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Polymer temperature sensors are important for applications in food packaging, air conditioning, wearable devices, and biomedicine. However, the sensing range of these sensors is narrow, and the mod...

An elastic film with water repellency is of great interest for application to waterproof and antifouling surface treatment of stretchable devices such as wearable electronics or functional textiles...

Block polymers (BPs) potentially can be used to template large arrays of nanopatterns for advanced nanotechnologies. However, the practical utilization of directed BP self-assembly typically requires guide patterns of relatively small size scales. In this work, the macroscopic alignment of block polymer cylinders on a template-free substrate is achieved through raster solvent vapor annealing combined with soft shear (RSVA-SS). Spatial control over nanoscale structures is realized by using a solvent vapor delivery nozzle, poly(dimethylsiloxane) shearing pad, and motorized stage. Complex patterns including dashes, crossed lines, and curves are demonstrated, along with the ability for large area alignment and scale-up for industry applications. The unique ability to directly write macroscopic patterns with microscopically aligned BP nanostructures will open new avenues of applied research in nanotechnology.

In this presentation, we will describe our results with field-emission type source and drain contacts in which the metal electrodes are tapered to a sharp point or an array of sharp points. The enhanced electric field as a consequence of this geometry results in more facile injection of charges from the metal to the band states of the semiconductor. The on-resistance of short channel TFTs is lowered and the channel lengths of TFTs can be reduced below 100 nm without adversely affecting the shape of the current-voltage characteristics.

A crucial target in the printed electronics technologies is to realize all-printed thin-film transistors (TFTs), as being applicable to the industry. Here, the authors report printed polymer TFTs through the integration of the SuPR-NaP technique, a promising way for manufacturing ultrafine printed silver electrodes, with printed polymer semiconductor layers. The authors used a class of donor–acceptor-type copolymer, PDVT-10, and found that the devices exhibit excellent TFT characteristics. The devices allow the transfer length method measurements with high accuracy, where the estimated contact resistance is considerably small (4.7 kΩ cm) among the bottom-contact TFTs using printed silver electrodes, with also showing short-channel effects.

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.

Stochastic resonance (SR) phenomenon is emerged in organic field effect transistors (OFETs) using $\pi$-conjugated polymer, where application of external noise to the OFET system enhances signal/information processing performance which is often found in biological systems.The channel conductivity of the OFET is slightly increased by spin-coating using heated semiconductor polymer solution with heated glass substrate.In order to improve frequency responses of OFET, optimal width of the gate electrode is explored. Furthermore, it turns out that scratching and removing semiconductor film outside the source-drain electrodes and the channel enhances the On-Off current ratio of the device. These fabrication processes lead to steeper nonlinearity on the $I_{\rm DS}$ {\it vs.} $V_{\rm GS}$ curve, resulting in emergence of SR, which is fingerprinted in increase of correlation value between input and output signals with increase of intensity of external noise.

Stabilizing ultrathin films, in particular avoiding dewetting, is critical to the application of polymer thin films from biology to electronics. To address this issue, a wide range of approaches ha...

Polymeric-thin-film-based electronic and optoelectronic materials and devices are attractive for potential space and certain radiation-related applications due to their inherent features such as lightweight, flexible, biocompatible, etc. Proton radiation is a major form of ionizing radiation in space, particularly in the so-called inner Van Allen belt region where most near-earth satellites are orbiting, yet very few literature and data are available on proton radiation effects on conjugated polymer systems. In this report, the proton radiation effects on potential electronic/optoelectronic properties of several conjugated polymers and their composites are briefly evaluated. Specifically, UV–VIS absorption spectra of several conjugated polymers and/or their composite thin films were measured and compared right before and after the proton radiations at different dosages. The results revealed that proton radiation has very little or insignificant impact up to 800 rad on the optoelectronic properties...

This paper describes how thin air gaps in multilayer polymer thin film structures can lead to unexpectedly large signals in modulation ellipsometry experiments, which can then be misinterpreted as the electro-optic effect. The contributions from the electro-optic effect and polarisation on reflection from the air cavity are indistinguishable and the reflection contribution can be on the order of 100 times that of the electro-optic effect. Caution must thus be exercised in any attempt to measure electro-optic coefficients with modulation ellipsometry in the presence of air gaps, to avoid spuriously high results. Thin film multilayer structures containing air gaps may be suitable for some of the same applications as electro-optic reflectance modulators.

The possibility to evaluate the molecular diffusivity in polymer thin films used for packaging and device encapsulation directly in-situ would represent a paradigm changer in the assesment of barrier properties and of air quality. Indeed, employing the packaging itself as a smart sensor could lead to waste reduction and mitigate food poisoning effects. In this work, we demonstrate a new technique that exploits simple UV-Vis reflectance spectroscopy to identify the kinetic of diffusion of small molecules in the vapor phase through polymer thin films and polymer multilayered structures. The new method allows then to assess the presence of the analyte in air and its diffusion coefficient in agreement with gravimetric data reported in literature.

Planar photonic components can be fabricated with high resolution by electron beam patterning of polymer thin films on solid substrates such as silicon and glass. However, polymer films are normally formed by spin-coating lithographic resists containing not only polymers but also volatile solvents, which is a serious environmental and health issue. Therefore, we investigate a new type of material for planar structure fabrication (i.e., room-temperature ionic liquids (RTILs) with a polymerizable allyl group) that is electron-beam-curable, solvent-free, and thus potentially interesting for processing materials with weak resistance to solvents. We fabricate planar polymer microstructures by electron beam patterning of RTIL thin films in vacuum, which is possible because of the negligible volatility of ionic liquids. Three different polymerizable ionic liquids {i.e., [Allmim][Cl] (1-allyl-3-methylimidazolium chloride), [Allmim][NTf

A variable-angle spectroscopic ellipsometer (VASE) is an essential tool for measuring the thickness of a thin film, as well as its n and k optical parameters. However, for films thinner than 10 nm, precise measurement is very challenging. In this paper, the root causes of these measurement complexities are discussed, and a new approach is proposed to improve measurement accuracy and reliability as the VASE approaches its fundamental limits, that is, the limitations of the system’s mechanical accuracy and optical coherence. Specifically, twelve different polymer thin films were tested, each with 16 test points. The measured thicknesses (ranging from 3 nm to 19 nm) and n- and k-values strongly depended on test settings and on the data fitting algorithm, incident angle, and wavelength selection. Fitting using equal thickness and n-value of multiple test points was applied as additional criteria to evaluate the consistency of the test results. With this technique, reasonable n-values and thickness values were obtained from films that were as thin as 3 nm. To improve the efficiency of the model fitting, film thickness and n-value are associated to allow these two-dimensional parameters to be fitted into a quasi-one-dimensional model, which reduces central processing unit (CPU) utilization.

There have been many reports of thin-film transistors based on semiconductors with mobilities in the range 1-20 cm2/Vs in the past few decades. The mobilities and mean free paths are simply too low for the application of conventional semiconductor transport theories based on solutions to the Boltzmann transport equation (BTE). We will present a very general solution based on the statistical nature of charge transport and introduction of a factor related to the probability of mean free path exceeding the minimum transport length. We are then able to apply the BTE with appropriate scattering mechanisms and obtain very good results that agree well with experiment. This approach is very well suited to thin-film transistors based on polymer and organic semiconductors with room temperature mobilities in the range 1-20 cm2/Vs. We compare theory with experimental results for DPP-based polymers and also oxides. Charge transport depends on carrier densities and electric fields in complex ways. We describe these dependencies in detail. Scaling down channel dimensions of organic and polymer semiconductor based thin-film transistors to submicron and nanoscale dimensions, required for higher speed operation, presents several challenges. Successful scaling will enable vastly improved device performance and hence the prospects are certainly very enticing. One of the biggest challenges is in making relatively low-resistance contacts. A more thorough understanding of velocity saturation mechanisms and charge transport at high electric fields is also necessary. We describe charge transport in oxide and polymer TFTs with an emphasis on scaling. We show that for some TFTs, scaling of the channel width facilitates scaling down of channel length and a nanostripe or nanogroove array channel geometry has advantages. Finally, we describe hybrid TFTs – with multiple materials that are better suited to scaling down.

Mechano-optoelectronic (MO) behavior indicates changes in optoelectronic properties in response to the applied mechanical deformation. The MO behavior can be employed to monitor the mechanical deformation of a targeted system by tracing its optoelectronic properties. Poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester (P3HT/PCBM) blend thin films exhibited changes in direct current under tensile strain. Although optoelectronic properties and photovoltaic performance of P3HT/PCBM blends have been studied extensively and intensively, research required for MO properties has a fundamental difference from previous research mostly for solar cells. In research for MO systems, a greater extent of changes in optoelectronic properties under mechanical deformation is favorable. Herein, previous research for optoelectronic properties and mechanical properties of conjugated polymers will be reviewed from a perspective on MO properties. The microstructure of a conjugated polymer thin film plays a pivotal role in its optoelectronic properties and mechanical properties. Key parameters involved in the microstructure of conjugated polymer thin films will be addressed. A scalable process is required to broaden applications of MO systems. Potential challenges in the fabrication of MO conjugated polymer thin films will be discussed. Finally, this review is envisioned to provide insight into the design and manufacturing of MO conjugated polymer thin films.

The immense potential of light responsive polymer materials toward technological applications in photonics, mechanics and micro-fabrication has been attracting increasing attention from both materials chemists and physicists. Light can render multifold stimuli to materials via electronic excitation reflecting the directional wave properties at high spatio-temporal resolutions. Due to recent developments in synthesis, polymerization and materialization procedures, the opportunities of photoresponsive design are becoming more and more diversified, resulting in the creation of a wide variety of new photofunctions. Very often, serendipitous phenomena are found, which further facilitate streams of research. When liquid crystalline materials are employed, strongly cooperative events take place, providing attractive non-linear processes. This article introduces very recent topics in these fields mostly focusing on new trends in photo-directed alignment, surface morphing in polymer thin films, and photo-induced motion and deformation of small objects.

In this study, it was aimed to obtain PolyTerpenol thin films by radio frequency plasma enhanced chemical vapor deposition technique using Terpinen-4-ol essential oil, which is organic compounds. The surface morphology and chemical properties of polymer thin films were investigated by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy. AFM analyzes of PolyTerpenol thin films revealed that the thin films are homogeneous, smooth and nonporous. The optical properties of the thin films were determined using UV–Vis spectrophotometer. When optical band gaps of thin films were examined, it was found that this value varied from 3.83 to 3.20 eV. The extinction coefficients of the obtained thin films according to the increasing RF energy were calculated as 0.0011, 0.0060, 0.0085 and 0.0150, respectively, at a wavelength of 320 nm. In addition, antibacterial effects of these thin films against Escherichia Coli (E.Coli) bacteria were also investigated. The PolyTerpenol thin films were found to have high antibacterial activity against E. Coli bacteria. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

This issue of Radiation Physics and Chemistry contains selected papers presented at the 12th Ionizing Radiation and Polymers conference (IRaP 2016) that was held from September 25 to September 30, 2016 at Belambra “Les Criques” in Giens, France. IRaP has the particularity to focus on the effect of ionizing radiations on polymers. This biennial conference was initiated with the three-fold objective to 1) bring together scientists from research centers, universities and industry, 2) provide a forum to exchange knowledge and information in this field and , 3) to promote innovative applications. IRaP 2016 was attended by 125 scientists and 10 accompanying persons from 20 countries. The scientific program consisted of 15 plenary sessions (21 invited and 40 selected lectures), two poster sessions (68 posters), 1 course and 1 keynote. The course, delivered by Emmanuel Balanzat (Caen, France), gave young scientists the opportunity to enlarge their knowledge on the influence of the nature of the projectile on polymer modification, i.e. the specificity of Swift Heavy Ions. The keynote, presented by Pr. Vladimir Feldman (Moscow, Russia), gave a great overview on radiation damage mechanisms at cryogenic temperatures. IRaP2016 in France gave the opportunity to honor the memory of Dr. Natacha Betz, one of the founders of the IRaP conference, for the tenth anniversary of her passing away. In a dedicated tribute, Dr. Serge Bouffard (Caen, France) offered a wealth of insights on her scientific career, testimonials of memorable moments and messages to the polymer irradiation community. IRaP2016 was also the occasion to acknowledge some senior scientists’ contributions. Especially, a special session on gels, devoted to Pr. Janusz Rosiak (Lodz, Poland), was hosted to mark his upcoming retirement. This was an opportunity for his colleagues and friends to congratulate him and to highlight his valuable and remarkable input on the development of hydrogels. Traditional IRaP symposium topics such as fundamental processes, radiation-induced chemical modifications (ageing, degradation, resulting physical properties modification) and their application in the fabrication of advanced materials were addressed. Notably, the nanostructures of polymer thin films through ion-track technology allows the fabrication of interesting advanced polymer-based new materials for sensoring purposes. Radiation-induced grafting technique is still widely developed, using up-to-date polymerization mechanisms (eg. RAFT mechanism), and applied to various industrial fields of interest among which flame retardant materials, energy harvesting or drug delivery systems. It is worth noting that drug delivery devices, combining various radiation-based strategies such as the synthesis of crosslinked nanogels, were widely represented. In addition to synthetic polymers, bio-based and biopolymers were presented as base materials of growing interest. Due to an increasing environmental concern, numerous studies aimed notably at improving the biodegradability of polymers. New sessions (Radiolysis and Lifetime prediction) and new trends (Monte-Carlo calculations for the study of polymer ageing and the association of metal/polymer hybrid nanoparticles for medical applications) have entered the topic list of the 12th IRaP. The present special issue of Radiation Physics and Chemistry gathers the selected articles, peer reviewed by independent referees, among the manuscripts submitted for publication after the conference. The organizing committee gratefully acknowledges all the contributors. We thank the referees for their critical reading of the manuscripts and the associated detailed reviews, ensuring the required standard for RPC. The three guest editors would also like to thank Pr. Laszlo Wojnarovits for his help during the editing process. The success of this 12th edition of the IRaP conference is first assigned to the attendees and the contributors. On behalf of the organizing committee, we would like to thank them for this special issue, the scientific and steering committees for their valuable help in the organization and the local organizing committee (the green team and L. De Baeremaker included) for all the hours of hard work they have pulled to make this conference a great success. We address a special and personal thanks to Dr. Caroline Aymes-Chodur for her precious help all along the conference organization, despite her knowing that she wouldn’t attend the conference. We also thank the staff of the Belambra “Les Criques“ resort, especially Ms. Celine Lacommere for her friendliness and her dedication. All this, added to the gorgeous location and the sunny weather, certainly contributed in the enjoyment of IRaP2016. We would like to acknowledge the institutions, organizations and companies that supported the IRaP 2016: IAEA, IIA (International Irradiation Association), CEA, Andra, CNRS, Universite de Caen, Caen la Mer and Ionisos. Thanks to the support of the IAEA and IIA, eight young scientists, selected on the basis of their scientific work, have been granted to attend the IRaP2016 conference. Finally, we would like to address special thanks to the companies who funded an exhibition booth: AERIAL, NIST, Steris and Thermo Scientific.

Raman imaging is one of the very informative methods for the characterization of chemically and structurally heterogeneous materials without employing specific molecular labels. Multifocus Raman imaging is one of the fast-imaging alternatives to the conventional single point mapping technique. Since multiple focal points probe the sample simultaneously, this imaging methodology is faster compared to single point mapping. We have further demonstrated the efficiency of this methodology by investigating the morphological features of a porous PMMA film. A Raman image of a 50 × 50 μm(2) area was obtained in less than 4 minutes (with a 10 × 10 multifocus configuration). Importantly, a 100 × 100 μm(2) area could now be analyzed in minutes while a similar Raman image by single point mapping would take hours to days. Optical sectioning using multifocus Raman imaging reveals unique hierarchical features of the porous polymer thin film. Larger pores are limited to the surface and the inner bulk exhibits characteristic small-pores and an interconnected highly porous morphology. The fast multifocal Raman imaging would be advantageous to the diverse field of scientific disciplines where the speed of image acquisition remains a challenge despite the unparalleled specificity and sensitivity of Raman spectroscopy.

Single wavelength ellipsometry measurements at Brewster's angle and in multiple incident media provide a powerful technique for characterizing ultrathin (

Poly(quinoxaline-2,3-diyl)s bearing (S)-2-methylbutyl, n-butyl, and 8-chlorooctyl groups as side chains were synthesized to fabricate dry solid polymer thin films. These films exhibited selective reflection of right-handed circular polarized light (CPL) in the visible region after annealing in CHCl3 vapor at room temperature. The handedness of reflected CPL was inverted to the left after annealing in 1,2-dichloroethane vapor. It was also found that the color of a particular single film along with the handedness of reflected CPL were fully tuned reversibly, upon exposure of the film to the vapor of various mixtures of chloroform and 1,2-dichloroethane in different ratios.

The combination of photoacoustic tomography (PAT) with optical coherence tomography (OCT) has seen steady progress over the past few years. With the benchtop and semi-benchtop configurations, preclinical and clinical results have been demonstrated, paving the way for wider applications using dual modality PAT/OCT systems. However, as for the most updated semi-benchtop PAT/OCT system which employs a Fabry-Perot polymer film sensor, it is restricted to only human palm imaging due to the limited flexibility of the probe. The passband limit of the polymer film sensor further restricts the OCT source selection and reduces the sensitivity of the combined OCT system. To tackle these issues, we developed an articulated PAT/OCT probe for both preclinical and clinical applications. In the probe design, the sample arm of OCT sub-system and the interrogation part of the PAT sub-system are integrated into one compact unit. The polymer film sensor has a quick release function so that before each OCT scan, the sensor can be taken off to avoid the sensitivity drop and artefacts in OCT. The holding mechanism of the sensor is also more compact compared to previous designs, permitting access to uneven surfaces of the subjects. With the help of the articulated probe and a patient chair, we are able to perform co-registered imaging on human subjects on both upper and lower extremities while they are at rest positions. An increase in performance characteristics is also achieved. Patients with skin diseases are currently being recruited to test its clinical feasibility.

NREL and RhoTech will collaborate to bring long-lived, ultra-low-cost, high-performance solar water heaters (SWH) to market readiness. An existing RhoTech design uses seam-welded polymer thin films to make an unglazed thermosiphon, and this design will be modified to improve durability through ultraviolet and overheat protection, and to improve performance by adding a glazing to the collector. Two generations of the new glazed systems will be tested in the field, resulting in a robust market-ready SWH design that can be installed for under $1,000 without rebates.

The performance of polymer field effect transistors (FETs) can vary by orders of magnitude by applying different processing conditions. Although it is generally believed that a higher degree of crystallinity results in a higher mobility, the correlation is not straightforward. In addition, the effect of cross-linking on polymer thin film microstructural order is relatively unknown. This study investigates the effect of thermal annealing and UV-initiated photo-cross-linking on the FET performance and microstructural order of a photo-cross-linkable P3HT derivative. Our results demonstrate that while cross-linking did not disrupt the overall crystallinity of the polymer thin film, the photo-cross-linking process likely induced doping in the semiconductor layer, leading to the absence of saturation behavior in the FET. Annealing after cross-linking slightly improved the FET performance but only minimally affected the microstructural order of the polymer film since the 3D morphology had been “locked in” during...

Metallic nanotriangles arranged in a hexagonal lattice are common nanostructures used for surface-enhanced Raman spectroscopy. Such structures, generally made by nanosphere lithography or electron ...

We report X-ray reflectivity measurements of polystyrene thin films supported on Si substrates at various heating and cooling rates. At a heating rate of 0.05 °C min−1, the width of the glass transition w does not show any noticeable thickness dependence. However, at faster (0.5 °C min−1) and slower (0.01 °C min−1) heating rates, w shows remarkable thickness dependence: it broadens at a faster rate and narrows at a slower rate with decreasing film thickness. Our results suggest that the heterogeneous character of the dynamics can be transformed into a homogeneous one in a glassy film with thickness comparable to a critical thickness that depends on the rate of temperature variation. X-ray reflectivity measurements are performed on polystyrene thin films supported on Si substrates at various heating and cooling rates. With decreasing thickness, the width of the glass transition (w) shows an appreciable variation that depends on the rate of temperature variation: broadening at a rate of 0.5 °C min−1, no broadening at a rate of 0.05 °C min−1 and narrowing at a rate of 0.01 °C min−1.

In this paper, we analyze the variation of the threshold voltage V T and carrier mobility μ fet with the active layer thickness of polymer thin film transistors (PTFTs). The value of V T was observed to become more negative as the active layer thickness decrease, while mobility slightly increased. Simulations obtained for different active layer thickness were first validated with experimental data from measured devices with known active layer thickness. Then using the calibrated simulator, it was found that as the semiconductor thickness decreased, the charge per square units in the active layer changes, establishing the cause of both of these behaviors.

The present work demonstrates the first application of Brillouin light scattering to probe elastic excitations in highly anisotropic polymer thin films. Both the in-plane and out-of-plane longitudi...

In 1892 Drude and Nernst reported the first observation of a standing light wave by using a fluorescent thin film, which is a real-time version of Wiener’s first experiment on standing light wave. We reproduce the experiment by Drude and Nernst with improved efficiency using modern laser technology and a highly fluorescent π-conjugated polymer. We also used a glass plate scratched slightly on one surface to visualize the same phenomenon using diffuse reflection instead of fluorescence. This method has the advantage of being a wavelength-independent observation compared to the fluorescence method.

We employ Brillouin light scattering to measure the longitudinal modulus in supported thin polymer films in the direction normal to the film surface. In this first systematic experimental investiga...

In this paper we demonstrated enhancement of photoinduced polarization rotation for improved transmission of laser light at low input intensities through a crossed polarized system. It is achieved by utilizing two azobenzene doped polymer thin films in tandem. As the input beam propagates through the films, its polarization rotation induced by each film is additive. We obtained polarization rotation of as much as 24° resulting in enhanced transmission compared to a single-film approach. In addition, this novel design is promising for use as a broadband nonlinear transmission system.

We have used seven different techniques to measure the anisotropic refractive index of poly(vinylcarbazole) films. These techniques are: two types of variable angle spectroscopic ellipsometry (VASE ...

Force–displacement curves have been acquired with a commercial atomic force microscope on thin films of poly( n -butyl methacrylate) on glass substrates. Different film thicknesses, from 10 up to 430 nm, were chosen to examine in detail the so called “mechanical double-layer” topic, i.e., the influence of the substrate on the determination of the mechanical properties of thin films. Taking advantage of the Hertz theory we calculated for all films the contact radius between tip and sample as a function of the applied load. Further Young's modulus of the samples was derived from the experimental data as a function of the applied load and, alternatively, of the deformation. The results of this analysis for 10 different film thicknesses were fitted with several half empirical equations proposed by several researchers. The focus of this work is to evaluate such existing half empirical theories for mechanical double-layers and to show the need for an alternative consistent approach.