Density multiplication of patterned templates by directed self-assembly (DSA) of block copolymers (BCP) stands out as a promising alternative to overcome the limitation of conventional lithography. Using the 300mm pilot line available in LETI and Arkema’s materials, the main objective is to integrate DSA directly into the conventional CMOS lithography process in order to achieve high resolution and pattern density multiplication at a low cost. Thus we investigate the potential of DSA to address contact and via level patterning by performing either CD shrink or contact multiplication. Our approach is based on the graphoepitaxy of PS-b-PMMA block copolymers. Lithographic performances of block copolymers are evaluated both for contact shrink and contact doubling. Furthermore, advanced characterization technics are used to monitor in-film self-assembly process. These results show that DSA has a high potential to be integrated directly into the conventional CMOS lithography process in order to achieve high resolution contact holes.

The advantage of magnetic resonance imaging (MRI) is mainly the direct visualization of the physico-chemical processes occurring during the polymer dissolution in real time. Nowadays, polymeric matrices as a means to control the release of the active pharmaceutical ingredient (API) are widely used. Hence it seems necessary to describe the polymer swelling and find the relationship between the type of used polymer and the dissolution profile of API.

The aim of our research was to monitor the dissolution kinetics of polymeric matrices with the different ratio of hydrophilic and lipophilic components utilizing MRI technology. For this purpose, six different matrices were prepared. For the dissolution experiments in MRI magnet, plastic flow through cell and tablet holder were designed and manufactured using a 3-D printer. The experiments were performed under specific conditions i.e. phosphate buffer saline pH 6 as a medium, medium temperature - 37°C, the flow rate of medium - 4 ml/min, the time of experiment - 8 hours. To improve the visibility of the erosion front, composite magnetic nanoparticles SiO2/FeOx as a MRI contrast agent were used. Each matrix was measured three times and the thickness of gel layer was evaluated in three different regions. Results from MRI experiments were compared to the results obtained by utilizing the texture analyzer, and then the relationship between polymer swelling and drug release was evaluated.

To sum up, MRI turned out to be a suitable imaging method for polymer swelling quantification. For the future measurements, the effect of different additives on the polymer swelling kinetics will be evaluated. The results from the whole research should lead to the database of matrix components and conditions of technological processes and their effects on the dissolution profile of API, thus simplifying the formulation of dosage forms with the desired drug release.

ZnO thin films were synthesized by radio-frequency (RF) magnetron sputtering of high purity ZnO solid targets on sapphire substrates. Depositions were carried out at selected temperatures between 293 K and 1173 K, and post-deposition annealing was performed at 1173 K for 3 min. in an O2 atmosphere. Samples for electron microscopy investigations were prepared by lift-out technique in a multi-beam FIB/SEM instrument. The ZnO thin films show generally uniform thickness (about 1µm), determined by transmission electron microscopy (TEM) imaging. Irrespective of the deposition temperature, the ZnO thin films are polycrystalline, with individual grains exhibiting columnar morphology with the long axis oriented perpendicular to the ZnO/sapphire interface. The grain size varies with the deposition temperature, and a direct correlation between grain size and photoluminescence has been observed. Analyses performed using low-temperature photoluminescence spectroscopy measurements at 12 K revealed luminescence peaks at 3.361, 3.317, 3.218 and 3.115 eV. The intensity of the luminescence peak at 3.317 eV decreased with increasing deposition temperature. The films deposited at lower temperatures also exhibited a higher density of stacking faults as observed from the atomic resolution TEM. The crystallographic imperfections/photoluminescence relationship is not clear. The purpose of this study is to quantify the observed crystallographic imperfections and understand their effect on the photoluminescence of undoped ZnO thin films deposited on sapphire substrates.

Conducting polymers are often employed as coatings on smooth metal electrodes to improve the electrode performance with respect to the signal-to-noise ratio for neural recording, charge-injection capacity for neural stimulation, and inducement of neural growth for electrode-tissue integration. However, adhesion of conducting polymer coatings on metal electrodes is poor, making the coating less durable and the electrical property of the electrode less stable. Moreover, conventional conducting polymers have relative low conductance, preventing their direct use as the electrode and lead material; and they are brittle, making it difficult for flexible neural electrodes to incorporate conducting polymer coatings. We have developed a new polypyrrole/polyol-borate composite film with concurrent excellent electrical and mechanical properties. We further developed a method to fabricate a stretchable multielectrode array using this new material as the sole conductor for both electrodes and leads, in contrast with the conventional approach of incorporating conducting polymers only through coating on non-stretchable metal electrodes. The resulting stretchable polymeric multielectrode array (SPMEA) was stretchable up to 23% uniaxial tensile strain with minimal losses in electrical conductivity. Electrochemical testing revealed the SPMEA’s impressive advantage for recording local field neural potentials and for epimysial stimulation of denervated skeletal muscles. As a neural interface engineer, I would also like to compare the compliant neural interfacing technology to other technologies, such as optogenetics, radiogenetics, and even a living neural interface that is currently under development in our lab.

Computation has become an increasingly important tool in materials science. Compared to experimental research, which requires facilities that are often beyond the financial capability of primarily-undergraduate institutions, computation provides a more affordable approach. In the Physics Department at Eastern Illinois University (EIU), students have opportunities to participate in computational materials research. In this paper, I will discuss our approach to involving undergraduate students in this area. Specifically, I will discuss (i) how to prepare undergraduate students for computational research, (ii) how to motivate and recruit students to participate in computational research, and (iii) how to select and design undergraduate projects in computational materials science. Suggestions on how similar approaches can be implemented at other institutions are also given.

In this work, Na- and K-doped β-Li5AlO4 samples were synthesized, characterized and analyzed thermogravimetrically (dynamically and isothermally), under different CO2 conditions. Additionally, chemisorption/desorption cycles were performed for the best chemical compositions and thermal conditions determined. While the CO2 chemisorption of the Na- and K-doped β-Li5AlO4 samples was improved at high temperatures (450 -700 °C), the opposite effect was observed at lower temperatures as well as in the presence of water vapor.

The stability of green phosphorescent OLEDs with different structures was evaluated through constant-current stressing. Through the modifications of the ITO anode by different plasma treatments and the hole transport layer (HTL) by incorporating inorganic dopants, we proved that energy level misalignment at the ITO/HTL interface leads to localized joule heating, accelerating defect generation and luminescence decay. Pulsed current stressing was then employed to suppress the joule-heating effect so as to differentiate the thermal and nonthermal factors governing the device degradation. For OLEDs with a large energy barrier at the ITO/HTL interface, the effective lifetime was markedly increased under pulsed operation, whereas in OLEDs with an appropriate interfacial energy level alignment, pulsed stressing with 10% duty cycle only improved the effective half life by ∼15% as compared to continuous-wave stressing, indicating a minor role played by joule heating.

We report a novel approach for the on-line characterization of nucleation and growth kinetics of lead sulfide (PbS) quantum dots using droplet-based microfluidics. Monodisperse NIR-emitting PbS with optical bandgap between 680 to 1200 nm can be formed rapidly using two reaction schemes at different operating temperatures between 70 and 130°C and the temporal evolution of the absorption and fluorescence spectra are monitored in real-time using a microfluidic platform with an on-line absorption and fluorescence optical system. Therefore, this microfluidic platform is able to provide quantitative information on a millisecond (ms) time frame regarding the size, size distribution, concentration and emission characteristics of the generated nuclei and particles. To our knowledge, this represents the first microfluidic approach for the study of the nucleation and growth in high-temperature colloidal crystallization using in-situ absorption and photoluminescence spectroscopy.

Polymer nanofiber scaffolds for use in neural tissue engineering have been fabricated via electrospinning of poly-L-lactic acid (PLLA) directly onto a 3D printed support. Previously, the investigators have shown success in promoting the directed growth of neural axons on highly aligned PLLA substrates both in vitro and in vivo. However, one criticism of the earlier in vitro studies is that by spinning fibers on a flat, two-dimensional surface, the growth of the axons is restricted to one plane. Thus the axon-to-fiber attachment may not be the sole mechanism for aligning the growth of the axons along the fibers, and the channels between the fibers and the substrate could contribute to the results. Using 3D-printing, elevated or “bridge” spinning stages were made with supports at varying heights, allowing the fibers to be suspended 2 to 5 mm above the substrate surface in different configurations. This 3D structure promotes better access of in vitro cell cultures on the fibers to the growth media during incubation, reduces substrate effects, allows more degrees of freedom for axonal growth, and more closely simulates the growth environment found in vivo. Using these 3D stages, we have electrospun free-standing, highly-aligned pure PLLA fiber scaffolds. We are exploring spinning coaxial fibers with a PLLA sheath and a second core polymer. These coaxial fiber scaffold structures offer additional opportunities for in situ delivery of growth agents and/or electrical stimulation for improved axonal growth results.

Here we present an alternative approach to coarse graining, based on the multiresolution diffusion-wavelet approach to operator compression, which does not require explicit atomistic-to-coarse-grained mappings. Our diffusion-wavelet method takes as input the topology and sparsity of the molecular bonding structure of a system, and returns as output a hierarchical set of degrees of freedom (DoFs) of system-specific coarse-grained variables. Importantly, the hierarchical compression provides a clear framework for modeling at many model scales (levels), beyond the common two-level CG representation. Our results show that the resulting hierarchy separates localized modes, such as a single C-C vibrational mode, from larger-scale motions, e.g., long-range concerted backbone vibrational modes. Our approach correctly captures small-scale chemical features, such as cellulose ring structures, and alkane side chains or CH2 units, as well as large-scale features of the backbone. In particular, the new method’s finest-scale modes describe DoFs similar to united atom models and other chemically-defined CG models. Modes at coarser levels describe increasingly large connected portions of the target polymers. For polyethylene and polystyrene, spatial coordinates and their associated forces were compressed by up to two orders of magnitude. The compression in forces is of particular interest as this allows larger timesteps as well as reducing the number of DoFs.

Modern diffraction and scattering methods of X-ray radiation allow for multi-scale probing of the material morphology for both polymer-based composite films and fibers. These approaches and analyses tools can be used to map the makeup of individual grain structures in various polymer nano-composites in order to examine the effects of the fillers on nano-scale structural changes in the materials. The electron intensity correlation function, derived from Fourier transformations of the X-ray scattering pattern provides a path to analyze acquired data for space resolved domains. Here in this study, polymer-based nano-carbon composite systems are analyzed. The polymers used include polyvinyl alcohol, polyethylene, and polyacrilonitrile as matrix materials. The nano-carbon filler contribution to the grain size evolution is tracked by X-ray scattering/diffraction characterization. These results show that the relevant sizes of crystalline and amorphous domains within the lamellae structures correspond to the dispersion/distribution of the nano-filler in the composite materials. This work mainly illustrates an effective use of the correlation function to provide global morphological analysis in the composite system.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is an organic conducting polymer that has been the focus of significant research over the last decade, in both energy and biological applications. Most commonly, PEDOT is doped by the artificial polymer polystyrene sulfonate due to the excellent electrical characteristics yielded by this pairing. The biopolymer dextran sulphate (DS) has been recently reported as a promising alternative to PEDOT:PSS for biological application, having electrical properties rivaling PEDOT:PSS, complimented by the potential bioactivity of the polysaccharide. In this work we compared chemical and electrochemical polymerisations of PEDOT:DS in terms of their impact on the electrical, morphological and biological properties of the resultant PEDOT:DS films. Post-growth cyclic voltammograms and UV-Vis analyses revealed comparable redox behaviour and absorbance profiles for the two synthesis approaches. Despite good intrinsic conductivity of particles, the addition of chemically produced PEDOT:DS did not markedly enhance the bulk conductivity of aqueous solutions due to the lack of interconnectivity between adjacent PEDOT:DS particles at achievable concentrations. Scanning electron microscopy revealed significantly greater roughness in films cast from chemically produced PEDOT:DS compared to electropolymerised samples, attributable to the formation of solution phase nanoparticles prior to casting. In cell studies with the L929 cell line, electrochemical polymerisation of PEDOT:DS afforded better integrity of resultant films for surface seeding, whilst chemically polymerised PEDOT:DS appeared to localised at the proliferating cells, suggesting possible applications in drug delivery.

Advanced materials with desired wettability are extremely important for environmental sustainability, such as oily industrial wastewater treatment and oil spill cleanup. To meet this demand, a scalable nanoengineering approach was developed to fabricate superhydrophilic and underwater superoleophobic inorganic meshes for cross-flow filtration and oil/water separation. The resulting nanostructured copper meshes exhibit superhydrophilicity and underwater superoleophobicity (oil contact angle approaching to 159°). With these meshes, very high values of filtration flux (≥900,000 Lh-1m-2) have been achieved, with ultra-low oil residue in the filtrate (<40 ppm) and long water retention time (more than 1 h). The proposed nanoengineering method paves the way for effective gravity-driven separation of immiscible oil/water mixtures, especially for low-density oil purification.

This work deals with the effect of the concentration of microsphere of silicon oxide (MS) in SBS-modified asphalt.

A series of blends having 2, 4, 6, 8 and 10 % w/w of MS were prepared from a SBS-modified asphalt having 3 % weight/weight of SBS and known amount of MS. Samples were characterized by fluorescence microscopy, to get an idea of the polymer distribution in the blend; and by conventional tests such as penetration, soft point, density and viscosity, to investigate on the thermo-mechanical resistance of such a blends. It was observed that an increase in the MS resulted in a decreased of the soft point and density, an increased the viscosity, and did no affect the penetration of the sample. Therefore, it was concluded that SBS-MS-modified asphalt is an interesting material for producing polymer-modified asphalt layers.

In this work we introduce an optimization–based method for the coupling of nonlocal and local diffusion problems. Our approach is formulated as a control problem where the states are the solutions of the nonlocal and local equations, the controls are the nonlocal volume constraint and the local boundary condition, and the objective of the optimization is a matching functional for the state variables in the intersection of the nonlocal and local domains. For finite element discretizations we present numerical results in a one–dimensional setting; though preliminary, our tests show the consistency and efficacy of the method, and provide the basis for realistic simulations.

The continuous trend of achieving more complex microelectronics with smaller nodes yet larger wafer sizes in microelectronics manufacturing lead to aggressive development requirements for chemical mechanical planarization (CMP) process. Particularly, beyond the 14 nm technology the development needs made it a must to introduce high mobility channel materials such as Ge. CMP is an enabler for integration of these new materials into future devices. In this study, we implemented a design of experiment (DOE) methodology in order to understand the optimized CMP slurry parameters such as optimal concentration of surface active agent (sodium dodecyl sulfate-SDS), concentration of abrasive particles and pH from the viewpoint of high removal rate and selectivity while maintaining a defect free surface finish. The responses examined were particle size distribution (slurry stability), zeta potential, material removal rate (MRR) and the surface defectivity as a function of the selected design variables. The impact of fumed silica particle loadings, oxidizer (H2O2) concentration, SDS surfactant concentration and pH were analyzed on Ge/silica selectivity through material removal rate (MRR) surface roughness and defectivity analyses.

Nuclear reprocessing plants in Japan produce radioactive iodine-bearing materials such as spent silver adsorbents. Japanese disposal plans classify radioactive waste containing a given quantity of iodine-129 as Transuranic Waste Group 1 for spent silver adsorbent or as Group 3 for bitumen-solidified waste, and stipulate that such waste must be disposed of by burial deep underground. Given the long half-life of iodine-129 of 15.7 million years, it is difficult to prevent release of iodine-129 from the waste into the surrounding environment in the long term. Moreover, because ionic iodine is soluble and not readily adsorbed, its migration is not significantly retarded by engineered or natural barriers. The release of iodine-129 from nuclear waste therefore must be restricted to permit reliable safety assessment; this technique is called “controlled release”. It is desirable that the release period for iodine be longer than 100,000 years. To this end, several techniques for immobilization of iodine have been developed; three leading techniques are the use of synthetic rock (alumina matrix solidification), BPI (BiPbO2I) glass, and high-performance cement. Iodine is fixed as AgI in the grain boundary of corundum or quartz through hot isostatic pressing in synthetic rock, as BPI in boron/lead-based glass, or as cement minerals such as ettringite in high-performance alumina cement. These techniques are assessed by three models: the corrosion model, the leaching model, and the solubility-equilibrium model. This paper describes the current status of these three techniques.