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Drugs with low water solubility comprise a significant proportion of pharmaceutical compounds. To control the release of these drugs, polymer thin‐film formulations with a physical hydrophobic barrier layer do not provide ideal release profiles. In this study, polymer carriers with hydrophilic polyvinyl alcohol (PVA) as the barrier layer are developed, and investigated the effect of the PVA film thickness on the release of hydrophobic molecules. Instead of an aqueous system, an oil‐based system is used to measure membrane permeability, and Nile Red is used as the hydrophobic model drug. PVA thin films are prepared with polycaprolactone as the supportive layer, which retained their permeability. In the limited thickness range investigated, PVA thin films exhibited thickness‐dependent permeability toward the hydrophobic model drug. [ABSTRACT FROM AUTHOR]

Thin films of poly(arylene ethynylene)-conjugated polymers, including low-energy-gap donor–acceptor polymers, can be prepared via stepwise polymerization utilizing surface-confined Sonogashira cross-coupling. This robust and efficient polymerization protocol yields conjugated polymers with a precise molecular structure and with nanometer-level control of the organization and the uniform alignment of the macromolecular chains in the densely packed film. In addition to high stability and predictable and well-defined molecular organization and morphology, the surface-confined conjugated polymer chains experience significant interchain electronic interactions, resulting in dominating intermolecular π-electron delocalization which is primarily responsible for the electronic and spectroscopic properties of polymer films. The fluorescent films demonstrate remarkable performance in chemosensing applications, showing a turn-off fluorescent response on the sub-ppt (part per trillion) level of nitroaromatic explosives in water. This unique sensitivity is likely related to the enhanced exciton mobility in the uniformly aligned and structurally monodisperse polymer films. [ABSTRACT FROM AUTHOR]

In this work, laser‐induced periodic surface structures (LIPSS) are generated on the surface of thin films of poly(trimethylene terephthalate) (PTT) fabricated by spin coating on silicon. Previous studies have shown the appearance of LIPSS in this type of materials with femtosecond laser pulses in the near‐infrared region of the spectrum, despite the extremely low absorption of the polymer. The present work consists of an exploration of the effect of adding complexity to the femtosecond laser fields employed for irradiation. Changes in the repetition rate of the pulse train, the pulse duration, and the pulse temporal chirp are explored, and conditions for optimum LIPSS formation are identified. The effects of these modifications on the polymer surface topography, assessed by atomic force microscopy, are described and discussed. [ABSTRACT FROM AUTHOR]

In this study, we analyze binary and ternary bulk heterojunction organic solar cells utilizing P3HT:ICBA and P3HT:ICBA:DIBSq blends. We investigate optical and electrical properties for different 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (DIBSq) ratios, along with introducing a 140 °C annealing protocol. A comprehensive comparison of optical, electrical, and morphological aspects is conducted between annealed and non-annealed devices. UV-vis measurements unveil expanded near-infrared absorption due to DIBSq. Current–voltage characteristics and external quantum efficiency measurements reveal enhanced performance with increasing DIBSq ratios. Ternary devices achieve 3.96% efficiency with 10.079 mA cm2JSC, 0.83 V VOC, and 0.469 fill factor, compared to binary devices with 2.89% power conversion efficiency, 7.458 mA cm2JSC, 0.795 V VOC, and 0.488 fill factor. Efficiency diminishes beyond a specific DIBSq content. Atomic force microscopy explores morphological properties, showing slight root-mean-square roughness increase and small feature emergence with higher DIBSq concentrations, resulting in suboptimal 5% DIBSq device performance. [ABSTRACT FROM AUTHOR]

Donor‐Acceptor Stenhouse Adduct (DASA), a class of push‐pull negative photochrome, has received large interest lately owing to its versatile synthesis, modularity and excellent photoswitching in solutions. From a technological perspective, it is imperative for this class of photoswitches to work robustly in solid state, e. g. thin films. We feature a molecular framework for the optimized design of DASAs by introducing a new thioindoline donor (D3) and assessing its performance against known 2nd generation indoline‐based donors. The systematic structure‐function investigations suggest that to achieve robust reversible photoswitching, a ground state with low charge separation is desired. DASAs with stronger electron donors and a larger charge separation in the ground state result in a low population of the photothermalstationary state (PTSS) and reduced photostability. The DASA with thioindoline donor (D3A3) seems to be a special case among the donor series as it causes a red shift (ca. 15 nm), however with less polarization of the ground state and marginally better photostability as compared to the unsubstituted 2‐methyl indoline (D1A3). We also emphasize the consideration of the key additional factors that can modulate the red‐light photoswitching properties of DASA chromophores in polymer thin films, which might not be dominant in homogenous solution state. [ABSTRACT FROM AUTHOR]

Applications in soft, flexible optical, and optoelectronic applications demand polymer thin film coatings that can accommodate substantial physical deformations. The preparation of high refractive index polymers (HRIPs) through the quaternization of poly(4‐vinylpyridine) (P4VP) thin films with (di)halomethanes is presented. P4VP thin films are prepared by initiated chemical vapor deposition (iCVD) and then quaternized through exposure to saturated vapors of iodomethane (CH3I), dibromomethane (CH2Br2), and diiodomethane (CH2I2), resulting in refractive indices (RI) as high as 1.67, 1.71, and 2.07, respectively (at 632.8 nm). Fourier‐transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS) confirmed the quaternization of pyridine pendant groups on the polymer chain to n‐methylpyridinium with primarily an iodide or bromide counterion, though a minor fraction of polyiodides are also detected. Additionally, these films demonstrate superior thermal stability, retaining their refractive index and thickness after thermal excursions to 200 °C. The halogenated P4VP films exhibit superior mechanical flexibility relative to conventional inorganic coatings (Al2O3 and Ta2O5) and do not fracture at uniaxial tensile strains as high as 10%. This new material chemistry and fabrication approach method may enable advanced optical designs and functionality in a wide range of substrates and device architectures. [ABSTRACT FROM AUTHOR]

Impact of polymer chain architecture on the swelling of supported single‐layer polymer thin films with thicknesses below 80 nm in the presence of supercritical CO2 (scCO2) is investigated using in‐situ neutron reflectivity (NR) and ex‐situ x‐ray reflectivity (XR). 4‐arm star and 8‐arm star deuterated polystyrene (dPS) having similar total molecular weights are used. NR results revealed that the magnitude of the swelling for star polymers increases proportionally with decreasing dry film thicknesses similar to linear polymers. For film thicknesses above 5Rg, architectural differences have no impact on the swelling behavior. However, below 5Rg as the branching increases from linear to 4‐arm star and to 8‐arm star, swelling decreases due to the presence of a relatively thicker adsorbed layer formed by more branched architectures. Ex‐situ XR measurements verified that star architectures swell less than linear architecture and provided new information about the vitrification of the films through rapid quenching and its relation to the amount of CO2 retention. [ABSTRACT FROM AUTHOR]

Ellipsometry is widely used to determine the thermo-optical properties of thin polymer films. However, if the thermo-optic coefficient (TOC) and the linear thermal expansion coefficient (LTEC) are to be used to determine the temperature coefficient of electronic polarizability (TCEP) in thin polymer films, their values must be determined with the greatest possible accuracy, as both have the opposite effect. In this article, we analyze changes in ellipsometric parameters resulting from changes in the thin film temperature in order to develop a data analysis method for temperature-dependent spectroscopic ellipsometry that will facilitate the accurate determination of thermo-optical parameters, including the TCEP, in polymer thin films. As practical application examples, we identified optimal spectral windows to accurately determine the thermo-optical parameters of 50 to 150 nm-thick PMMA thin films deposited on Si and SiO2 substrates. The influence of thin-film thickness on the accuracy of TOC and LTEC determination is discussed. [ABSTRACT FROM AUTHOR]

The use of nanomaterials is a modern trend in electrochemical analysis because of the ease and accuracy of the analysis that, in addition, being non-destructive to the samples, gives the possibility of repeating the analysis to obtain better results. In this research, films of a co-conductive polymer of pyrrole and one of its derivatives are fabricated by docking on a graphite substrate. The film and the substrate form a modified electrode described by EIS and CV in the presence and absence of valsartan. Using a modified electrode, the concentration of valsartan is determined in titres and blood samples of patients with a standard deviation (SD-0.6). The quantitative and detection limit are LOQ-6 µM and LOD-1.8 µM, respectively. DPV with standard addition method has standard deviation (SD-0.34). The new method succeeds in being more accurate with LOQ-3.4 µM and LOD-1.1 µM, respectively. F-test proves that the HPLC method is not better than DPV and DPV with modified standard addition methods in determining the drug concentration of valsartan. The modified standard addition method is probably the best. [ABSTRACT FROM AUTHOR]

Thin polymer coatings are used to improve the interface between biological species and functional materials. Their interaction is significantly influenced by the functional groups and roughness of the polymer film and prediction of the interaction is thus of great interest. However, for conventional polymer films, this cannot be examined independently because of the interplay of defects, residual solvent molecules, roughness, and functional groups. Solvent‐free polymer films prepared by initiated chemical vapor deposition (iCVD) exhibit conformal, defect‐free characteristics and enable precise tailoring of the functional groups. This facilitates to isolate the contribution of functional groups on the bio‐interface performance. Consequently, in silico studies can enable a prediction of ligand interaction in anti‐viral activity for SARS‐CoV‐2 based on defined polymer and key protein structures. Furthermore, the cell viability of human fibroblasts can be traced back to the functional groups of the repeating units. For human liver cancer cell culture, it turns out that more sophisticated models are needed. The insilico‐iCVD approach can enable precise tailoring of complex polymer films optimized for the respective interfaces. In addition, this first big scan of the bio‐interface performance of iCVD films enables a solid starting point in areas like anticancer, antiviral, and biocompatibility for future studies. [ABSTRACT FROM AUTHOR]

Abstract Thin polymer coatings are used to improve the interface between biological species and functional materials. Their interaction is significantly influenced by the functional groups and roughness of the polymer film and prediction of the interaction is thus of great interest. However, for conventional polymer films, this cannot be examined independently because of the interplay of defects, residual solvent molecules, roughness, and functional groups. Solvent‐free polymer films prepared by initiated chemical vapor deposition (iCVD) exhibit conformal, defect‐free characteristics and enable precise tailoring of the functional groups. This facilitates to isolate the contribution of functional groups on the bio‐interface performance. Consequently, in silico studies can enable a prediction of ligand interaction in anti‐viral activity for SARS‐CoV‐2 based on defined polymer and key protein structures. Furthermore, the cell viability of human fibroblasts can be traced back to the functional groups of the repeating units. For human liver cancer cell culture, it turns out that more sophisticated models are needed. The insilico‐iCVD approach can enable precise tailoring of complex polymer films optimized for the respective interfaces. In addition, this first big scan of the bio‐interface performance of iCVD films enables a solid starting point in areas like anticancer, antiviral, and biocompatibility for future studies.

Abstract Aggregation‐induced emission has eliminated the problem of fluorescence quenching in the solid state, making molecules with this property excellent candidates for vapor sensing due to their portability and ease of interpretation. Here, films of polystyrene / 2‐[4‐vinyl(1,10‐biphenyl)‐40‐yl]‐cyanovinyljulolidine copolymers are reported that exhibit aggregation‐induced emission behavior for the detection of toluene, m‐xylene, dichloromethane, and chloroform. After exposure to the analytes, the emission of the copolymers shows significant changes in intensity and spectral shape corresponding to the reduced microviscosity of the molecular environment. However, these changes are similar for different analytes, resulting in low chemical selectivity. Therefore, label‐free selectivity is achieved by controlling the molecular diffusion of the four vapor analytes within the films using the Flory–Huggins solution theory with capping layers of cellulose acetate (CA) and poly(vinyl alcohol) (PVA) polymers.

In this study, an organic bulk heterojunction (BHJ) solar cell with a spiro OMeTAD as a hole transport layer (HTL) and a PDINO as an electron transport layer (ETL) was simulated through the one-dimensional solar capacitance simulator (SCAPS-1D) software to examine the performance of this type of organic polymer thin-film solar cell. As an active layer, a blend of polymer donor PBDB-T and non-fullerene acceptor ITIC-OE was used. Numerical simulation was performed by varying the thickness of the HTL and the active layer. Firstly, the HTL layer thickness was optimized to 50 nm; after that, the active-layer thickness was varied up to 80 nm. The results of these simulations demonstrated that the HTL thickness has rather little impact on efficiency while the active-layer thickness improves efficiency significantly. The temperature effect on the performance of the solar cells was considered by simulations performed for temperatures from 300 to 400 K; the efficiency of the solar cell decreased with increasing temperature. Generally, polymer films are usually full of traps and defects; the density of the defect (Nt) value was also introduced to the simulation, and it was confirmed that with the increase in defect density (Nt), the efficiency of the solar cell decreases. After thickness, temperature and defect density optimization, a reflective coating was also applied to the cell. It turned out that by introducing the reflective coating to the back side of the solar cell, the efficiency increased by 2.5%. Additionally, the positive effects of HTL and ETL doping on the efficiency of this type of solar cells were demonstrated. [ABSTRACT FROM AUTHOR]

To select the appropriate polymer thin films for liquid oxygen composite hoses, the liquid oxygen compatibility and the cryogenic mechanical properties of four fluoropolymer films (PCTFE, ETFE, FEP and PFA) and two non-fluoropolymer films (PET and PI) before and after immersion in liquid oxygen for an extended time were investigated. The results indicated that the four fluoropolymers were compatible with liquid oxygen before and after immersion for 60 days, and the two non-fluoropolymers were not compatible with liquid oxygen. In addition, the cryogenic mechanical properties of these polymer films underwent changes with the immersion time, and the changes in the non-fluoropolymer films were more pronounced. The cryogenic mechanical properties of the two non-fluoropolymer films were always superior to those of the four fluoropolymer films during the immersion. Further analysis indicated that the fundamental reason for these changes in the cryogenic mechanical properties was the variation in the crystalline phase structure caused by the ultra-low temperature, which was not related to the strong oxidizing properties of the liquid oxygen. Analytical results can provide useful guidance on how to select the appropriate material combination to obtain a reasonable liquid oxygen composite hose structure. [ABSTRACT FROM AUTHOR]

HCl doped-copolymer of ortho phenylene diamine, meta phenylene diamine, and pyrrole terpolymers blend was synthesized. Physical vapor deposition was used to produce the terpolymer-blended thin films, allowing the creation of the fiber structure at a low deposition rate, with a chamber pressure of 5 × 10−5 mbar and a thickness of 100 ± 2 nm. The produced thin films of terpolymers blend were examined utilizing a combination of theoretical and experimental techniques including TD-DFT/DMol3, CATSTEP, FT-IR spectrum, XRD, and optical characterizations. According to XRD computations, the terpolymers blend had an average crystallite size of 190 ± 2 nm, while SEM measurements showed that the length of the fibers was ≅ 73 ± 2 μm. The blend of terpolymers displayed an absorbance of 1.83 at 612 nm. Additionally, the blend of terpolymers' indirect/direct bandgap and absorption index was observed with noticeable alterations. The molecular structure optimization and frequency calculations for the crystal models and isolated molecules were carried out using the materials studio 7.0 tool (TDDFT/DMol3 and CASTEP). The DFT-Gaussian09W-vibration values closely matched the experimental results in terms of structure and optical characteristics. The application of thin films in polymer solar cell applications looks promising due to the noticeable improvements in optical characteristics.

Polymer materials have been widely studied due to their large potential of application in technological fields because of their excellent and diverse properties. Morphological and rearrangement state of synthesized polymers has significant effect on their physicochemical properties and influence the performance of these materials in thin films structures. It is of both fundamental and practical importance to understand the effect of synthesis parameters and changing such parameters on optical, electronic, electrical and morphological properties of polymer surfaces and thin films for the development of new functional polymers and their applications. In this article, the fundamentals of optical, charge career and morphological mechanics are presented for quantifying the use of synthesis parameters for thin films physicochemical properties tuning. Pyrrole with 2-nitrocinnamaldehyde based copolymers have been synthetized by varying synthesis parameters such solvent, reaction time and temperature which proved a relevant effect on the morphological and optoelectronic properties of the relative final deposited thin films. The study proved that the best opto-electric properties are obtained by using either acetone with a long reaction time or chloroform with a short reaction time and room conditions for the pressure and reaction temperature. The optimized PPNC thin films showed a narrow absorbance covering the entire visible optical spectrum and a considerable conductivity of 10.3 104 S/cm ensured by a charge mobility of 677.1 cm2/Vs. The electrochemical study proved that the electronic energy level could be optimized from the synthesis parameters as well as the gap varying around 3.0 eV depending on the optimal conditions. [ABSTRACT FROM AUTHOR]

HCl doped-copolymer of ortho phenylene diamine, meta phenylene diamine, and pyrrole terpolymers blend was synthesized. Physical vapor deposition was used to produce the terpolymer-blended thin films, allowing the creation of the fiber structure at a low deposition rate, with a chamber pressure of 5 × 10−5 mbar and a thickness of 100 ± 2 nm. The produced thin films of terpolymers blend were examined utilizing a combination of theoretical and experimental techniques including TD-DFT/DMol3, CATSTEP, FT-IR spectrum, XRD, and optical characterizations. According to XRD computations, the terpolymers blend had an average crystallite size of 190 ± 2 nm, while SEM measurements showed that the length of the fibers was ≅ 73 ± 2 μm. The blend of terpolymers displayed an absorbance of 1.83 at 612 nm. Additionally, the blend of terpolymers' indirect/direct bandgap and absorption index was observed with noticeable alterations. The molecular structure optimization and frequency calculations for the crystal models and isolated molecules were carried out using the materials studio 7.0 tool (TDDFT/DMol3 and CASTEP). The DFT-Gaussian09W-vibration values closely matched the experimental results in terms of structure and optical characteristics. The application of thin films in polymer solar cell applications looks promising due to the noticeable improvements in optical characteristics. [ABSTRACT FROM AUTHOR]

Replacement of indium tin oxide with the intrinsically conducting polymer poly(3,4–ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been of significant interest in recent years as a result of lower processing and material costs. In addition, the inclusion of additives has been reported to further enhance the conductivity, rheology, and wettability of PEDOT:PSS. In this study, Tween 80 was shown to decrease the sheet resistance of PEDOT:PSS films from approximately 1000 to 76 Ω□−1 at a 2.67 wt% surfactant concentration. Through X-ray diffraction, Raman spectroscopy, and atomic force microscopy, it was shown that the surfactant caused phase separation and structural ordering of the PEDOT and PSS components, leading to this improvement in conductivity. Furthermore, Tween 80 altered the rheological properties and decreased the surface tension of PEDOT:PSS, making coating common commodity polymers, often used as flexible substrates, more viable. [ABSTRACT FROM AUTHOR]

Highly charged ions are a well-known tool for the nanostructuring of surfaces. We report on the thickness dependence of nanostructures produced by single 260 keV Xe38+ ions on ultrathin poly(methyl methacrylate) (PMMA) films (1 nm to 60 nm) deposited onto Si substrates. The nanostructures induced by slow highly charged ions are rimless craters with a diameter of around 15 nm, which are roughly independent of the thickness of the films down to layers of about 2 nm. The crater depth and thus the overall crater volume are, however, thickness-dependent, decreasing in size in films thinner than ~25 nm. Our findings indicate that although the potential energy of the highly charged ions is the predominant source of deposited energy, the depth of the excited material contributing to crater formation is much larger than the neutralization depth of the ions, which occurs in the first nanometer of the solid at the projectile velocity employed here. This suggests synergism between kinetic and potential-driven processes in nanostructure formation in PMMA. [ABSTRACT FROM AUTHOR]

In this paper, the aqueous copolymer dispersions of methyl (meth)acrylate-grafted poly(vinyl alcohol) are in situ synthesized and studied as a promising platform for the deposition of thin films with advanced applications. A series of dispersions of the varied copolymer structure and composition are obtained at mild reaction conditions by carrying out a redox polymerization at a different monomer-to-PVA ratio and initiator concentration. The obtained colloidal particles are characterized by Fourier transformed infrared spectroscopy, nuclear magnetic resonance, dynamic light scattering, and transmission electron microscopy. The copolymer dispersions are further used for deposition of thin films on silicon substrates. The films are characterized optically through reflectance measurements and non-linear curve fitting. Their suitability for the optical sensing of acetone vapors is confirmed by reflectance measurements before and during their exposure to analyte vapors. The cross sensitivity, sensing repeatability, and recovery of the sensitive films are discussed. [ABSTRACT FROM AUTHOR]

Polymer thin‐film sensors have attracted considerable attention in various applications owing to their highly transparent, flexible, and gas‐permeable features. However, conventional thin‐film sensors based on nanomaterials suffer from poor selectivity in sensing targets and scalability of functions. Therefore, a new approach is required for achieving higher selectivity with simple processibility. This study proposes highly transparent, ultra‐flexible, and gas‐permeable polymer thin‐film sensors using ion gels as the sensing material; the sensors demonstrated the capacity for selective detections. Particularly, this study demonstrates simultaneous and independent sensing of temperature and humidity as a proof of concept. The sensors are fabricated using a simple spray coating method on a thin silicone rubber film (≈25 µm thickness). Owing to their thin‐film shape, the sensors exhibit more than 80% visible light transmittance and a higher gas permeability than the human transepidermal water loss. The temperature and humidity are simultaneously detected with a high sensitivity of 15.4% °C–1 and 2.0% per percentage of the relative humidity, respectively, using gels containing two different ionic liquids (ILs). The results suggest that the easily modifiable nature of ILs enables the fabrication of ultra‐flexible and transparent sensors that can detect various objects using a simple method. [ABSTRACT FROM AUTHOR]

• SFG revealed the interfacial structural evolution of PS under confinement. • The penetration of the PS chain at the d 8 -PS/PMMA interface occurred at ∼423 K. • The molecular ordering/orientation evolved during the penetration. • The tilt angle of the phenyl group increased while the twist angle decreased. The geometrical confinement directly affects many crucial properties of polymer thin films by interfacial interactions. A key to understanding the role of these interfacial interactions is to specifically probe the confined interface at the molecular level and in situ. However, the direct and nondestructive detection of interfacial polymer structures under confinement is very difficult. In this study, specific interface-sensitive sum frequency generation (SFG) spectroscopy was applied to study the deuterated PS (d 8 -PS) film confined between hydrogenated poly (methyl methacrylate) (PMMA) films at the molecular level and in situ. The results showed that the ordering/orientation of the PS chain (backbone and phenyl group) evolved at the buried d 8 -PS/PMMA interface during annealing. The tilt angle of the PS phenyl group increased while the twist angle decreased with elevated annealing temperature. Both overall SFG ssp and ppp intensities decreased after annealing at 433 K for 24 h, indicating that PS chains entangled with or penetrated the PMMA chains at the confined interface. This study qualitatively and quantitatively revealed the interfacial structure and structural evolution of the PS chain confined between PMMA films in situ during annealing, which is beneficial to the molecular-level understanding of the interfacial chain conformational relaxation of polymers under confinement. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] We hypothesize that varying the chemical structure of the monomeric unit in a polymer will affect the surface structure and interfacial molecular group orientations of the polymer film leveraging its response to solvents of different chemical affinities. Poly (2-methoxy ethyl methacrylate) and poly (2-tertbutoxy ethyl methacrylate) thin films exposed to either deuterated water (D 2 O) or deuterated chloroform (CDCl 3) were studied by sum frequency generation (SFG) spectroscopy, contact angle goniometry, and atomic force microscopy (AFM) at the polymer-solvent interface, supported with molecular simulation studies. SFG spectral analysis of the polymer thin films corroborated molecular re-organization at the surface when exposed to different chemical environments. The AFM height images of the polymer surfaces were homogeneously flat under CDCl 3 and showed swollen regions under D 2 O. Following the removal of D 2 O, the exposed areas have imprinted, recessed locations and exposure to CDCl 3 resulted in the formation of aggregates. The chemical affinity and characteristics of the solvents played a role in conformational change at the polymer surface. It had direct implications to interfacial processes involving adsorption, permeation which eventually leads to swelling, deformation or aggregation, and possibly dissolution. [ABSTRACT FROM AUTHOR]

This article presents a review on highly thermostable polymer nanocomposites containing silica, based on author’s own researches, placed in a broader context of the published literature. Thin films based on various polymer matrices, using different alkoxysilanes as precursors of inorganic network, were prepared by sol-gel technique. The influence of silica content and of polymer chemical structure on the thermal, electrical and gas separation properties of the resulting films was investigated. Structure-properties relationships which could be used to design new materials with desired physico-chemical characteristics were established.

[Display omitted] Porous polymeric covalent organic frameworks (COFs) have been under intense synthetic investigation with over 100 unique structural motifs known. In order to realize the true potential of these materials, converting the powders into thin films with strict control of thickness and morphology is necessary and accomplished through techniques including interfacial synthesis, chemical exfoliation and mechanical delamination. Recent progress in the construction and tailored properties of thin film COFs are highlighted in this review, addressing mechanical properties as well as application-focused properties in filtration, electronics, sensors, electrochemistry, magnetics, optoelectronics and beyond. Additionally, heterogeneous integration of these thin films with other inorganic and organic materials is discussed, revealing exciting opportunities to integrate COF thin films with other state of the art material and device systems. [ABSTRACT FROM AUTHOR]

Highly charged ions are a well-known tool for the nanostructuring of surfaces. We report on the thickness dependence of nanostructures produced by single 260 keV Xe38+ ions on ultrathin poly(methyl methacrylate) (PMMA) films (1 nm to 60 nm) deposited onto Si substrates. The nanostructures induced by slow highly charged ions are rimless craters with a diameter of around 15 nm, which are roughly independent of the thickness of the films down to layers of about 2 nm. The crater depth and thus the overall crater volume are, however, thickness-dependent, decreasing in size in films thinner than ~25 nm. Our findings indicate that although the potential energy of the highly charged ions is the predominant source of deposited energy, the depth of the excited material contributing to crater formation is much larger than the neutralization depth of the ions, which occurs in the first nanometer of the solid at the projectile velocity employed here. This suggests synergism between kinetic and potential-driven processes in nanostructure formation in PMMA.

Polymers that exhibit aggregation‐induced emission (AIE) find use, for example, as cell‐imaging agents and as fluorometric sensors due to their unique optical properties. However, the structural diversity of AIE‐active polymers has not necessarily advanced at the same rate as their applications. In this work, ring‐opening metathesis polymerization is used to synthesize the first example of a polymer (Mn = 61,600 g mol−1, Đ = 1.32) containing boron difluoride hydrazone (BODIHY) heterocycles in its repeating unit. The BODIHY monomer and polymer described absorb and emit in the visible region in solution (λabs = 428 and 429 nm, λem = 528 and 526 nm) and as thin films (λabs = 443 and 440 nm, λem = 535 and 534 nm). Monomer (ΦFilm = 10%) and polymer (ΦFilm = 6%) exhibit enhanced emission as thin films compared to solution (ΦSoln ≤ 1%) as well as AIE upon the addition of water to DMF solutions as a result of restriction of intramolecular motion. Enhancement factors for the monomer and polymer are determined to be 58 and 15, respectively. The title BODIHY polymer exhibited an earlier onset of AIE and enhanced sensitivity to solution viscosity when compared to the parent monomer. [ABSTRACT FROM AUTHOR]

We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends on both the real and imaginary parts of the atomic scattering factors. Using a model polymer film of poly(styrene-b-methyl methacrylate), we show that the soft x-ray reflectivity data is much more sensitive to these atomic scattering factors than the soft x-ray scattering data. Nevertheless, fits to both types of data yield useful morphological details on the polymer?s lamellar structure that are consistent with each other and with literature values.

• Nickel ferrite (NiFe 2 O 4) powders have been prepared by co-precipitation method and further incorporated into starch grafted acrylic acid copolymer matrix. • By using FTIR, SEM, and VSM to assess the magnetic characteristics, the nanocomposite that was created in this manner was evaluated. • The tensile strength of the starch-grafted methyl methacrylate copolymer matrix is improved to some extent by incorporating Ni ferrites nanoparticles. • The results of the vibrating sample magnetometer (VSM) showed that the fabricated polymer nanocomposite has magnetic properties. A stable nickel ferrite (NiFe 2 O 4) was constructed as incorporated into starch grafted acrylic acid copolymer matrix by co-precipitations followed by annealing. A sample, as annealed at temperature 600 °C, yields a NiFe 2 O 4 of tailored the magnetic properties. The structural, morphological and magnetic properties were investigated by XRD, FTIR, SEM and VSM characterizations. SEM and XRD analysis indicate that particle size in the nano range. In-situ polymerization process was used to insert prepared material with acceptable surface morphology into a starch-grafted methyl methacrylate copolymer. By using FTIR and VSM to assess the magnetic characteristics, nanocomposite was created in this manner was evaluated. Magnetic properties of (NiFe 2 O 4) arise with saturation magnetization M s = 19 em µ g−1. Studies made at room temperature reveals the soft nature of synthesized ferrites. These approaches outcomes demonstrated the material value as a biodegradable thin film with tunable magnetic characteristics that may be used as magnetic strips in future. [ABSTRACT FROM AUTHOR]

The impact of mixer type and critical process parameters (CPPs) on critical quality attributes (CQAs), including the drug content uniformity (CU) of slurry-cast polymer films loaded with micro-sized poorly water-soluble drugs were investigated. Previously untested hypothesis was that the best mixer at suitable CPPs promotes uniform drug dispersion within film precursors leading to acceptable dried-film CU at low, ~0.6 wt% drug concentrations. Taguchi design was utilized to select the best of three mixers; low-shear impeller, high-shear planetary, and high-intensity vibrational, for dried-film drug concentration of ~23 wt%. As-received fenofibrate, a model poorly water-soluble drug (~6 µm) was directly mixed with the hydroxypropyl methylcellulose (HPMC) and glycerin aqueous solution. Impeller and planetary mixers yielded desirable film relative standard deviation (RSD), while vibrational mixer could not. For the lowest dried-film drug concentration of ~0.6 wt%, only planetary mixer yielded RSD

Antifouling/antibacterial coating derived from a sustainable natural resource for biomedical devices have shown promising outcomes, especially in the prevention of bacterial growth. Herein, pulse-plasma chemical vapour deposition is used to fabricate antimicrobial coatings from Terpinen-4-ol, a tea tree oil-based precursor. In this manuscript, during RF plasma polymerisation, pulsed plasma is used to retain the pristine monomer structure in the developed stable coating and thereby enhance its antibacterial activity. The developed films have tunable physical and chemical properties. Diverse film surface properties were obtained by varying the plasma deposition parameters, mainly the deposition mode (pulse and continuous wave) and duty cycle. The role of film wettability on degree of bacterial attachment has been elucidated. Overall, the number of viable bacteria on all the deposited coatings (25–30%) were reduced to half with respect to the control (56%). [ABSTRACT FROM AUTHOR]

Recently, we proposed a surface-controlled cooperative rearranging region (SCC) model that directly predicts the temperature dependence of the cooperativity of segmental dynamics in super-cooled liquids. In this investigation, we employ this model to predict segmental relaxation in polymer ultrathin films. The weighted average of a hole fraction is introduced to account for the cooperativity over segments with different mobilities according to their location in the film. We evaluated the relaxation time for thin films of atactic polystyrene and demonstrated that both the glass transition temperature and the fragility parameter of free-standing and supported films decrease with a reduction of the thickness. This is qualitatively consistent with experimental observations. However, the thickness dependency obtained is weaker compared to that observed experimentally. The origin of this discrepancy is discussed. Image 1 • A new model to predict segmental relaxation in polymer thin films is proposed. • Temperature dependence of the thickness of mobile surface layer is interpreted by the proposed model. • Thickness dependence of glass transition temperature and fragility agrees qualitatively with experimental observations. [ABSTRACT FROM AUTHOR]

Abstract There is a strong demand for development of catalytically active solid substrates for heterogeneous catalysis applications. This study reports fully solution-processable and scalable fabrication of solid substrates decorated with Ag nanostructures for the degradation of organic dyes. Ag nanostructures were prepared by direct surface-growth from Pt nanoparticles that were immobilized on Si substrates modified with a layer of end-grafted poly(2-vinylpyridine). The proper choice of the growth conditions and seed-selective growth from Pt nanoparticles were critically important in fabricating Ag nanostructures with high catalytic activity and large surface coverage. The catalytic performance of the presented platform was studied by the reduction of methyl orange by borohydride ions and monitored using UV–visible spectrometry. The substrates exhibited high catalytic activity enabling degradation of 10−5 M methyl orange solution in less than an hour with an apparent reaction rate constant of 33.5 × 10−3 min−1. The substrates can be easily removed from the degradation medium and used multiple times. Our approach presents an effective strategy for waste water management applications avoiding the agglomeration and separation issues of colloidal catalysts and overcoming the need for tedious and costly fabrication of thin films. [ABSTRACT FROM AUTHOR]

In this work, direct irradiation by a Ti:Sapphire (100 fs) femtosecond laser beam at third harmonic (266 nm), with a moderate repetition rate (50 and 1000 Hz), was used to create regular periodic nanostructures upon polystyrene (PS) thin films. Typical Low Spatial Frequency LIPSSs (LSFLs) were obtained for 50 Hz, as well as for 1 kHz, in cases of one spot zone, and also using a line scanning irradiation. Laser beam fluence, repetition rate, number of pulses (or irradiation time), and scan velocity were optimized to lead to the formation of various periodic nanostructures. It was found that the surface morphology of PS strongly depends on the accumulation of a high number of pulses (103 to 107 pulses) at low energy (1 to 20 µJ/pulse). Additionally, heating the substrate from room temperature up to 97 °C during the laser irradiation modified the ripples’ morphology, particularly their amplitude enhancement from 12 nm (RT) to 20 nm. Scanning electron microscopy and atomic force microscopy were used to image the morphological features of the surface structures. Laser-beam scanning at a chosen speed allowed for the generation of well-resolved ripples on the polymer film and homogeneity over a large area.

Polymer thin films are often used in transdermal patches as a method of continuous drug administration for patients with chronic illness. Understanding the drug segregation and distribution within these films is important for monitoring proper drug release over time. Surface-layer matrix-assisted laser desorption/ionization mass spectrometry imaging (SL-MALDI-MSI) is a unique analytical technique that provides an optical representation of chemical compositions that exist at the surface of polymeric materials. Solvent-free sublimation is employed for application of matrix to the sample surface, so that only molecules in direct contact with the matrix layer are detected. Here, these methodologies are utilized to visualize variations in drug concentration at both the air and substrate interface in pharmaceutical-loaded polymer films. [Display omitted] • Drug-loaded films were prepared from poly(ester urea)-drug blends by casting methods. • The air- and substrate-interfaces of the films were imaged by SL-MALDI-MSI. • SL-MALDI-MSI probes the molecular makeup of polymeric material surfaces (top 2 nm). • Drug coverage at the air-interface increased with drug solution concentration. • When the air-interface became saturated, drug segregated to the substrate-interface. [ABSTRACT FROM AUTHOR]

2D covalent organic frameworks (2D COFs) are attractive candidates for next-generation membranes due to their robust linkages and uniform, tunable pores. Many publications have claimed to achieve selective molecular transport through COF pores, but reported performance metrics for similar networks vary dramatically, and in several cases the reported experiments are inadequate to support such conclusions. These issues require a reevaluation of the literature. Published examples of 2D COF membranes for liquid-phase separations can be broadly divided into two categories, each with common performance characteristics: polycrystalline COF films (most >1 µm thick) and weakly crystalline or amorphous films (most <500 nm thick). Neither category has demonstrated consistent relationships between the designed COF pore structure and separation performance, suggesting that these imperfect materials do not sieve molecules through uniform pores. In this perspective, rigorous practices for evaluating COF membrane structures and separation performance are described, which will facilitate their development toward molecularly precise membranes capable of performing previously unrealized chemical separations. In the absence of this more rigorous standard of proof, reports of COF-based membranes should be treated with skepticism. As methods to control 2D polymerization improve, precise 2D polymer membranes may exhibit exquisite and energy efficient performance relevant for contemporary separation challenges., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Abstract A horizontal neutron reflectometer, Bio-REF, which is dedicated to the structural characterization of polymer and biological thin films and multilayers, has been commissioned at the 30 MW HANARO cold neutron reactor in Korea. The Bio-REF is a hybrid of horizontal and vertical scattering geometries, in which the sample is placed horizontally, and the specular reflectivity is mainly measured by the tilt of sample stage and a wide-range translating detector in θ ‒ 2θ mode. While the horizontal sample setup makes the instrument possible to conduct the measurements on a "free-liquid" system as well as mounting sophisticated sample environments, the θ ‒ 2θ operation allows to maintain the incident beam intensity and, together with the wide translational-length of the detector, the instrument is, therefore, capable of reaching a high Q ∼0.5 Å−1. [ABSTRACT FROM AUTHOR]

Abstract Polymer separators for lithium ion batteries are thin, porous membranes of 20–30 μm thickness. At elevated temperatures, some separators can shrink considerably. To predict the deformation and stresses in the separator in battery cells, it is necessary to measure the expansion/shrinkage property of a separator as expressed by the coefficient of thermal expansion (CTE). The reported CTE measurement techniques for thin films have their limitations. This paper examines the use of a dynamic mechanical analyzer (DMA) for the measurement of the thermal expansion/shrinkage property of polymer separators. The effect of the dimensional change of the testing fixture was considered. The influences of the preloading levels and heating rates were investigated. The measurements were carried out for three common types of polymer based separator. The CTE as a function of temperature was determined from the DMA data. DMA offers continuous measurements in an automatic fashion, which is an efficient and convenient method to characterize the thermal expansion/shrinkage behavior of thin polymer films. Highlights • A calibration was established for the use of DMA in CTE measurement. • The CTE of thin films can be measured continuously in an automatic fashion. • The thermal expansion/shrinkage of three typical separators were investigated. • The CTE relationships for these separators have been established. • Necking/fracture temperature was 15–30 °C lower in TD than in MD. [ABSTRACT FROM AUTHOR]

Abstract: The mechanical properties (e.g., stiffness, stretchability) of prefabricated hydrogels are of pivotal importance for diverse applications in tissue engineering, soft robotics, and medicine. This study reports a feasible method to fabricate ultrasoft and highly stretchable structures from stiff and tough hydrogels of low stretchability and the application of these switchable hydrogels in programmable shape‐morphing systems. Stiff and tough hydrogel structures are first fabricated by the mechanical strengthening of Ca2+‐alginate/polyacrylamide tough hydrogels by addition of Fe3+ ions, which introduces Fe3+ ionically cross‐linked centers into the Ca2+ divalent cross‐linked hydrogel, forming an additional and much less flexible trivalent ionically cross‐linked network. The resulting stiff and tough hydrogels are exposed to an L‐ascorbic acid (vitamin C, VC) solution to rapidly reduce Fe3+ to Fe2+. As a result, flexible divalent ionically cross‐linked networks are formed, leading to swift softening of the stiff and tough hydrogels. Moreover, localized stiffness variation of the tough hydrogels can be realized by precise patterning of the VC solution. To validate this concept, sequential steps of VC patterning are carried out for local tuning of the stiffness of the hydrogels. With this strategy, localized softening, unfolding, and sequential folding of the tough hydrogels into complex 3D structures is demonstrated. [ABSTRACT FROM AUTHOR]

We study the effect of bimodal molecular weight distribution on glass transition of polystyrene (PS) under one-dimensional confinement by employing hot-stage spectroscopic ellipsometry. The bulk PS is found to have an exceptionally low glass transition temperature (T g ) of around 61 °C. This intriguing finding is attributed to the presence of a sizable fraction of very low molecular weight components (∼3000 g/mol). A further suppression of T g compared to the already reduced bulk value is observed upon reduction of the film thickness. We also observe that glass transition width of the bulk PS is broader than its monodisperse counterpart which is further broadened upon confinement. [ABSTRACT FROM AUTHOR]

Abstract: In this paper systematic changes in the isothermal crystallization kinetics (at Tc = 200 °C) of nonequilibrated isotactic polystyrene films, generated through spin coating are reported. Kinetics is tuned by annealing films at Ta = 250 °C, i.e., above their nominal melting temperature (TmDSC = 220 °C). An exponential decrease in growth rate and a significant decrease of crystal nucleation density by approximately three orders of magnitude are observed by increasing the time (ta) provided for equilibration at Ta. The characteristic exponential decay time is approximately four orders of magnitude longer than the equilibrium reptation time at Ta. Interestingly, with increasing ta, a change in the morphology of lamellar crystals varying from spherulites to hexagons of rather uniform height to finally hexagons exhibiting periodic modulations in height is observed. These observations reveal that understanding and tuning the crystallization kinetics of polymer films under quiescent conditions requires knowledge on how strongly chain conformations deviate from equilibrium. [ABSTRACT FROM AUTHOR]