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Ethylcellulose is commonly dissolved in a solvent or formed into an aqueous dispersion and sprayed onto various dosage forms to form a barrier membrane to provide controlled release in pharmaceutical formulations. Due to the variety of solvents utilized in the pharmaceutical industry and the importance solvent can play on film formation and film strength it is critical to understand how solvent can influence these parameters.To systematically study a variety of solvent blends and how these solvent blends influence ethylcellulose film formation, physical and mechanical film properties and solution properties such as clarity and viscosity.Using high throughput capabilities and evaporation rate modeling, thirty-one different solvent blends composed of ethanol, isopropanol, acetone, methanol, and/or water were formulated, analyzed for viscosity and clarity, and narrowed down to four solvent blends. Brookfield viscosity, film casting, mechanical film testing and water permeation were also completed.High throughput analysis identified isopropanol/water, ethanol, ethanol/water and methanol/acetone/water as solvent blends with unique clarity and viscosity values. Evaporation rate modeling further rank ordered these candidates from excellent to poor interaction with ethylcellulose. Isopropanol/water was identified as the most suitable solvent blend for ethylcellulose due to azeotrope formation during evaporation, which resulted in a solvent-rich phase allowing the ethylcellulose polymer chains to remain maximally extended during film formation. Consequently, the highest clarity and most ductile films were formed.Employing high throughput capabilities paired with evaporation rate modeling allowed strong predictions between solvent interaction with ethylcellulose and mechanical film properties.

The fabrication of nanostructured films possessing tricontinuous minimal surface mesophases with well-defined framework and pore connectivity remains a difficult task. As a new route to these structures, we introduce glycerol monooleate (GMO) as a template for evaporation-induced self-assembly. As deposited, a nanostructured double gyroid phase is formed, as indicated by analysis of grazing-incidence small-angle x-ray scattering data. Removal of GMO by UV/O(3) treatment or acid extraction induces a phase change to a nanoporous body-centered structure which we tentatively identify as based on the IW-P surface. To improve film quality, we add a co-surfactant to the GMO in a mass ratio of 1:10; when this co-surfactant is cetyltrimethylammonium bromide, we find an unusually large pore size (8-12 nm) in acid extracted films, while UV/O(3) treated films yield pores of only ca. 4 nm. Using this pore size dependence on film processing procedure, we create a simple method for patterning pore size in nanoporous films, demonstrating spatially-defined size-selective molecular adsorption.

Previously, the synthesis of highly oriented pure double-gyroid nanoporous silica films has been demonstrated using evaporation-induced self-assembly (EISA) and dip-coating with a specialty triblock surfactant (PEO-PPO-alkyl) as the template. For these films, grazing-incidence small-angle X-ray scattering (GISAXS) was used to determine orientation and structure. However, GISAXS is not widely available, and we have observed significant batch-to-batch variability in the PEO-PPO-alkyl surfactants used. Here, we show for the first time: (1) synthesis of highly oriented pure double-gyroid nanoporous silica films using freely available EO(19)-PO(43)-EO(19) surfactant (Pluronic-P84) as the nanostructure-directing agent, (2) the use of spin-coating and dip-coating EISA to fabricate the double-gyroid films, and (3) the use of theta-theta X-ray diffractometers (commonly available and typically used for powder X-ray diffraction, PXRD) to identify the double-gyroid phase. Processing diagrams for P84 using dip-coating and spin-coating are shown in order to map the dependency of the nanostructure on solution composition, relative humidity, and solution aging time. In addition, an effect of the rate of evaporation during EISA is observed via dependence on the angular velocity in spin-coating. Also, through quantitative comparison of the GISAXS patterns with corresponding PXRD patterns, previously unexplained diffraction peaks in the PXRD patterns are shown to result from diffraction from crystallographic planes that are not parallel to the substrate (typically not observed in PXRD) due to the small angles involved and the nonzero acceptance angle of the PXRD Soller slits. These peaks provide a means to distinctly identify the double-gyroid phase using PXRD. The same trends relating aging-time-before-coating to the phase that forms via EISA are observed with EO(19)-PO(43)-EO(19) as was the case in previous studies using EO(17)-PO(14)-C(12). This shows the generality of use of aging time to synthesize nanoporous silica films with nonionic surfactants. Finally, a list of "tips and tricks" is provided to facilitate easy reproducible synthesis of double-gyroid nanoporous silica thin films in other laboratories.

The nanostructure of silica and hybrid thin film mesophases templated by phospholipids via an evaporation-induced self-assembly (EISA) process was investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Diacyl phosphatidylcholines with two tails of 6 or 8 carbons were found to template 2D hexagonal mesophases, with the removal of lipid from these lipid/silica films by thermal or UV/O3 processing resulting in a complete collapse of the pore volume. Monoacyl phosphatidylcholines with single tails of 10–14 carbons formed 3D micellular mesophases; the lipid was found to be extractable from these 3D materials, yielding a porous material. In contrast to pure lipid/silica thin film mesophases, films formed from the hybrid bridged silsesquioxane precursor bis(triethoxysilyl)ethane exhibited greater stability toward (both diacyl and monoacyl) lipid removal. Ellipsometric, FTIR, and NMR studies show that the presence of phospholipid suppresses siloxane network formation, while actually promoting condensation reactions in the hybrid material. 1D X-ray scattering and FTIR data were found to be consistent with strong interactions between lipid headgroups and the silica framework.

Controlled assembly of collagen molecules in vitro remains a major challenge for fabricating the next generation of engineered tissues. Here we present a novel electrochemical alignment technique to control the assembly of type-I collagen molecules into highly oriented and densely packed elongated bundles at the macroscale. The process involves application of electric currents to collagen solutions which in turn generate a pH gradient. Through an isoelectric focusing process, the molecules migrate and congregate within a plane. It was possible to fabricate collagen bundles with 50–400 μm diameter and several inches length via this process. The current study assessed the orientational order, and the presence of fibrillar assembly in such electrochemically oriented constructs by polarized optical microscopy, small angle X-ray scattering, second harmonic generation, and electron microscopy. The mechanical strength of the aligned crosslinked collagen bundles was 30-fold greater than its randomly oriented-crosslinked counterpart. Aligned crosslinked collagen bundles had about half the strength of the native tendon. Tendon-derived fibroblast cells were able to migrate and populate multiple macroscopic bundles at a rate of 0.5 mm/day. The anisotropic order within biocompatible collagenous constructs was conferred upon the nuclear morphology of cells as well. These results indicate that the electrochemically oriented collagen scaffolds carry baseline characteristics to be considered for tendon/ligament repair.

A fast, flexible 2D GISAXS simulation method based on the distorted-wave Born approximation (DWBA) has been developed for nanostructured thin films using discrete Fourier transforms of a N × N × N matrix that represents the electron density. By expressing the electron density in matrix form, various models of electron density distributions can be easily simulated and compared to experimental data. In addition to modeling the effects of overall symmetry and orientation on the relative intensities of the Bragg peaks, this approach can be used to evaluate specific details of the nanostructure such as pore connectivity, domain size, domain shape, positional disorder, orientation disorder, and polydispersity. These effects are included in a natural way without making a decoupling approximation between structure factor and form factor. The range of reciprocal space simulated is set by the size of the matrix N and the scale factor β that sets the real-space length of each matrix element, given by 1/(2Nβ) < |s

The double-gyroid phase of nanoporous silica films has been shown to possess facile mass-transport properties and may be used as a mold to fabricate a variety of highly ordered inverse double-gyroid metal and semiconductor films. This phase exists only over a very small region of the binary phase diagram for most surfactants, and it has been very difficult to synthesize metal oxide films with this structure by evaporation-induced self-assembly (EISA). Here, we show the interplay of the key parameters needed to synthesize these structures reproducibly and show that the interfacial curvature may be systematically controlled. Grazing angle of incidence small-angle X-ray scattering (GISAXS) is used to determine the structure and orientation of nanostructured silica films formed by EISA from dilute silica/(poly(ethylene oxide)-b-poly(propylene oxide)-b-alkyl) surfactant solutions. Four different highly ordered film structures are observed by changing only the concentration of the surfactant, the relative humidity during dip-coating, and the aging time of the solution prior to coating. The highly ordered films progress from rhombohedral (Rm) to 2D rectangular (c2m) to double-gyroid (distorted Iad) to lamellar systematically as interfacial curvature decreases. Under all experimental conditions investigated, increasing the aging time of the coating solution was found to decrease the interfacial curvature. In particular, this parameter was critical to being able to synthesize highly ordered, pure-phase double-gyroid films. The key role of the aging time is shown via processing diagrams that map out the interplay between the aging time, composition, and relative humidity. 29Si nuclear magnetic resonance (NMR) spectroscopy and solution-phase small-angle X-ray scattering (SAXS) of the aged coating solutions presented in part I of this series are then used to interpret the effects of aging prior to dip-coating. Specifically, it was found that a predictive model based on volume fractions and the silica cluster stoichiometry obtained from 29Si NMR qualitatively explains the trends observed with composition and aging. However, apart from the effects of relative humidity, a quantitative comparison of the predicted phase with the experimental processing diagram suggests that less-condensed silica clusters are more effective at swelling the EO blocks at early aging times. This enhanced swelling decreases with aging time and results in lower-curvature nanostructures such as the double-gyroid. The decrease in swelling is attributed to the decreased thermodynamic driving force for the more-condensed silica clusters to mix with the EO block of the surfactant.

Nanoporous silica films with the double-gyroid structure offer tremendous technological potential for sensors and separations because of their high surface area and potentially facile transport properties. Further, metals and semiconductors with similar structure open up new opportunities for high-surface-area electrodes, photoelectrochemical devices, photovoltaics, and thermoelectrics. Here, we report a new robust synthesis of highly ordered nanoporous silica films with the double-gyroid structure by evaporation-induced self-assembly (EISA) at room temperature and laboratory humidity using a commercially available EO17−PO12−C14 surfactant. The continuous nanoporous films are synthesized on conducting electrodes. Electrochemical impedance spectroscopy is then used to quantitatively measure the accessible surface area of the underlying electrode via transport through the pore system. It is found that the double-gyroid-structure silica films expose a much higher fraction of the electrode than other commonly...

Highly ordered mesoporous silica thin films have been prepared on silicon substrates by contacting PEO106−PPO70−PEO106 (Pluronic F127) triblock copolymer films with hydrolyzed tetraethyl orthosilic...

Nanoporous silica films have been synthesized by self-assembly on substrates by dip-coating from a combined solution of aged silica oligomers and poly(ethylene oxide)20−poly(propylene oxide)70−poly(ethylene oxides)20 triblock copolymer (Pluronic P123) in ethanol and water. The films are indexed with the rhombohedral space group R3m and are oriented through the thickness of the film with the (111) axis perpendicular to the substrate. Sixfold symmetry perpendicular to the substrate is directly observed by high-resolution top-view field emission scanning electron microscopy over the entire substrate. The films have domains that sample many orientations in the plane of the substrate resulting in a reciprocal space composed of rings. These rings are directly observed by collecting small-angle X-ray scattering data at many angles of incidence from transmission (beam perpendicular to the substrate) all the way down to the grazing angle of incidence. At each rotation, the Bragg spot location in the two-dimension...

Understanding fundamental properties of photoresists and how interactions between photoresist components affect performance targets are crucial to the continued success of photoresists. More specifically, polymer solubility is critical to the overall performance capability of the photoresist formulation. While several theories describe polymer solvent solubility, the most common industrially applied method is Hansen’s solubility parameters. Hansen’s method, based on regular solution theory, describes a solute’s ability to dissolve in a solvent or solvent blend using four physical properties determined experimentally through regression of solubility data in many known solvents. The four physical parameters are dispersion, polarity, hydrogen bonding, and radius of interaction. Using these parameters a relative cohesive energy difference (RED), which describes a polymer’s likelihood to dissolve in a given solvent blend, may be calculated. Leveraging a high throughput workflow to prepare and analyze the thousands of samples necessary to calculate the Hansen’s solubility parameters from many different methacrylate-based polymers, we compare the physical descriptors to reveal a large range of polarities and hydrogen bonding. Further, we find that Hansen’s model correctly predicts the soluble/insoluble state of 3-component solvent blends where the dispersion, polar, hydrogen-bonding, and radius of interaction values were determined through regression of experimental values. These modeling capabilities have allowed for optimization of the photoresist solubility from initial blending through application providing valuable insights into the nature of photoresist.

The Porcupine Seabight Basin is an intra-cratonic rift basin which evolved through recurrent episodes of lithospheric stretching. Structure-contour and isopach maps presented here have been constructed following the interpretation of approx. 10 000 km of seismic data. Together with all the available well data, this integrated database has allowed the tectono-stratigraphic history of the basin to be traced in detail from its earliest inception. The basin was initially formed during the Carboniferous when up to 3.7 km of Autuno-Carboniferous sediments were deposited on a Caledonian and Hercynian structured basement. Late Permian and early Mesozoic sediments at least 1 km thick are preserved in contiguous grabens, and their presence is also inferred within localized sub-basins. Late Liassic crustal doming heralded the onset of the final rifting episode and in the north promoted severe erosion and a rapid discharge of clastic sediments. Rapid subsidence, block faulting and magmatism accompanied the deposition of up to 3.5 km of Middle-Upper Jurassic sediments in asymmetrical sub-basins. The transition from stretching to passive subsidence across the Jurassic-Cretaceous boundary, in combination with localized inversion, abrupt eustatic and environmental changes, generated a basin-wide unconformity. The rift-drift transition in the adjacent proto-Atlantic rift system is recorded in the Porcupine Seabight Basin by voluminous volcanism and a late Lower Cretaceous unconformity. Cretaceous sediments are strongly transgressive and up to 6 km thick. These were superseded during the early Palaeogene by several regressive-transgressive cycles, before the arrival of an upper slope fauna in the mid-Middle Eocene. Cenozoic sediments are up to 4 km thick and record the interplay between (1) the location of the basin Pn the Pyrenean/Alpine foreland, superimposed on the periphery of the Icelandic plume and (2) its development as a marginal Atlantic shelf region. The former is thought to be responsible for Eo-Oligocene faulting, subsidence and igneous activity in the north-east part of the basin and the latter for unconformities and a change in the style of sedimentation, principally due to oceanic circulation changes.

Ordered mesoporous silica thin films were prepared using non-ionic alkyl poly(oxyethylene) surfactants (Brij56: C18EO10) by a vapor phase method. First, a Brij56/H2SO4 composite was deposited on a silicon substrate by spin-coating. The Brij56 film was treated with a tetraethoxysilane (TEOS) and hydrochloric acid (HCl) vapors in a closed vessel. The TEOS and HCl vapors were infiltrated into the film, resulted in a formation of the silica network. Results of a grazing angle of incidence small angle X-ray scattering (GISAXS) show that the films have an ordered structure with an Fmmm symmetry. From an Field emission scanning electron microscope (FESEM) observations, the film has a 3D pore structure.

Preparation of ordered mesoporous carbon films without the use of an intermediate inorganic silica template was achieved from organic-organic assembly of thermally-decomposable triblock copolymer and thermosetting phenolic resin precursors. The films were formed by spin-coating followed by an evaporation-induced self-assembly. Afterwards, decompositon of the organic template and solidification of the carbon precursors are simultaneously performed through a direct carbonization process. Adjusted condition in the ratio of phenolic resin precursors and triblock copolymer allows one to tailor the final mesostructure which include 2D hexagonal phase (c2mm) and 3D face-centered orthorhombic symmetry (Fmmm). These film periodicity uniaxially-contracted normal to the film surface.

A late Permian, Triassic and early Lias rift succession up to 1 km thick is revealed from offshore NW Ireland. Sediments are preserved in deep, narrow grabens from the Donegal Basin in the north, southwestwards through the Erris and Slyne Troughs, to a series of newly defined basins collectively forming the North Porcupine Basin, with a further structure, the ‘Galway Graben’ on the Porcupine Bank. This line of basins, superimposed on a Caledonoid fractured basement, underwent a complex structural evolution, but since the late Permian they developed primarily as a wrench-modified rift system. During the latest Lias, crustal doming west of Britain may have produced a regional angular unconformity and created a source for thick Middle Jurassic alluvial clastics deposited in the Main Porcupine Basin to the south. Early Tertiary transpression of the North Porcupine area caused late-stage fragmentation of the basin. The rift succession consists of continental red beds bounded by two dateable transgressive intervals. These intervals provide valuable stratigraphic control for constraining the timing and scale of seaways propagating across the fracturing Pangean supercontinent, from the late Permian to the early Jurassic. Evidence is also presented for an episode of syn-rift volcanism temporally unique to western Britain and Ireland.

The Porcupine Seabight Basin is a north-south trending, extensional sedimentary basin situated on the continental shelf west of Ireland. It is filled with sedimentary rocks which range in age from Devonian to present-day. A large amount of geological and geophysical data is now available for this basin, mainly as a result of oil industry exploration. In this paper, information from 23 well logs and from regional seismic reflection surveys is used to determine the lithospheric stretching history of the basin. Subsidence analyses indicate that there was one main phase of stretching which began in late Liassic times (∼ 180 Ma), ending in earliest Cretaceous (∼ 145 Ma). Stretching factors at the northern end of the basin are relatively small (β = 1.1–1.7) but increase rapidly southwards along the axis of the Main Porcupine Basin. In the southern part of the region (the Seabight Basin), β is greater than 6. The simplest way to accommodate this rapid variation in stretching is by clockwise rotation of the Porcupine Ridge through approximately 20°, away from the Irish Shelf. Subsidence-derived stretching values are in reasonable agreement with those determined previously from crustal thicknesses based on gravity models and deep seismic data (normal incidence and wide-angle). The existence, location, and inferred age of the Porcupine Median Volcanic Ridge are also consistent with the subsidence-derived stretching factors. After intermittent Paleocene igneous activity, an anomalous increase in the rate of subsidence occurred in the Eocene, between 55 and 42 Ma. There is little evidence that this rapid increase is caused by lithospheric stretching, and we conclude that it must be associated in some unknown way with melt generated by development of the Iceland hotspot.