Polymer Films Research Articles

Ammonia and temperature sensing applications using fluorometric and colorimetric microparticles and polymeric films doped with BODIPY-emitters.

Fourfunctionalized BODIPY derivatives(BDP1 to BDP4) were synthesizedand their optical properties investigatedboth in solution and when incorporated into a solid matrix. Recognizing the versatility of BODIPY derivatives and the increasing interest in developing new luminescent organic dyes embedded in polymers, the BODIPY derivatives were dispersed into two types of polymeric matrices: Poly(methyl methacrylate) (PMMA) and Thermoplastic Polyurethane (TPU), both as films and microparticles. This resulted in eight new BODIPY-doped polymer films and eight types of BODIPY-doped polymeric microparticles for use in aqueous solutions. The integration of the BODIPY dyes into the polymeric matrices combines the unique properties of the polymer films, such as porosity, flexibility, and elasticity, with the excellent photophysical characteristics of the BODIPYs. Importantly, the dispersion minimized issues such as aggregation-caused quenching commonly observed in solid-state luminescent materials. The thermometric responses of all polymer films were evaluated by studying their solid-state emission spectra in the 25-200°C temperature range. The reversibility of these temperature-induced changes was also assessed, revealing excellent recovery of luminescence. These promising results suggest these materials could have applications as fluorescent thermometric sensors. Furthermore, we explored the potential of the brominated (BDP3) and chalcogenated (BDP4) BODIPY derivatives as ammonia sensors. The two derivatives produced yellow fluorescent products upon interaction with the analyte. Kinetic studies using solid-state emission spectra of BDP4@TPU and BDP4@PMMA showed significant differences in reaction rates (minutes for BDP4@TPU and hours in the case of BDP4@PMMA) attributable to the higher permeability of TPU when compared with PMMA. Detection and quantification of ammonia concentration were conducted by means of simple photographic analysis, measuring the "R" (red) and "G" (green) components of RGB color parameters. Theresults from the photographic method correlated well with the results from fluorimetric spectroscopy studies. The photographic analysis is straightforward, portable, and does not require expensive equipment. Finally, we successfully applied polymeric microparticles doped with BODIPYs to detect ammonia in water, demonstrating their effectiveness without the need for organic solvents. This highlights their potential for environmental monitoring and other applications requiring sensitive and selective detection methods.

Impact of molecular configuration on the photoluminescence and electrical characteristics of poly-pyrrol-thiazol-imine polymers films.

The optical, photoluminescence, and electrical properties of Poly(Z)-PTI and Poly(E)-PTI, two Poly-Pyrrol-Thiazol-Imine polymers with comparable chemical structures but distinct configurations, were examined. Using the dip-casting method, polymer films were deposited on ITO substrates. UV-VIS spectroscopy revealed that both polymers diverged between 500 and 800nm, showing the impact of molecular arrangement, but showed similar absorption behavior for wavelengths shorter than 500nm. For Poly(Z)-PTI, the direct optical energy gaps were 2.06eV, while for Poly(E)-PTI, they were 1.78eV. Poly(Z)-PTI displayed an emission peak at 610nm (red) according to laser photoluminescence spectra, while Poly(E)-PTI peaked at 563nm (green-yellow). The capacitance behavior was revealed by electrochemical impedance spectroscopy. Nyquist plots suggested an equivalent circuit model of Rs (CRct)(QR)(CR) for both polymers, and the relaxation times were 15.9 ns for Poly(Z)-PTI and 89.5 ns for Poly(E)-PTI. The Mott-Schottky analysis verified the n-type conductivity, revealing 2.18 × 1016 cm- 3 carrier densities for Poly(Z)-PTI and 1.78 × 1016 cm- 3 for Poly(E)-PTI. At lower frequencies, both polymers exhibited limited conductivity and large dielectric constants. Insights into the possible uses of Poly-Pyrrol-Thiazol-Imine polymers in electrical and optoelectronic devices are provided by this study, which emphasizes the influence of molecular configuration on these polymers' characteristics.

Effect of silver nanoparticles in polyethylene packaging on physicochemical, microbiological, and textural properties of oil cake.

This study investigated silver nanoparticle (SNP)/titanium dioxide polyethylene films as chemical preservative substitutes to increase the shelf life of oil cake. The research examined three types of packaging films: standard low-density polyethylene (LDPE), LDPE with 3% SNP, and LDPE with 5% SNP, and assessed their impact on oil cake shelf life. Analysis of packaging films included scanning and transmission electron microscopy (SEM and TEM), and Fourier-transform infrared spectroscopy. The study evaluated the effects of SNP on chemical and microbial stability on oil cakes in different storage days (1st, 15th, 30th, and 37th days) at 25 °C. Parameters such as moisture content, water vapor permeability, water activity, peroxide, fat acidity, texture, and microorganisms were studied. The results demonstrated that SNP-containing films can extend the shelf life of oil cake up to 37 days, marked by a significant decrease in microbial growth, particularly mold, compared to conventional packaging films. Notably, films with 5% SNP concentrations exhibited the highest efficacy in preserving the quality of the oil cake. Higher concentrations of SNP led to an increased reduction in microbial load and enhanced mold control while maintaining favorable quality assessment indices throughout the storage period from day 1 to day 30. Remarkably, oil cake packaged with a 5% SNP polymer film displayed the most promising outcomes, extending shelf life up to 30 days at 25 °C.

Plasticizer Design Principle of "Like Dissolves Like": Semiconductor Fluid Plasticized Stretchable Fully π-Conjugated Polymers Films for Uniform Large-Area and Flexible Deep-Blue Polymer Light-Emitting Diodes.

Physical blending of fully π-conjugated polymers (FπCPs) is an effective strategy to achieve intrinsically stretchable films for the fabrication of flexible optoelectronic devices, but easily causes phase separation, nonuniform morphology and uncontrollable photo-electronic processing. This may cause low efficiency, unstable and nonuniform emission, and poor color purity, which are undesirable for deep-blue flexible polymer light-emitting diodes (FPLEDs). Herein, a "Like Dissolves Like" design principle to prepare semiconductor fluid plasticizers (SFPs) is established and intrinsically stretchable FπCPs films via external plasticization for high-performance deep-blue FPLEDs are developed. Three fundamental requirements are proposed, "similar conjugated skeleton, similar molecular polarity, and similar electronic structures," to prepare model-matched nonpolar M1 and polar M2 plasticizers for poly(9,9-dioctylfluorene) (PFO). Large-area plasticized PFO films exhibit an efficient, narrowband, and stable ultra-deep-blue electroluminescence (FWHM < 40nm, CIE: 0.12, 0.04), uniform morphology, and excellent intrinsic stretchability (fracture strain >20% and crack-onset strain >120%). Efficient and uniform deep-blue FPLEDs based on stretchable PFO films are fabricated with a high brightness of ≈3000cd cm-2. Finally, blended PFO films exhibit outstanding stretch-deformation cycling stability of their deep-blue electroluminescent behavior, confirming the effectiveness of the "Like Dissolves Like" principle to design matched SFPs for stretchable FπCP films in flexible electronics.

Nanofiltration Membrane with Enhanced Ion Selectivity Based on a Precision-Engineered Ultrathin Polyethylene Supporting Layer.

Nanofiltration (NF) technology is increasingly used in the water treatment and separation fields. However, most research has focused on refining the selective layer while overlooking the potential role of the supporting layer. With expertise in ultrathin polymer films, particularly in the production of polyethylene (PE) membranes, we explore the possibility of improving NF membrane performance by precisely controlling the structure and surface properties of the ultrathin supporting layer in this work. Here, we introduced an innovative NF membrane that used a submicrometer ultrathin PE membrane produced through a biaxial stretching process, which is significantly thinner than commercial PE membranes available on the market. The core innovations are as follows: first, we focused on precise control of the supporting layer rather than just the selective layer, achieving significant enhancements in overall NF membrane performance; second, the ultrathin PE supporting layer served as a tunable interface for interfacial polymerization, offering possibilities for structural control of the selective layer and advancing membrane performance innovations. The resulting NF membrane boasts an overall thickness of ∼630 nm, which represents the thinnest NF membrane documented to date. This ultrathin NF membrane showed an ultrahigh Cl-/SO42- selectivity of 338.03, placing it at the forefront of existing literature. This study sheds light on the important role of the supporting layer in the preparation of selective layers. We believe that this approach has the potential to contribute to the development of ultrathin, high-performance NF membranes.

Developing Hydration Maps of Polymer Latex Film Formation Using Terahertz Time-Domain Spectroscopy.

The dynamics of the drying process of polymer latexes after casting as a wet film onto a substrate are important to track as they influence the physical and mechanical properties and performance of the dried polymer films. Current methods used to follow this drying process include gravimetric analysis, coupled with advanced techniques like GARField-NMR or optical coherence tomography. The latter two methods provide height and spatial information in the z-direction, normal to the substrate, and occasionally in the xz- or yz-planes. Terahertz time-domain spectroscopy (THz-TDS) is a welcome addition as it provides both the structural and spectroscopic information in the parallel xy-plane, filling the geometric gap. Herein, we utilize THz-TDS to study the drying and film formation process of various polymer latexes with a broad range of glass transition temperatures. We showcase the applicability of this technique in obtaining 2D parallel hydration maps of the drying dispersions, in the form of droplets, using latex-dependent calibration lines. Our findings display known phenomena arising from the drying of the colloidal dispersions.

Delocalized Polarons in Diketopyrrolopyrrole‐Based Conjugated Polymers: Implications for Near‐Infrared Electrochromism and Beyond

AbstractConjugated polymers with delocalized polarons and near‐infrared (IR) absorption properties are promising materials for applications in electrochemical devices. However, the poor stability of low bandgap polymers in electrochemical redox conditions limits the realization of such devices. Herein, a new family of near‐IR absorbing conjugated polymers based on diketopyrrolopyrrole (DPP) derivatives with methoxy substituents to achieve reversible p‐type electrochemical doping with bistable near‐IR electrochromism is designed. The extent of volumetric doping in various electrolytes using cyclic voltammetry and spectroelectrochemistry for optimal electrochemical kinetics and near‐IR contrast is systematically investigated. Further, the spray‐coated films of polymers display high open circuit memory as the methoxylation is increased on the polymer backbone. The contrasting electrochromic memory and kinetics observed for these polymers are mainly ascribed to two factors; i) the effect of backbone structure on the spatial extent of polaron delocalization, and ii) the ionization energy of the polymers. The utility of DPP‐based polymers as energy‐efficient electrochromic optical attenuators (EVOAs) with high near‐IR coloration efficiencies, and an optical attenuation value of 5.1 dB at 1.3 and 1.5 µm wavelengths is demonstrated. Furthermore, the experimental findings are corroborated with theoretical studies to establish that the polaron delocalization length is central to the performance of the device.

Enhanced Electrocaloric Effect of PVDF-based Polymer Composite with Surface Modified AlN.

Poly(vinylidenefluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) relaxor ferroelectric polymer exhibits a modest electrocaloric effect (ECE) at a low electric field near room temperature and a low thermal conductivity. The low thermal conductivity causes poor heat transfer when the terpolymer is used as a cooling device, even when the ECE of the polymer is substantial. By incorporating aluminum nitride (AlN) nanoparticles, which possess high thermal conductivity and good electrical insulation properties, into polymer matrices, we can enhance both the thermal conductivity and the ECE. However, weak bonding at the AlN-polymer interface can lead to a reduced breakdown electric field. Therefore, surface modification of AlN nanoparticles is performed to strengthen the chemical bonding between AlN and the terpolymer, thereby increasing the breakdown electric field. Following the addition of surface-modified nanoparticles, the breakdown electric field of the composite films remained around 240 MV/m, which is comparable to that of the pristine polymer film. Furthermore, the ECE and thermal conductivity were improved by 44% and 55%, respectively. We found three factors influencing the ECE, including the interface effect, the change in ferroelectric-paraelectric phase transition behavior, and the Joule heating effect. To assess the interfacial effect on the ECE, composite films with AlN particles of four different sizes were prepared. It was found that as the size of the nanoparticles increased, which resulted in a decreased interface area, the ECE decreased correspondingly. This finding further confirms the significant impact of the interface area in the composites on the ECE.

Fabrication of amorphous lamellar freestanding poly(N‐dodecyl acrylamide) films and their mechanical properties

AbstractAn amorphous lamellar freestanding film composed of poly(N‐dodecyl acrylamide) (pDDA) was prepared by annealing a micrometer‐thick film under humid conditions (humid‐annealing). pDDA was blade‐coated onto a glass substrate, and its lamellar formation was studied by XRD and polarized optical microscopy (POM). The XRD pattern indicates that pDDA formed a highly oriented lamellar structure by humid‐annealing at 80 °C for 6 h. Moreover, the POM image of the cross‐section of the film indicates that lamellar formation started at the polymer–substrate interface, and the amorphous lamella covered the entire film area without randomly oriented regions. In contrast, the open Nicol microscopic image exhibited large cracks in the highly oriented film owing to shrinkage of the film. A crack‐free film was prepared using water‐saturated chloroform as the solvent for blade coating. Water is thought to adsorb to an amide moiety to induce a ‘pre‐lamellar’ structure in the solution. The formation of pre‐lamellae and the decrease in the humid‐annealing temperature reduced the shrinkage of the film by lamellar formation to form a crack‐free film. The mechanical properties of the crack‐free, freestanding pDDA films were studied using a simple tensile test. The film became increasingly stronger with the formation of an amorphous lamellar structure. These results indicate that the mechanical properties of polymer films can be improved without crystallization. © 2024 The Author(s). Polymer International published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry.

Does the substrate and a buffer layer have a greater influence on poly(3-Hexylthiophene) films deposited by the chronocoulometry technique?

Abstract In this study, we investigate the interface morphology and optical properties of electrochemical poly(3-hexylthiophene) (P3HT) films deposited by electrochemical synthesis using the chronocoulometry technique on tin-doped indium oxide (ITO) and fluorine-doped tin oxide (FTO) and how the substrate used influences in the deposition of the films and their optical and morphological properties, as well as the buffer layer and the interface effect, with and without spin-coating films of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). P3HT polymeric films were synthesized and deposited via the oxidation of the 3-hexylthiophene (3-HT) monomer and characterized via Raman spectroscopy. The morphology and thickness of the P3HT layer present in the samples ITO/P3HT, FTO/P3HT, ITO/PEDOT:PSS/P3HT, and FTO/PEDOT:PSS/P3HT were carried out using atomic force microscopy (AFM). The optical and electronic gap energy of P3HT were calculated from UV‒Vis spectra and cyclic voltammetry curves, respectively. The photoluminescence (PL) spectra showed broad and asymmetrical line shapes fitted by multi-Gaussian functions identifying different emission species. Emission ellipsometry spectroscopy was performed to study the energy transference between adjacent polymer chains. Our results show a higher linear polarized light emitted by ITO/PEDOT:PSS/P3HT film, ∼37%, thus demonstrating a significant decrease in the energy transfer. Based on these results, the efficiency of organic solar cells can be improved via the interaction of the polymer/polymer interface.

Tailoring Wetting Ridge Dynamics on Hybrid Acrylic Polymers: The Impact of Mechanical Properties on Continuous Wetting.

This study examined the relationships among the wetting speed, the polymer mechanical properties, and the resulting deformation characteristics of various graft copolymers synthesized from acrylic monomers and acrylated l-lactide and ε-caprolactone macromonomers (MMs). The mechanical properties of the polymer films were manipulated with minimal impact on their static contact angles with water by varying their MM composition. The focus was on wetting speeds prior to the onset of stick-slip behavior, where ridges were smoothly pulled over the surfaces, thereby producing a transient deformation indicative of a wave pulse. The height of the propagated ridge structures quickly converged to a steady-state value, depending on the wetting speed and polymer properties, regardless of the initial size. The results show that the propagated ridge height correlates with the wetting speed, and the data are well fitted by the Kelvin-Voigt model, which yields two key parameters: the maximum ridge height at the limit of zero velocity and the characteristic wetting speed. Both parameters correlated linearly with the lactide content in the MMs, and the characteristic wetting speed correlated linearly with crossover frequencies from the rheological master curves of the polymers. Furthermore, the characteristic wetting speed was correlated with the peel force required to remove polymer films from the steel plates, establishing a connection between dynamic wetting and adhesive behavior. Our findings shed light on the interdependence between the material composition, mechanical properties, and wetting behavior. The insights presented offer significant potential for designing materials with controlled wetting properties, particularly for applications where capillary flow and surface interactions play critical roles.

Randomizing polarization of displays for fundamental improvement of color mura caused by birefringence.

Most existing displays utilize polarization technologies to produce images and improve image quality. However, polarized light from displays causes color mura because of the birefringence of the polymer films used. Thus, eliminating color degradation remains a challenge despite the incorporation of complex polarization technologies such as retardation films. Our proposed random depolarization film (RDF) addresses this issue by randomizing the polarization of light from displays. Chromaticity measurements demonstrate that the RDF effectively compensates for color mura due to low-cost polymer films. Notably, the RDF compensation mechanism is independent of the RDF position and light source spectrum. Therefore, the RDF could be an innovative solution for color degradation in existing displays.

Increasing the Content of Edge-On Orientation to Improve the Hole Mobility of IDTBT Film by the van der Waals Interaction between the Side Chain and Alkane Additives.

The molecular orientation in the conjugated polymer film critically impacts the performance of organic electronic devices. As for organic field-effect transistors (OFETs), the edge-on orientation is beneficial for efficient interchain charge transport. However, for the near amorphous indacenodithiophene-co-benzothiadiazole (IDTBT) film, the face-on orientation was dominated in the drop cast thin film. Herein, we proposed a strategy to increase the edge-on orientation in IDTBT films by inserting n-hexadecane (16C) additives with a high boiling point between the side chains. Because the 16C additives had a similar structure to that of the side chain, the 16C additives were distributed around the side chain in the nucleation stage. Then, the backbone aggregated quickly with the nuclei formation speed (k) nearly twice as high as that without the 16C additives. In the growth stage, some face-on nuclei turned to edge-on nuclei due to the van der Waals interactions between the side chain and 16C additives. This was verified by the results of in situ GIWAXS, where the intensity of (010) decreased and the intensity of (100) increased in the out-of-plane direction. The edge-on orientation content of the film with 16C additives reached 57%, higher than that of the neat film (33%). Moreover, compared to the neat IDTBT film, the lamellar packing distance of the film with 16C additives increased the lamellar packing distance from 16.97 to 23.26 Å and the π-π stacking distance decreased from 4.36 to 4.19 Å. The hole mobility of the film with 16C additives (3.24 ± 0.19 cm2 V-1 s-1) was higher than that of the neat film (0.94 ± 0.07 cm2 V-1 s-1).

Piezoelectric polymer generators: The large bending regime

There is an important difference between piezoelectric polymer films and solid crystals for the application of piezoelectric generators. In the case of polymers, the optimal piezoelectric response imposes a large bending regime. Starting from the linear Curie’s constitutive equations, we develop an analytical model under the assumption of the large bending regime resulting from bulge testing configuration. This model shows a specific non-linear piezoelectric response, which follows a power of 2/3 of the mechanical excitation. The piezoelectric voltage and the corresponding power are then studied experimentally as a function of the angular frequency ω of the mechanical excitation, the load resistance R, and the thickness of the film ℓ. The experimental results carried out on piezoelectric polyvinylidene fluoride (PVDF) films validate the model.

Antipolyelectrolyte Response of Amphiphilic Sulfobetaine Polymer Coatings

AbstractZwitterionic, amphiphilic polymer coatings are an effective strategy to decrease biofouling. Yet their performance strongly depends on the mechanical properties, the degree of swelling, and the structure of the swollen hydrogels. These properties depend on the zwitterionic groups in the polymers and the properties of the surrounding electrolyte. Therefore, the influence of the ions present and their concentrations on the swelling behavior of amphiphilic zwitterionic copolymers is studied. Coatings of 3‐[N‐2′‐(methacryloyloxy)ethyl‐N,N‐dimethyl]‐ammoniopropane‐1‐sulfonate (SPE) with increasing amounts of butyl‐methacrylate (BMA) are compared to the respective homopolymers PSPE and PBMA. Surface plasmon resonance spectroscopy shows a salt concentration‐dependent anti‐polyelectrolyte behavior. A variation of the salts revealed that the anions dominated the swelling response, while a change of cations has hardly any effect. Small angle X‐ray scattering reveals the morphological changes in the polymer films that accompanied the swelling. With increasing salt concentration, the internal structure changed from compact pores in a gel‐like network to elongated cylindrical pores at higher salinities. The understanding gained from the presented multi‐technique approach allows to understand the behavior of zwitterionic coatings in saline solutions and helps to tailor the swelling response and mechanical properties for future marine and medical low‐fouling applications.

In situ Monitoring of Photocatalysis on Polymeric Carbon Nitride Thin Films.

Polymeric carbon nitride has attracted significant interest in heterogeneous photocatalysis due to its activity under visible-light irradiation. Herein, we report on using carbon nitride-coated NMR tubes for in situ studies of photocatalytic reaction mechanisms. In a first step, we exploited carbon nitride-coated crimp vials as batch photoreactors for visible photocatalytic fluorinations of unactivated C(sp3)-H bonds, with moderate to excellent yields and reusability over multiple cycles. Eventually, carbon nitride-coated NMR tubes were used as a photoreactor by coupling them with optical fiber irradiation directly inside the spectrometer. This enabled us to follow the reaction with in situ NMR spectroscopy identifying reactive intermediates otherwise elusive in conventional analyses. The method provides advantages for the study of photocatalytic mechanisms of complex reactions and substantially reduces the need of comparative tests for depicting reaction intermediates and conversion pathways.

Hydrosilane‐Functionalized [2.2]Paracyclophane for Plasma‐Etch‐Resistant and Post‐Modifiable Poly(Para‐Xylylene)

AbstractPoly(para‐xylylene)s (PPXs), or so‐called parylenes, have become a well‐established polymer class in the conformal coating industry. Due to their transparent nature, low electrical conductivity, and high biocompatibility, they are ideal candidates for coating medical devices and other delicate electronics. However, the crosslinking of PPXs to enhance their durability is still challenging today. Expensive setups need to be used to obtain crosslinked PPXs. Furthermore, the possibility of functionalization post‐polymerization is limited. In this work, we present the synthesis of a hydrosilane functionalized [2.2]paracyclophane, which is used to obtain the corresponding hydrosilane functionalized poly(para‐xylylene) (PPX‐SiH). Through the formation of siloxane bonds during the low‐pressure chemical vapor deposition (LP‐CVD), which increases internal bonding, PPX‐SiH is obtained as a flexible and durable polymer film. The siloxane formation during the LP‐CVD is investigated through X‐ray photoelectron spectroscopy (XPS), nuclear magnetic resonance spectroscopy (NMR), and Fourier‐transform infrared spectroscopy (FTIR). Additionally, mechanistic insights into the formation of siloxane bonds are given through quantum chemical calculation. The Si‐H bonds in the polymer allow for oxidation to form bridging siloxane moieties which enhances stretchability while also increasing the resistance to organic solvents. Through the passivation of the surface during oxygen plasma treatment, PPX‐SiH becomes practically plasma‐etch‐resistant.

Mathematical Modeling and Optimization of Enzyme‐Based Amperometric Screen‐Printed Biosensors Using Horseradish Peroxidase as a Model

AbstractIn this study, a mathematical model was formulated to characterize the functioning of third‐generation enzyme‐based amperometric biosensors. This study utilized a horseradish peroxidase (HRP)‐based, screen‐printed biosensor. The model parameters were determined using the Environment for Modeling Simulation and Optimization (EMSO), validated with experimental data, and exhibited high determination coefficients, indicating the accuracy of the models in capturing biosensor behavior. Simulations based on this model emphasize diffusion as a limiting factor. Further sensitivity analysis was conducted using simulated response surfaces and biosensor performance optimization, which confirmed that higher concentrations of HRP in the thinnest polymeric film resulted in enhanced biosensor sensitivity.

Fabrication of Long-Lasting Superhydrophilic Anti-Fogging Film Via Rapid and Simple UV Process.

Surface fogging is a common phenomenon that can result in restricted visibility, reduced light absorption, and image distortion. Although both hydrophobic and hydrophilic surfaces are effective in preventing this phenomenon, typical coatings in both have limitations, including low durability and the need for frequent reapplication. To address these issues, a highly durable anti-fogging film that lasts over five weeks, even under high moisture conditions, while maintaining a promising degree of transparency (> 60%) is developed. A novel statistical random copolymer containing superhydrophilic and photo-crosslinkable segments that can be simultaneously crosslinked and chemically bonded to various substrates via a simple ultraviolet (UV) irradiation process is synthesized. Notably, the chemical bonding between the anti-fogging coating and substrate improves not only the durability but also the resistance to external forces and environmental changes. Furthermore, this film is versatile and applicable to diverse substrates, such as car windshields, polymer films, and aluminum foil. The innovative strategy offers a simple, rapid process and durable anti-fogging performance with broad applications in the automotive industry, optical devices, and building materials.

Spatially selective actuation of liquid-crystalline polymer films through two-photon absorption processes

Soft materials that respond to external stimuli are promising candidates for next-generation actuators with human-friendly nature1,2. Among various stimuli to induce strain, light offers spatial selectivity, which allows versatile motion of a continuous body. However, spatial selectivity of photoactuation has been limited in two dimension due to the predominant absorption of photons by chromophores near a light source in accordance with Beer-Lambert law. Here, we report the deformation of crosslinked liquid-crystalline polymer films triggered by two-photon absorption. The films containing azotolane moieties show photoinduced deformation upon irradiation with fs laser pulses through two-photon absorption. The direction of photoinduced bending is controlled by depth-selective excitation with a focused laser beam. Furthermore, the mode of deformation is transformed from bending to twisting by irradiating spots near an edge of the film. Inhomogeneous photoirradiation with high spatial selectivity allows an infinite variation of three-dimensional motions even apart from preprogrammed behavior, which would be advantageous especially in application to microactuators.