid crystalline polymer network films were fabricated through photopolymerization of cholesteric liquid-crystalline mixtures containing two aggregation-induced emissive-active luminogens. The films exhibit multicolour and white circularly polarized luminescence with dissymmetry factors up to 0.85 and fluorescence quantum yields up to 90%. [ABSTRACT FROM AUTHOR]

Using angle-resolved X-ray photoelectron spectroscopy, sum-frequency generation vibrational spectroscopy, contact angle measurements, and molecular dynamics simulations, we verify that the glass transition temperature (Tg) of polymer glass is lower near the free surface. However, the experimental Tg-gradients showed a linear variation with depth (z) from the free surface, while the simulated equilibrium Tg-gradients exhibited a double exponential z-dependence. In typical simulations, Tg is determined based on the relaxation time of the system reaching a prescribed threshold value at equilibrium. Conversely, the experiments determined Tg by observing the unfreezing of molecular mobility during heating from a kinetically arrested, nonequilibrium glassy state. To investigate the impact of nonequilibrium effects on the Tg-gradient, we reduced the thermal annealing time in simulations, allowing the system to fall out of equilibrium. We observe a decrease in the relaxation time and the emergence of a modified z-dependence consistent with a linear Tg-gradient near the free surface. We further validate the impact of nonequilibrium effects by studying the dependence of the Tg on the heating/cooling rate for polymer films of varying thickness (h). Our experimental results reveal significant variations in the Tg-heating/cooling rate dependence with h below the bulk Tg, which are also observed in simulation when the simulated system is not equilibrated. We explain our findings by the reduction in mass density within the inner region of the system under nonequilibrium conditions, as observed in simulation, and recent research indicating a decrease in the local Tg of a polymer when placed next to a softer material. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV), visible, and near‐infrared (NIR) broadband organic photodetectors are fabricated by sequential solution‐based thin film coatings of a polymer electron blocking layer (EBL) and a polymer photoactive layer. To avoid damage to a preceding polymer EBL during a subsequent solution‐based film coating of a polymer photoactive layer due to lack of solvent orthogonality, 2‐(((4‐azido‐2,3,5,6‐tetrafluorobenzoyl)oxy)methyl)−2‐ethylpropane‐1,3‐diyl bis(4‐azido‐2,3,5,6‐tetrafluorobenzoate) (FPA‐3F) is used as a novel organic cross‐linking agent activated by UV irradiation with a wavelength of 254 nm. Solution‐processed poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)‐benzidine] (poly‐TPD) films, which are cross‐linked with a FPA‐3F photocrosslinker, are used for a preceding polymer EBL. A ternary blend film composed of PTB7‐Th, COi8DFIC, and PC71BM is used as a NIR‐sensitive organic photoactive layer with strong photosensitivity in multispectral (UV–visible–NIR) wavelengths of 300–1,050 nm. Poly‐TPD films are successfully cross‐linked even with a very small amount of 1 wt% FPA‐3F. Small amounts of FPA‐3F have little detrimental effect on the electrical and optoelectronic properties of the cross‐linked poly‐TPD EBL. Finally, organic NIR photodetectors with a poly‐TPD EBL cross‐linked by the small addition of FPA‐3F (1 wt%) show the detectivity values higher than 1 × 1012 Jones for the entire UV–visible–NIR wavelengths from 300 nm to 1050 nm, and the maximum detectivity values of 1.41 × 1013 Jones and 8.90 × 1012 Jones at the NIR wavelengths of 900 and 1000 nm, respectively. [ABSTRACT FROM AUTHOR]

Barium titanate (BTO) is well-known (as a photo- or sono/piezo-catalyst) to produce hydrogen peroxide via 2-electron reduction of oxygen in the presence of a sacrificial quencher, such as isopropanol. While barium titanate nanoparticles with a tetragonal crystal structure (piezoelectric) are particularly reactive, the recovery and reuse of these nano-catalysts from reactions can be difficult. Here, barium titanate nanoparticles of typically 200 nm to 600 nm diameter are embedded into a host film of a polymer of intrinsic microporosity (PIM-EA-TB). Due to molecular rigidity of the polymer, there is no capping effect, and the surface catalytic reaction occurs effectively with a catalyst embedded in the polymer. In this exploratory work, the catalytic formation of H2O2 in the presence of isopropanol is investigated via kinetic studies and by electron paramagnetic resonance (EPR). Perhaps surprisingly, at a neutral pH the rate of the catalytic reaction is substantially increased when barium titanate is embedded into the polymer host and when the polymer is protonated. This is attributed here to a "kinetic cage effect" which exploits the tertiary amine in the polymer backbone with anodic and cathodic processes coupled into a pH neutral reaction. [ABSTRACT FROM AUTHOR]

Background/Objectives: Coated drug pellets enjoy widespread use in hard gelatine capsules. In heterogeneous pellets, the drug substance is layered onto core pellets. Coatings are often applied to generate a retarded release or an enteric coating. Methods: In the present study, the thickness of a polymer coating layer on drug pellets was correlated to the drug release kinetics. Results: The question should be answered whether it is possible to stop the coating process when a layer thickness referring to an intended drug release is achieved. Inert pellets were first coated with sodium benzoate and second with different amounts of water insoluble polyacrylate in a fluidized bed apparatus equipped with a Wurster inlet. The whole process was controlled in-line and at-line with process analytical technology by the measurement of the particle size and the layer thickness. The in-vitro sodium benzoate release was investigated, and the data were linearized by different standard models and compared with the polyacrylate layer thickness. With increasing polyacrylate layer thickness the release rate diminishes. The superposition of several processes influencing the release results in release profiles corresponding approximately to first order kinetics. The coating layer thickness corresponds to a determined drug release profile. Conclusions: The manufacturing of coated drug pellets with intended drug release is possible by coating process control and layer thickness measurement. Preliminary investigations are necessary for different formulations. [ABSTRACT FROM AUTHOR]

A systematic investigation of optical, electrochemical, photophysical, and electrooptical properties of printable green color-emitting polymer (poly(9,9-dioctylfluorene-alt-bithiophene)) (F8T2) and spiro-copolymer (SPG-01T) was conducted to explore their potentiality as an emissive layer for wearable polymer light-emitting diode (PLED) applications. We compared the two photoactive polymers in terms of their spectral characteristics and color purity, as these are the most critical factors for wearable lighting sources and optical sensors. Low-cost, solution-based methods and facile architecture were applied to produce rigid and flexible light-emitting devices with high luminance efficiencies. Emission bandwidths, color coordinates, operational characteristics, and luminance were also derived to evaluate the device's stability. The tuning of emission's spectral features by layer thickness variation was realized and was correlated with the interplay between H-aggregates and J-aggregates formations for both conjugated polymers. Finally, we applied the functional green light-emitting PLED devices based on the two studied materials for the detection of Rhodamine 6G. It was determined that the optical detection of the R6G photoluminescence is heavily influenced by the emission spectrum characteristics of the PLED and changes in the thickness of the active layer. [ABSTRACT FROM AUTHOR]

Polymer‐based pyroelectric thin films are crucial functional materials at the core of flexible and lightweight electronic devices, such as wearable monitoring sensors, energy harvesters, and infrared detectors. Nevertheless, the pyroelectric properties of the polymer films, such as poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)), vanish when the surrounding temperature exceeds the ferroelectric‐to‐paraelectric transition temperature, and thus limits their pyroelectric performance to a low‐temperature range. Herein, to mitigate this issue by employing a new class of P(VDF‐TrFE) copolymer which has a low TrFE molar content is proposed. Fine‐tuning of the structure through thermal annealing in a vacuum environment significantly favors robust and highly polarized polymer films with a large area. Electric poling combined with an optimal annealing temperature (110–120 °C) gives highly ordered ferroelectric crystalline domains in the polymer films. Consequently, this remarkably broadens the temperature range (roughly up to 140 °C) for which the polymer film still presents high pyroelectric properties (pyroelectric coefficient 50 µC (m2K)−1). This study provides an alternative choice for pyroelectric polymer films with enhanced pyroelectricity in applications that require wider temperature ranges. [ABSTRACT FROM AUTHOR]

Two‐dimensional polymers (2DPs) and their layer‐stacked 2D covalent organic frameworks have recently emerged as nonlinear optical (NLO) materials for potential applications in optics. However, the chemistry for designing third‐order NLO 2DP films with large nonlinear absorption coefficient (β) has remained a mystery. Herein, three highly crystalline porphyrin‐integrated 2D polyimines (named as 2DPI‐Zn‐Azo, 2DPI‐2H‐Azo, and 2DPI‐Zn), which are homogeneous films showing large lateral areas over cm2, uniform transparency, and thickness of tens of nanometers are reported. Particularly, the 2DPI‐Zn‐Azo film comprising zinc porphyrin and –NN– displays a large saturable absorption under 532 nm and the highest β (−1.88 × 105 cm GW−1) among the three 2D polyimines, that is also 2–5 orders of magnitude higher than the state‐of‐art performance of photoactive small molecules, porphyrin‐integrated 2DPs, and inorganic 2D materials. Control experiments in combination with theoretical calculation discover that the embedding of metal centers and –NN– results in highly delocalized π‐electrons and narrow bandgap in 2DPI‐Zn‐Azo, which enables fast transfer of the photogenerated electrons after the light‐excited charge separation, thus boosting the NLO performance. This work opens up a new path for the construction of highly efficient third‐order NLO film materials, and pushes the development of 2DPs for optics and optoelectronics. [ABSTRACT FROM AUTHOR]

Medicinal plant of Senna alata (S. alata) extract incorporated into Polyvinyl alcohol (PVA) film was successfully synthesized through a solution casting technique. The surface morphology of PVA/S. alata film was characterized by FE-SEM, which revealed the smooth and homogenous surface of the film and indicated the dispersion of S. alata in the PVA matrix. PVA functional group of hydroxyl and principal component of S. alata leaves flavonoids and anthraquinones presented in PVA/S. alata film was confirmed by FTIR spectra. XRD pattern results showed the crystallinity nature of PVA/S. alata film. Thermal analysis (TGA/DTG) demonstrated that incorporating S. alata extract in the PVA matrix enhanced the film thermal stability. In-vitro scratch wound assay was studied for PVA/S. alata film. The maximum wound healing activity of 93% was attained at 24 h with interaction on the mouse fibroblast L929 cell line, and wound gap width was measured through Image J software. Therefore, the developed PVA/S. alata film shows significant potential as an effective wound dressing material. [ABSTRACT FROM AUTHOR]

Multilayer polymer films are extensively used in multiphase separation. Electrospray deposition (ESD) is an important technique for fabricating such films with tunable morphology. Viscoelastic properties of polystyrene (PS) nanoshell coatings produced by ESD on gold and spin‐coated PS surfaces are evaluated using Quartz Crystal Microbalance with Dissipation (QCM‐D). The thickness of PS films on gold increases with flow rate from ∼200 nm at 0.5 to ∼400 nm at 1.5 mL h−1, accompanied by an order‐of‐magnitude increase in dissipation due to larger particle sizes from shorter droplet flight times. This effect is absent on spin–coated PS films, suggesting the onset of the self‐limiting effect of charges. Although the shear moduli for ESD films calculated from Voigt models is only 0.08%–0.20% of the bulk PS modulus, the stiffness ratio of spray‐coated PS to a single shell is (5.00–13.3) × 103 m−1, due to shell–shell and shell–substrate interactions. These are novel results related to the interparticle friction obtained using QCM‐D for the first time. This work demonstrates  that mechanical properties of particulate viscoelastic films with potential applications in high surface area sensors, such as size‐selective membranes for protein or electrolyte adsorption, can be evalauted by QCM‐D with nanograms of material. [ABSTRACT FROM AUTHOR]

A stimuli‐responsive multiple chirality switching material, which can regulate opposed chiral absorption characteristics, has great application value in the fields of optical modulation, information storage and encryption, etc. However, due to the rareness of effective functional systems and the complexity of material structures, developing this type of material remains an insurmountable challenge. Herein, a smart polymer film with multiple chirality inversion properties was fabricated efficiently based on a newly‐designed acid & base‐sensitive dye‐grafted helical polymer. Benefited from the cooperative effects of various weak interactions (hydrogen bonds, electrostatic interaction, etc.) under the aggregated state, this polymer film exhibited a promising acid & base‐driven multiple chirality inversion property containing record switchable chiral states (up to five while the solution showed three‐state switching) and good reversibility. The creative exploration of such a multiple chirality switching material can not only promote the application progress of current chiroptical regulation technology, but also provide a significant guidance for the design and synthesis of future smart chiroptical switching materials and devices. [ABSTRACT FROM AUTHOR]

A stimuli‐responsive multiple chirality switching material, which can regulate opposed chiral absorption characteristics, has great application value in the fields of optical modulation, information storage and encryption, etc. However, due to the rareness of effective functional systems and the complexity of material structures, developing this type of material remains an insurmountable challenge. Herein, a smart polymer film with multiple chirality inversion properties was fabricated efficiently based on a newly‐designed acid & base‐sensitive dye‐grafted helical polymer. Benefited from the cooperative effects of various weak interactions (hydrogen bonds, electrostatic interaction, etc.) under the aggregated state, this polymer film exhibited a promising acid & base‐driven multiple chirality inversion property containing record switchable chiral states (up to five while the solution showed three‐state switching) and good reversibility. The creative exploration of such a multiple chirality switching material can not only promote the application progress of current chiroptical regulation technology, but also provide a significant guidance for the design and synthesis of future smart chiroptical switching materials and devices. [ABSTRACT FROM AUTHOR]

Multifunctional thin films are becoming extremely popular in many technological fields. An increase in their functionality can be achieved by the creation of nanocomposite structures. This study represents novel thin composite coatings with a horizontally oriented single-walled carbon nanotube (SWCNT) filler inside a silicon oxynitride (SiO x N y) matrix obtained by (i) low-temperature thermal curing or by (ii) UV radiation-induced curing. The SiO x N y /SWCNT composite structures were prepared by simple dry transfer of a SWCNT film into a perhydropolysilazane (PHPS) polymer matrix film deposited by the spin-coating technique followed by curing. The structural, morphological, and optical properties of the SiO x N y /SWCNT composite films were studied using HR-SEM/EDX, ATR-FTIR, and UV–Vis spectroscopy. It was found that SWCNT films were uniformly transferred into the PHPS matrix, maintaining their horizontally oriented close-packed structure, and avoiding the problem of agglomeration, thereby forming a laminate-type composite. SWCNTs had no effect on the curing process of the PHPS matrix. The SWCNT concentration remained relatively low, resulting in highly transparent composite films. An antireflection effect in the composite film relative to the transmission of the SWCNT film was observed. The results indicate that SiO x N y /SWCNT composites are attractive for applications as protective, antireflective optical coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

Novel tetrafluoro-λ6-sulfanyl-containing oligomers prepared by visible light-promoted addition of 1,4-(bis-chlorotetrafluoro-λ6-sulfanyl) benzene or 1,3-(bis-chlorotetrafluoro-λ6-sulfanyl) benzene to either 1,4-diethynyl benzene or the 1,3-diethynyl isomers form hard, stress resistant thin films on spin casting. The isomeric oligomers were utilized to establish a structure-function relationship for the mechanical properties of films prepared from the oligomers. The Young's moduli of 145-nm-thick cured films could reach 60 GPa. The measured hardnesses, between 1.57 and 2.77 GPa, were more than double those of polymethyl methacrylate (PMMA) films. Curing of the tetrafluoro-λ6-sulfanyl-containing polymer films by UV irradiation resulted in coatings that exhibited remarkable hardness and modulus with good surface adhesion to silicon. [ABSTRACT FROM AUTHOR]

Metathesis homo- and copolymerization of bifunctional monomers bearing two norbornene moieties was studied. The monomers were synthesized from cis-5-norbornene-exo-2,3-dicarboxylic anhydride and various diamines (hexamethylenediamine, decamethylenediamine, 1R,3S-isophoronediamine). The metathesis homopolymerization of these bis(nadimides) in the presence of the second-generation Grubbs catalyst afforded glassy cross-linked polymers in more than 90% yields. The metathesis copolymerization of the bis(nadimides) and a monofunctional norbornene derivative containing the β-pinene fragment also resulted in insoluble cross-linked polymers in nearly quantitative yields. The structures and purity of the synthesized polymers were confirmed via IR spectroscopy and CP/MAS NMR spectroscopy. Conditions for the fabrication of mechanically strong solution-cast thin films based on copolymers synthesized from the comonomers mentioned above were determined by varying the content of the cross-linking agent. It was shown that the films made in this way are stable in a range of organic solvents and could be useful as semipermeable or membrane materials for use in liquid organic media. The permeability of the polymer films in question to 1-phenylethanol and mandelic acid was studied. The results obtained are discussed along with the data from the DSC, TGA, and powder X-ray diffraction studies of the properties of the synthesized metathesis homo- and copolymers. [ABSTRACT FROM AUTHOR]

Silica (SiO2) particles are widely used in various industries due to their chemical inertness, thermal stability, and wear resistance. The present study describes the preparation and potential use of porous hydrophobic and hydrophilic SiO2 microcapsules (MCs) of a narrow size distribution. First, various layers of SiO2 micro/nano-particles (M/NPs) were grafted onto monodispersed polystyrene (PS) microspheres of a narrow size distribution. Hydrophobic and hydrophilic sintered SiO2 MCs were then prepared by removing the core PS from the PS/SiO2 core–shell microspheres by burning off under normal atmospheric conditions or organic solvent dissolution, respectively. We examined how the size and quantity of the SiO2 M/NPs influence the MC's properties. Additionally, we utilized two forms of hollow SiO2 MC for different applications; one form was incorporated into polymer films, and the other was free-floating. The hydrophobic microcapsules filled with 6% hydrogen peroxide were effective in killing the tomato brown rugose fruit virus (ToBRFV). The hydrophilic microcapsules filled with thymol and thin coated onto polypropylene films were successfully used to prevent mold formation for hay protection. [ABSTRACT FROM AUTHOR]

ABSTRACT This work aims to investigate the influence of the substrate temperature on low‐pressure plasma polymerization processes. Emphasis is placed on the mechanical properties and growth mechanism of the plasma polymer films (PPFs). For this purpose, two precursors are considered, differing only by their unsaturation degree: 2‐propen‐1‐ol (CH2═CH–CH2–OH) and propan‐1‐ol (CH3–CH2–CH2–OH). Although propan‐1‐ol‐based PPFs behave like hard elastic solids, 2‐propen‐1‐ol‐based coatings evolve from a liquid film to an elastic solid on increasing the substrate temperature. This behavior is understood considering the evolution of the glass transition temperature of PPFs. The latter is correlated with the cross‐linking degree of the polymeric network governed by the energy density of bombarding ions on the growing film. [ABSTRACT FROM AUTHOR]

Smart materials with circularly polarized luminescence (CPL) tunable ability show great potential for advanced information storage and encryption. While an effective integration of high photoluminescence quantum yield (PLQY) and facile regulation of CPL property in thin films are of great significance, it is challenging due to the scarcity of suitable materials and complexity of systems. Herein, a novel acid‐responsive CPL tunable molecule is designed by combining an aggregation‐induced emission (AIE) component (TPE), an acid‐responsive luminophore (Rhodol), and a chiral aniline. Benefitting by the “AIE” effect of TPE and acid‐sensitive nature of Rhodol, the acidified molecule (S‐Rhodol‐TPE) exhibits a high PLQY even when doped in the polymer substrate at high concentrations. In addition, due to the fluorescence resonance energy transfer (FRET) process between TPE and Rhodol, the emission color of S‐Rhodol‐TPE can be easily regulated by the doped ratio and acidified degree of S‐Rhodol‐TPE in the polymer film. This work exhibits a unique approach to achieving smart CPL‐tunable films with high PLQYs and multiple emission color‐regulation properties, which can undoubtedly facilitate the progress of CPL tunable materials. [ABSTRACT FROM AUTHOR]

A poly(para)phenylene conjugated polymer is developed to store information via a quick and facile optical writing method. After exposure to UV light, co‐fluorescence (films with two or more written emission colors –, i.e., "double‐on") and "on‐off" states are written into the flexible polymer films. The hidden information is invisible under ambient lighting and can only be read with an appropriate light source, optical filter, and/or magnifier, thus providing a level of security for information encoded into the films. The physical and chemical mechanisms are discussed responsible for the rapid fluorescence changes that occur under UV exposure and demonstrate microscale multi‐colored artwork and hidden QR codes written into pliable and freestanding films. Depending on the preparation, the written patterns remained easily visible and stable after exposure to water and to ambient levels of UV background radiation. [ABSTRACT FROM AUTHOR]

This study focused on preparation of stable polymer films of NiII‐ and CoII‐tetraaminophthalocyanines, p‐NiTAPc and p‐CoTAPc, respectively, for highly efficient heterogeneous electrochemical carbon dioxide (CO2) reduction in a flow electrolysis cell. Major development represented in this work was fabrication of p‐NiTAPc and p‐CoTAPc films via electropolymerization of their corresponding monomers on carbon‐based substrates without using binder or conducting additive materials to obtain efficient gas diffusion electrodes (GDEs) for scalable, productive and selective CO2‐to‐CO conversion. The target polymers were characterized by UV‐visible spectrophotometry, attenuated total reflection‐Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy and cyclic voltammetry. According to controlled potential electrolysis and gas chromatography, p‐NiTAPc‐catalyzed CO2 reduction at −0.99 V vs. reversible hydrogen electrode (RHE) gave 953 mL of CO in a period of 16 hours with current density and Faradaic efficiency (FE) of 109±1 mA ⋅ cm−2 and 99±2 %, respectively. A p‐CoTAPc‐modified GDE exhibited superior catalytic performance to the case of p‐NiTAPc in terms of catalyst stability and CO productivity by performing the continuous CO2 reduction at the potential of −1.10 V vs. RHE for up to 41 hours and affording almost 3 times higher amount of CO with the current density of 161±5 mA⋅cm–2 and 95±2 % FE. [ABSTRACT FROM AUTHOR]

The optical and mechanical properties of 2D semiconductors make them excellent candidates for the active components of plastic optoelectronic devices. Here, the integration of single‐layer WSe2 (1L‐WSe2) into a polystyrene (PS) film containing dispersed perylene orange (PDI‐O) molecules is investigated. The findings reveal a notable enhancement in the light emission of 1L‐WSe2, which occurs exclusively upon PDI‐O excitation and scales with the concentration of molecules in the PS film. Moreover, the increase in 1L‐WSe2 photoluminescence coincides with a quenching of the PDI‐O light emission intensity and a decrease in its lifetime. These results point to efficient long‐range interactions, such as Förster energy transfer, between PDI‐O (acting as the donor) and 1L‐WSe2 (acting as the acceptor), as the mechanism responsible for the enhanced light emission in the latter. These findings are of great interest for the development of flexible optoelectronic devices integrating active 2D materials; the polymeric matrix plays a dual role, serving as both physical support and host for organic dopants that can optimize the light emission properties of the active 2D material. [ABSTRACT FROM AUTHOR]

Electrochromic polymers (ECPs) have great application potential in flexible displays, and there is an increasing expectation of using green methods to form ECP films. Herein, we propose a modified microemulsion method to prepare cyan/magenta/yellow (C/M/Y) water-dispersed electrochromic polymer nanoparticles (WDEN) systems. Three polymer films (WDECP-C/M/Y) maintain similar electrochemical properties compared to their corresponding organic solvent-based polymer films. It is intriguing that WDECP-C/M/Y exhibit better electrochromic properties in terms of higher cycling stability (97.24%, 95.05%, and 52.84%, respectively) and faster switching time (0.94 s, 1.09 s, and 1.34 s for coloring time, respectively) due to the introduction of nanoparticles. In addition, it can achieve various desired colors by blending the C/M/Y WDEN systems in different ratios. The calculated chromaticity coordinates of the blending polymer films show close values to the experimental observation, and the calculated Δ E * ab values range from 2.6 to 10.3, which may provide theoretical guidance for precisely color control. Finally, large-scale and patterned devices were assembled, which can achieve colored-to-colorless reversible electrochromism at a low driving voltage of 0–1.5 V. This work puts forward a universal and environmentally sustainable strategy to prepare WDEN systems, demonstrating their wide range of applications in display devices and electronic tags. [ABSTRACT FROM AUTHOR]

Many stimuli‐responsive materials harness the reversible association of supramolecular binding motifs to enable advanced functionalities such as self‐healing, switchable adhesion, or mechanical adaptation. Despite extensive research into the structure–property relationships of these materials, direct correlations between molecular‐level changes in supramolecular binding and macroscopic material behaviors have mostly remained elusive. Here, we show that this challenge can be overcome with supramolecular binding motifs featuring integrated binding indicators. We demonstrate this using a novel motif that combines a hydrogen‐bonding ureido‐4‐pyrimidinone (UPy) with two strategically placed pyrene fluorophores. Dimerization of this motif promotes pyrene excimer formation, facilitating the straightforward optical quantification of supramolecular assembly under various conditions. We exploit the new motif as a supramolecular cross‐linker in poly(methyl acrylate)s to probe the extent of (dis)assembly as a function of cross‐linker content, processing history, and applied stimuli. We demonstrate that the stimuli‐induced dissociation of hydrogen‐bonding linkages strongly depends on the initial cross‐link density, which also dictates whether the force‐induced dissociation in polymer films correlates with the applied stress or strain. Thus, beyond introducing a robust tool for the in situ study of dynamic (dis)assembly mechanisms in supramolecular systems, our findings provide new insights into the mechanoresponsive behavior of such materials. [ABSTRACT FROM AUTHOR]

Many stimuli‐responsive materials harness the reversible association of supramolecular binding motifs to enable advanced functionalities such as self‐healing, switchable adhesion, or mechanical adaptation. Despite extensive research into the structure–property relationships of these materials, direct correlations between molecular‐level changes in supramolecular binding and macroscopic material behaviors have mostly remained elusive. Here, we show that this challenge can be overcome with supramolecular binding motifs featuring integrated binding indicators. We demonstrate this using a novel motif that combines a hydrogen‐bonding ureido‐4‐pyrimidinone (UPy) with two strategically placed pyrene fluorophores. Dimerization of this motif promotes pyrene excimer formation, facilitating the straightforward optical quantification of supramolecular assembly under various conditions. We exploit the new motif as a supramolecular cross‐linker in poly(methyl acrylate)s to probe the extent of (dis)assembly as a function of cross‐linker content, processing history, and applied stimuli. We demonstrate that the stimuli‐induced dissociation of hydrogen‐bonding linkages strongly depends on the initial cross‐link density, which also dictates whether the force‐induced dissociation in polymer films correlates with the applied stress or strain. Thus, beyond introducing a robust tool for the in situ study of dynamic (dis)assembly mechanisms in supramolecular systems, our findings provide new insights into the mechanoresponsive behavior of such materials. [ABSTRACT FROM AUTHOR]

Redox processes in the polymer film of poly-N,N′-ethylenebis(3-methoxysalicylideneimine were studied for the first time by in situ methods including electron spin resonance spectroscopy, ultraviolet—visible—near-infrared spectroscopy, and Fourier transform infrared spectroscopy. The integration of the obtained data with the results of electrochemical nanomechanical atomic force microscopy measurements allowed us to determine causes of a low electrochemical oxidative polymerization efficiency of this compound and a rapid loss of its electrochemical activity in the oxidation—reduction processes. [ABSTRACT FROM AUTHOR]

[Display omitted] The effect of UV irradiation on sol–gel prepared ZnO films subjected to mild thermal annealing was investigated, with special attention to their structural and surface properties. Sol–gel processes, including a high-temperature annealing stage, have been adapted to the requirements of flexible electronics for in situ synthesis of semiconductor ZnO films on polymer substrates at lower temperatures due to UV irradiation. Application of UV radiation with emission peaks at 185 and 254 nm to films annealed at 180 °C made it possible to obtain ZnO films with Zn/O ratios of ca. 1, which cannot be achieved by heat treatment alone. [ABSTRACT FROM AUTHOR]

The roll‐to‐roll (R2R) process for fabricating elastic substrates is essential for the social implementation of next‐generation stretchable devices with soft interfaces. In recent years, there is a growing demand for soft heterostructures with multiple monolithically patterned organic materials. However, a continuous processing technique for substrates with heterostructures patterned using highly stretchable wiring has not yet been developed. Conventional manufacturing methods for stretchable electronics lack production capacity. This study introduces an R2R‐based method for the continuous production of multilayered substrates composed of various elastic materials, integrated with liquid metal (LM) wiring, suitable for stretchable electronics. Continuous fabrication of polymer films is achieved with pattern areas as small as 0.78 mm2, using three different polymers varying in hardness. The R2R coating process, paired with liquid metal wiring dispensing printing, allows for the creation of lines as fine as 140 microns. This process supports the batch production of 15 stretchable hybrid devices at a time and enables the creation of large‐area devices up to 400 cm2. The fabrication technique developed herein holds promise for the future manufacturing of not only stretchable electronics but also cutting‐edge soft electronics like smart packaging. This is expected to be a factor leading to the commercialization of stretchable electronics. [ABSTRACT FROM AUTHOR]