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Mechanical properties and measurements of conjugated polymers have been introduced by Professor Lipomi in volume II. In this chapter, we mainly focus on the materials design principles for conjugated polymers that are mechanically and electronically suitable for stretchable electronics. Thin films of conjugated polymers that present excellent electronic properties are typically mechanically fragile, while polymers that offer excellent deformability and stretchability do not show excellence in electronic properties. The major efforts in search of conjugated polymers for stretchable electronics are to lift this trade-off between their electronic and mechanical properties. There are currently two successful engineering approaches, namely strain engineering and the adoption of nanocomposites (i.e. the nanoconfinement effect). In strain engineering, conjugated polymers are placed onto an elastic substrate to form complex thin film structures that can be reversibly deformable under strain. In the nanocomposites, conjugated polymers are dispersed into elastic matrix polymers. Through the nanoconfinement effect, the blended thin films can present substantially improved stretchability of polymer semiconductors without diminishing their electronic properties (i.e. charge transport mobility). Other than these two engineering approaches, a third approach from polymer chemists aims to minimize the trade-off and design intrinsically stretchable conjugated polymers that meet the needs of both electronic and mechanical requirements. Both side chain and backbone engineering have been demonstrated to be effective in the design of intrinsic stretchable conjugated polymers.

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 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. Keywords: Catalytically active surfaces, Ag nanostructures, Polymer thin films, Catalytic degradation, Methyl orange

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.

Redox-active dithiafulvenyl endgroups were attached to dendritic oligo(phenylene vinylene)s which contain a non-planar, twisted anthraquinodimethane core. The ability of these π-electron rich molecules to bind with nitrobenzene and its derivatives was demonstrated, and their electrochemically generated polymer thin films were tested as efficient sensors for nitrobenzene.

This data file contains the detailed synthetic procedure for the synthesis of two new cyanopyridine based conjugated polymer P1 and P2 along with the synthesis of its monomers. The synthesised polymers can be used for electroluminescence and photovoltaic (PV) application. The physical data of the polymers are provided in this data file along with the morphological data of the polymer thin films. The data provided here are in association with the research article entitled ‘Cyanopyridine based conjugated polymer-synthesis and characterisation’ (Hemavathi et al., 2015) [3].

High fatigue resistance, bistability, and drastic property changes among isomers allow efficient modulation of the current output of organic thin-film transistors (OTFTs) to be obtained by a photogating of the charge-injection mechanism.

Current administration of ranibizumab and other therapeutic macromolecules to the vitreous and retina carries ocular risks, and a high patient treatment burden, and compliance barriers that can lead to suboptimal treatment. Here we introduce a device that produces sustained release of ranibizumab in the vitreous cavity over the course of several months. Composed of twin nanoporous polymer thin films surrounding a ranibizumab reservoir, these devices provide release of ranibizumab over 16 weeks in vitro and 12 weeks in vivo, without exhausting the initial drug payload. Following implantation in vivo, devices were well tolerated and showed no sign of immune response. This platform presents a potential solution to the challenge of delivering protein therapeutics to the vitreous and retina for sustained periods of time.

While an increasing requirement from both fundamental and application, a direct tensile testing of freestanding polymer thin films in the air remains a challenge, mainly due to their extreme fragility. This study aims to establish a facile and reliable testing system, and investigate the effect of specimen geometry on the testing. First, a thin film transfer and adhesive guide frame gripping technique is introduced. With low length-to-width ratio specimens, tensile testing of rectangle non-standard polystyrene films with thickness down to 45 nm is achieved on a commercial universal testing machine. By changing specimen width and gauge length individually, a scale law between system compliance and specimen width is then verified. After corrected by compliance, a constant modulus of ~3.15 GPa for 45–4319 nm thick polystyrene films can be obtained. This study provides a potential strategy to overcome operational difficulties in performing tensile testing of freestanding polymer thin films.

Polymere werden in vielen Bereichen der Beschichtungsindustrie als Schutzschichten verschiedener Materialien verwendet. Bei bestimmten Anwendungen muss das Polymer sch��dlichen Umwelteinfl��ssen, wie beispielsweise UV-Strahlung und korrosiven Gasen (z.B. SO2 und H2S), widerstehen und das darunterliegende Material sch��tzen. Um l��ngerfristig optimalen Schutzeigenschaften zu gew��hren, sollte das Polymer dabei nicht degradieren und das bedeckte Material vor Alterung sch��tzen. Ein Ziel dieser Studie war, die Machbarkeit der Messung von polymerdegradation und Schwefelaufnahme, mittels LIBS (Laserinduzierte Plasmaspektroskopie; engl.: laser-induced breakdown spectroscopy) und LA-ICP-MS (Laserablations-Massenspektrometrie mit induktiv gekoppeltem Plasma), zu testen. Anders als viele heutzutage verwendete Techniken sind diese zwei nicht auf Oberfl��chenanalyse beschr��nkt, sondern erm��glichen es auch, Tiefenprofile aufzunehmen. F��nf verschiedene Polyimid-Filme auf einem Siliziumsubstrat, sowie reines Kupfer, wurden unterschiedlicher korrosiver Umgebung (50ppm SO2 oder H2S f��r 192 h) ausgesetzt und danach mit LIBS und LA-ICP-MS analysiert. Zus atzlich wurden Polyimid-Proben in einer UV-Kammer f��r 96 h mit UV-Licht bestrahlt. Mittels LIBS, in Kombination mit multivariater Statistik, ist es gelungen, durch UV-Licht verursachte Ver��nderungen im Polyimid nachzuweisen. Zus��tzlich wurden Ver��nderungen in der chemischen Zusammensetzung, aufgrund der Entstehung von Korrosionsprodukten auf Reinkupfer, untersucht und gezeigt, dass H2S korrosiver wirkt als SO2. LA-ICP-MS wurde f��r die qualitative Messung der Gaspermeabilit��t in Polyimid optimiert. Die Aufnahme von Tiefenprofilen war erfolgreich. Es wurde herausgefunden, dass die Bewitterung mit SO2 zu einem signifikanten Anstieg der Intensit��t des Schwefelsignals f��hrt. Die Zunahme war im oberen Bereich des Polyimids am h��chsten und nahm zum Substrat hin ab. Die Bewitterung mit H2S resultierte insgesamt in einer kaum messbaren Ver��anderung. Bei zwei der f��nf Polyimide f��hrte UV-Bestrahlung vor der Bewitterung mit H2S zu einem Anstieg des Schwefelsignals in den oberen Lagen des Polymerfilms. Mit LIBS und LA-ICP-MS ist es erfolgreich gelungen, Polymerdegradation und Diffusion in Polymeren zu messen. Diese Ergebnisse legen nahe, dass SO2 einfacher in Polyimid eindringt als H2S und, dass UV-Bestrahlung die Permeabilit��t signifikant beeinflussen kann und zu messbarer Degradation des Polyimids f��hrt., Polymers are used in the coating industry as protective layers for many materials. For certain applications the polymer must withstand and protect the underlying material from harsh environmental conditions such as exposure to UV-radiation and corrosive gases (e.g. SO2 and H2S). To provide optimal protective properties, the polymer should not degrade under these conditions and should prevent alteration of the underlying material. One aim of this study was to test LIBS (Laser Induced Breakdown Spectroscopy) and LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) on their feasibility for measurement of polymer degradation and sulfur uptake. Unlike most currently employed techniques, these two are not limited to the surface but also enable depth profiling. Five different polyimide films on silicon substrate as well as pure copper were weathered in different corrosive atmospheres (50ppm of SO2 or H2S for 192 h) and then analyzed using LIBS and LA-ICP-MS. Additionally polyimide samples were put in a UV chamber and exposed to UV irradiation for 96 h. Using LIBS in combination with multivariate statistics, changes in the polyimide due to UV alteration were successfully observed. Additionally, changes in chemical composition due to the formation of corrosion products on pure copper were analyzed and proved that H2S is more corrosive than SO2. LA-ICP-MS was optimized for the qualitative measurement of gas permeability into the polyimide. The acquisition of depth profiles was successful. It was found that SO2 weathering results in a significant increase in sulfur signal intensity. The observed increase was strongest in the upper part of the polyimde film and decreased towards the substrate. The H2S weathering hardly showed a measurable change at all. For two of the five polyimides UV exposure prior to H2S weathering lead to an increase in sulfur signal in the upper layers of the polymer film LIBS and LA-ICP-MS have successfully been employed for measurement of polymer degradation and diffusion in polymers. The findings suggest that SO2 permeates polyimides more easily than H2S and that UV exposure significantly influences the permeability and leads to observable degradation of the polyimide.

Simulation of X-ray reflectivity (XRR) curves based on standard theoretical formalism has been performed by changing the structural parameters such as thickness, density, and roughness. Analysis of simulated curves shows that the density of thin films can be obtained within the specified range of thickness assuming chemical and physical changes occur in the system. Also along with this simulation, we have performed experimental XRR studies using polymer thin films of different thicknesses prepared by spin-coating method. In-situ XRR data were collected while chemical and structural changes occur in thin films. Results show that the instant density of the films can be determined during chemical and structural changes in the films as observed by comparison with simulated curves.

In recent years, there has been a tendency toward creating innovative, easy to use and patient-friendly drug delivery systems suitable for every consumer profile, which would ensure safety, stability and acceptability of a drug. One of the relatively novel and promising approaches is the manufacture of orodispersible films (ODFs), which is an upcoming area of interest in drug delivery. They are defined as polymer thin films that disintegrate in the oral cavity within seconds, without drinking water or chewing, and eliminate the risk of choking. Gaining special usefulness in therapies of children and the elderly, ODFs seem to fill the gap in the range of preparations available for these groups of patients. As no detailed monography of ODFs including testing methods and uniform requirements has been presented in any of the pharmacopoeias to date, the aim of this article is to give an overview of the applied testing methods, their modifications and innovative approaches related to ODF quality assessment.

How a liquid drop sits or moves depends on the physical and mechanical properties of the underlying substrate. This can be seen in the hysteresis of the contact angle made by a drop on a solid, which is known to originate from surface heterogeneities, and in the slowing of droplet motion on deformable solids. Here, we show how a moving contact line can be used to characterize a molecularly thin polymer layer on a solid. We find that the hysteresis depends on the polymerization index and can be optimized to be vanishingly small (, The characterisation of interfacial layers, whose rheology can differ from the bulk, is important for the design of new materials. Here, Lhermerout et al. use the dynamics of a moving contact line to quantify the mechanical properties of a polymer thin film.

Nesse trabalho foi investigada a modifica??o superficial por irradia??o de ?ons e tratamento t?rmico de filmes finos de PMMA e PVC de diferentes espessuras (entre 2,5 e 290 nm) depositados sobre l?minas de Si. Tr?s condi??es diferentes foram testadas: a) apenas tratamento t?rmico em c?mara de v?cuo em temperaturas entre 80 ?C e 224 ?C por at? 72 h; b) efeito de irradia??o com ?ons de alta energia (H+ de 2 MeV, Au+7 de 17 MeV e Bi+eq de 2,2 GeV) em temperaturas (-196 ?C at? 150 ?C); c) irradia??o com tratamento t?rmico em temperatura entre 80 ?C e 224 ?C com at? 72 h de annealing. A aplica??es de tratamento t?rmico, na maioria dos casos, n?o apresentaram altera??es significativas na rugosidade e porosidade nos filmes com exce??o de T=100 ?C e longos tempos de tratamentos (72 h). Filmes de PMMA e de PVC irradiados com H+ apresentaram alisamento ap?s altas flu?ncias de irradia??o provavelmente associadas ao aumento da mobilidade das cadeias devido ?s cis?es induzidas pela irradia??o. J? as irradia??es de ?ons pesados de Au+7 e Bi+eq aumentaram fortemente a rugosidade dos filmes devido ? elevada eros?o provocada pelos ?ons. A irradia??o com ?ons de Au+7 associadas ? temperatura acima da temperatura ambiente contribuiu para o aumento da rugosidade, formando novos padr?es de defeitos na superf?cie. Quando combinado a irradia??o desses ?ons com a temperatura ocorre uma modifica??o no padr?o das estruturas no filme, com o surgimento maior de ondas com baixa frequ?ncia espacial. Contudo, os efeitos de irradia??es combinados com tratamento t?rmico apresentaram aumento da rugosidade para longos tempos de exposi??o, provavelmente ocasionados pelo aumento da mobilidade do pol?mero com o aumento de temperatura e o tempo. Medidas complementares de ?ngulo de contato indicaram maior molhabilidade para irradia??es com H+, chegando a uma forte diminui??o para ?ons de Bi+eq. Isso se deve ?s fortes modifica??es qu?micas s?o geradas por ambos os ?ons na estrutura do filme. Por fim, foi realizada uma an?lise do m?dulo de elasticidade pelas t?cnicas de nanoindenta??o e AFM para comparar com os dados obtidos entre ambas. As medidas obtidas pelo nanoindentador apresentaram grande influ?ncia do substrato, com valores superiores aos descritos na literatura, ao contr?rio ocorrido com o AFM, na qual apresentou valores similares ? literatura. Os filmes de PVC apresentaram aumento no m?dulo de elasticidade com o aumento da flu?ncia, j? para os filmes de PMMA foi observado um efeito oposto, apresentando um decr?scimo no m?dulo de elasticidade. In this work, the surface modification by ion irradiation and heat treatment of PMMA and PVC thin films with different thicknesses (between 2.5 and 290 nm) deposited on Si wafers was investigated. Three different conditions were tested: a) heat treatment in vacuum chamber with temperatures between 80 ?C and 224 ?C, up to 72 h ; b) high energy ions irradiation (2 MeV H+, 17 MeV Au+7 and 2.2 GeV Bi+eq) at temperatures that varied from -196 ?C to 150 ?C and c) ion irradiation associated with subsequent annealing at temperatures between 80 ?C and 224 ?C in times up to 72 h. Heat treatment by itself, in most cases, did not show any significant changes in the roughness and porosity of the films, save for T = 100 ?C and long treatment times (72 h). PMMA and PVC films irradiated with H+ underwent a smoothing process after high irradiation fluencies, probably because the chain motility was increased by irradiation-induced scission. However, irradiations with Au+7 and Bi+eq strongly increased the roughness of the films due to the high erosion caused by the ions. The irradiation with Au+7 ions associated with temperatures above room temperature contributed to the increase of the roughness, forming new surface defects patterns. When the ion irradiation is combined with the temperature, a modification in the pattern of the structures on the film occurs, with higher occurrence of waves with low spatial frequency. However, the effects of irradiation combined with heat treatment showed roughness increase for long exposure times, probably as a result of the polymer mobility increase with increasing temperature and time. Complementary contact angle measurements indicated higher wettability for H+ irradiations, reaching a strong decrease for Bi+eq ions, this is due to the strong chemical modifications that are generated in the structure of the film by both ions. Finally, an analysis of the modulus of elasticity was performed by nanoindentation and AFM techniques, in order to compare the data obtained by both techniques. The measurements obtained by the nanoindenter data showed great influence of the substrate, with values higher than those described in the literature, contrary to the AFM, in which similar values to the literature were found. The PVC films presented an increase in the elastic modulus with the increase of the fluence, but for the PMMA films the opposite effect was observed, presenting a decrease in the elastic modulus. Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES

We investigate transmission characteristics of a fiber-optic structure based on a fiber section with depressed inner cladding and thin polymer overlays. We measure transmission spectra of the structure upon changes in external refractive index and overlays thickness and compare our results with theoretical calculation. Two types of coatings are studied: polyacrylic acid, which is deposited on the fiber using layer-by-layer assembly technology, and polyvinyl alcohol.

The persistent issue of bacterial and fungal colonization of artificial implantable materials and the decreasing efficacy of conventional systemic antibiotics used to treat implant-associated infections has led to the development of a wide range of antifouling and antibacterial strategies. This article reviews one such strategy where inherently biologically active renewable resources, i.e., plant secondary metabolites (PSMs) and their naturally occurring combinations (i.e., essential oils) are used for surface functionalization and synthesis of polymer thin films. With a distinct mode of antibacterial activity, broad spectrum of action, and diversity of available chemistries, plant secondary metabolites present an attractive alternative to conventional antibiotics. However, their conversion from liquid to solid phase without a significant loss of activity is not trivial. Using selected examples, this article shows how plasma techniques provide a sufficiently flexible and chemically reactive environment to enable the synthesis of biologically-active polymer coatings from volatile renewable resources.

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.

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.

The bottom-up patterning approach provides intrinsic advantages associated with unlimited resolution but is limited by the materials available for selection. A general and simple approach towards the selective deposition of poly-para-xylylenes is introduced in this communication. The chemical vapour deposition (CVD) of poly-para-xylylenes is inhibited on the high-energy surfaces of electrically charged conducting substrates. This technology provides an approach to selectively deposit poly-para-xylylenes irrespective of the substituted functionality and to pattern these polymer thin films from the bottom up.

An intensive gain of surface hydrophobicity has been observed on the differently polar polymer layers spin-coated directly on the previously prepared nanostructured nickel surface to form nanohybrids. Nanostructured nickel layer has been prepared by electrochemical deposition to form polyhedral crystalline nanostructure. Surface morphology and homogeneity of a nanohybrid polymer layer have been monitored by TOF-SIMS and SEM methods. Hydrophobicity extension of nanohybrid surfaces increased nearly linearly with decreasing polarity of single polymers applied and maximum increase in hydrophobicity value obtained was 32%. Novel nanohybrid surfaces functionality has been tested on the different cells adhesion. The results showed cell adhesion followed with an inhibition of the living cells spreading and proliferation on declared nanostructured nickel–polymer nanohybrid surfaces. The maximum inhibition activity of nanohybrid surface against cells line has been observed in a case when polydimethylsiloxane was applied as surface polymeric layer. Preparation of this kind of surface is easy and inexpensive, with many proposed applications where hydrophobic surfaces are required. This also can tend as a model for the preparation of the surfaces with cell anti-adhesion and antimicrobial activity.

Regular changes in ferroelectric and pyroelectric properties of P(VDF-TrFE) polymer thin films were observed when the films have a bent-deformation caused by external force. The deformation rate dependence of the remanent polarization, relative dielectric constant and pyroelectric coefficient of the P(VDF-TrFE) thin films were studied. The results demonstrated that there was an increase of ∼12.2% in the remanent polarization of the bent films between the maximum and the minimum bent-deformation rate. Pyroelectric coefficient of the bent P(VDF-TrFE) thin films was also enhanced compared with the flat P(VDF-TrFE) films. P(VDF-TrFE) films can still maintain good performance in ferroelectric and pyroelectric properties under bent deformation, which is meaningful to the potential application in flexible devices.

The remote release of nano-objects from a container is a promising approach to transduce chemical events into an optical signal. The major challenge in the development of such a system involves the use of a suitable molecular gate that retains aggregated particles and releases them upon applying an external stimulus. We show proof-of-concept experiments for the release of gold nanoparticles into an aqueous solution upon photodegradation of conjugated polymer thin films. Gold nanoparticles thus transduce light-induced chemical events into an amplified optical signal with a release rate of 2.5 nM per hour, which can be readily detected by the naked eye.

Indentation of hydrated Nafion thin films reveals that both the in-plane diffusivity of water and the intrinsic permeability of the phase-segregated network decrease dramatically with decreasing film thickness. Using pore-network theory, this decrease in diffusivity is attributed to both an increase in ionic-domain heterogeneity and a reduction in ionic-domain connectivity upon confinement.

We investigate the glass transition behavior in polymer thin films using a model equation-of-state approach, which involves molecular parameters whose values are determined from fits to bulk information only (pressure–volume–temperature and surface tension data). Following an earlier proof-of-concept application to freestanding polystyrene (PS) films, here we both extend the study to poly(methyl methacrylate) (PMMA) films and generalize the model so that it is applicable for either freestanding or supported films. In the case of the freestanding PMMA film, model predictions for the Tg suppression (relative to bulk) as a function of film thickness are in very good agreement with the corresponding experimental data, reflecting the fact that freestanding PMMA films are evidently less perturbed by the presence of free surfaces than those made of PS. We then turn to the case of PMMA films supported on a silica substrate by accounting for possible polymer–substrate interactions, such that when these are switche...

Summary Surface-initiated Kumada-catalyst transfer polycondensation (SI-KCTP) has become the preferred method for fabricating surface-bound conjugated polymer thin films. Here, the chain-growth character of SI-KCTP is exploited to allow for re-initiation of surface-bound films. Additionally, surface enhanced Raman spectroscopy (SERS) is shown to be a powerful tool in the analysis of surface-bound intermediates.

With the advances in nanotechnology, the glass transition and chain relaxation behavior for polymer molecules in a confined geometry have been attracted great attentions. Due to the nano-scale effects, the molecular dynamics of polymer thin film deviates from that in the bulk, and are a function of the dimension of films (i.e. thickness). The studies of the molecular dynamic in polymer thin film are of significant importance both in term of optimizing the physical properties of polymer nanomaterials and also in the developing our understanding of the nature of glass transition for amorphous materials. In this paper, some important results in the field of the dynamics of thin polymer film are reviewed. We summarized the physical mechanisms responsible for the deviation of chain dynamic from that in bulk, and discussed the distribution of chain mobility in polymer thin film, as well, some theoretical models describing the glass transition of thin polymer film was introduced. In the end, the problems in this field and prospects in the further studies were also discussed.

The role of the materials used for packaging is to protect inner content from external, mostly negative, factors. Besides being safe, and with good mechanical properties, these materials need to align with other consumers’ needs and demands, being both attractive and authentic, while at the same time meeting ecological requirements. Gelatin-based thin films are good candidates for production of semi-soft cup-shaped products that could be used for cruciferous vegetables packaging. These films were prepared by a simple solvent evaporation method. Prepared films were characterized by swelling study and their mechanical properties were investigated. The optical characteristics of the films were determined by optical microscopy revealing that these systems possess attractive clear and transparent gold-yellowish appearance with a smooth surface. Keywords: Gelatin, Glycerol, Chamomile Tea Extract, Polymer Thin Films

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.

The disparate results for Tg shifts in ultra-thin polymer films with the same film thickness, substrate, and chemistry raises the question of whether Tg is a useful way to characterize thin films. Underlying many Tg measurements is the assumption that Tg estimates used for bulk polymer are helpful to infer the dynamical changes in thin films. We use molecular simulations of a coarse-grained polymer film supported on a substrate with variable interaction strength with polymer to test this assumption. As expected, the slowing of polymer dynamics near a highly attractive substrate forms a bound layer that effectively insulates the reminder of the film from strongly interacting substrate. As a result, thermodynamic estimates of Tg is relatively insensitive to the polymer-substrate interaction strength e when the substrate interactions exceed those of the polymer-polymer interactions. Due to this insensitivity, thermodynamically defined measures of Tg decrease with decreasing film thickness, regardless of e. Dynamically defined measures of Tg also decreases with decreasing thickness when e is relatively weak; however, the dynamic Tg increases when e exceeds the polymer-polymer interaction strength. Our results show that these qualitatively different trends in Tg reflect differing sensitivities to the mobility gradient across the film. We emphasize that using single measure of Tg to infer changes in the dynamics of polymer thin films is limited.

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.

The glass transition temperature ( T g ) of poly(α-methyl styrene) (PαMS) films supported by silica is studied as a function of film thicknesses from ~ 17 to ~ 168 nm at three molecular weights of 1.3, 20 and 420 kg/mol. For the 20 and 420 kg/mol films, the glass transition temperature decreases with decreasing film thickness, consistent with previous results. But for the 1.3 kg/mol films, it becomes independent of the film thickness. We tentatively suggest the T g depression to be caused by free volume excess at the polymer–air interface and that its influence diminishes at low enough molecular weights because of a chain stiffness effect.