Step edges in thin films of lamellar-forming diblock copolymer

Self-consistent field theory (SCFT) is used to study the step edges that occur in thin films of lamellar-forming diblock copolymer, when the surfaces each have an affinity for one of the polymer components. We examine film morphologies consisting of a stack of ν continuous monolayers and one semi-infinite bilayer, the edge of which creates the step. The line tension of each step morphology is evaluated and phase diagrams are constructed showing the conditions under which the various morphologies are stable. The predicted behavior is then compared to experiment. Interestingly, our atomic force microscopy (AFM) images of terraced films reveal a distinct change in the character of the steps with increasing ν, which is qualitatively consistent with our SCFT phase diagrams. Direct quantitative comparisons are not possible because the SCFT is not yet able to probe the large polymer/air surface tensions characteristic of experiment.

Morphology induced spinodal decomposition at the surface of symmetric diblock copolymer films

Atomic force microscopy is used to study the ordering dynamics of symmetric diblock copolymer films. The films order to form a lamellar structure which results in a frustration when the film thickness is incommensurate with the lamellae. By probing the morphology of incommensurate films in the early ordering stages, we discover an intermediate phase of lamellae arranged perpendicular to the film surface. This morphology is accompanied by a continuous growth in amplitude of the film surface topography with a characteristic wavelength, indicative of a spinodal process. Using selfconsistent field theory, we show that the observation of perpendicular lamellae suggests an intermediate state with parallel lamellae at the substrate and perpendicular lamellae at the free surface. The calculations confirm that the intermediate state is unstable to thickness fluctuations, thereby driving the spinodal growth of surface structures.

Control and analysis of oriented thin films of lipid inverse bicontinuous cubic phases using grazing incidence small-angle X‑ray scattering

Lipid cubic phases are complex nanostructures that form naturally in a variety of biological systems, with applications including drug delivery and nanotemplating. Most X-ray scattering studies on lipid cubic phases have used unoriented polydomain samples as either bulk gels or suspensions of micrometer-sized cubosomes. We present a method of investigating cubic phases in a new form, as supported thin films that can be analyzed using grazing incidence small-angle X-ray scattering (GISAXS). We present GISAXS data on three lipid systems: phytantriol and two grades of monoolein (research and industrial). The use of thin films brings a number of advantages. First, the samples exhibit a high degree of uniaxial orientation about the substrate normal. Second, the new morphology allows precise control of the substrate mesophase geometry and lattice parameter using a controlled temperature and humidity environment, and we demonstrate the controllable formation of oriented diamond and gyroid inverse bicontinuous cubic along with lamellar phases. Finally, the thin film morphology allows the induction of reversible phase transitions between these mesophase structures by changes in humidity on subminute time scales, and we present timeresolved GISAXS data monitoring these transformations.

Hydrogen-bonded complexes and blends of poly(acrylic acid) and methylcellulose: nanoparticles and mucoadhesive films for Ocular Delivery of Riboflavin

Poly(acrylic acid) (PAA) and methylcellulose (MC) are able to form hydrogen-bonded interpolymer complexes (IPCs) in aqueous solutions. In this study, the complexation between PAA andMC is explored in dilute aqueous solutions under acidic conditions. The formation of stable nanoparticles is established,whose size and colloidal stability are greatly dependent on solution pH and polymers ratio in the mixture. Poly(acrylic acid) and methylcellulose are also used to prepare polymeric films by casting from aqueous solutions. It is established that uniform films can be prepared by casting from polymer mixture solutions at pH 3.4–4.5. At lower pHs (pH<3.0) the films have inhomogeneous morphology resulting from strong interpolymer complexation and precipitation of polycomplexes, whereas at higher pHs (pH 8.3) the polymers form fully immiscible blends because of the lack of interpolymer hydrogen-bonding. The PAA/MC films cast at pH 4 are shown to be non-irritant to mucosal surfaces. These films provide a platform for ocular formulation of riboflavin, a drug used for corneal crosslinking in the treatment of keratoconus. An in vitro release of riboflavin as well as an in vivo retention of the films on corneal surfaces can be controlled by adjusting PAA/MC ratio in the formulations.

Predicting the orientation of lipid cubic phase films

Lipid cubic phase films are of increasingly widespread importance, both in the analysis of the cubic phases themselves by techniques including microscopy and X-ray scattering, and in their applications, especially as electrode coatings for electrochemical sensors and for templates for the electrodeposition of nanostructured metal. In this work we demonstrate that the crystallographic orientation adopted by these films is governed by minimization of interfacial energy. This is shown by the agreement between experimental data obtained using grazing-incidence small-angle X-ray scattering (GI-SAXS), and the predicted lowest energy orientation determined using a theoretical approach we have recently developed. GI-SAXS data show a high degree of orientation for films of both the double diamond phase and the gyroid phase, with the [111] and [110] directions respectively perpendicular to the planar substrate. In each case, this matches the lowest energy facet calculated for that particular phase.

Detection of nitroaromatic vapours with diketopyrrolopyrrole thin films: exploring the role of structural order and morphology on thin film properties and fluorescence quenching efficiency

Sensitive optical detection of nitroaromatic vapours with diketo-pyrrolopyrrole thin films is reported for the first time and the impact of thin film crystal structure and morphology on fluorescence quenching behaviour demonstrated.

At the Front: common traitors in West German war films of the 1950s

The article looks at the figure of the traitor in 1950s’ West German films about World War II. It focuses on the representation of Wehrmacht soldiers who entertain relations with the Soviet enemy and are therefore seen to betray their nation. The discussion of three well-known films – 08/15, Der Arzt von Stalingrad, and Unruhige Nacht – shows these ‘traitors’ to have a highly ambivalent function: their narrative punishment is part of German post-war exculpation, yet they are also reminders of German guilt and ethical responsibility towards the ‘other’.

International films and international markets: the globalisation of Hollywood entertainment, c.1921-1951

The international appeal of Hollywood films through the twentieth century has been a subject of interest to economic and film historians alike. This paper employs some of the methods of the economic historian to evaluate key arguments within the film history literature explaining the global success of American films. Through careful analysis of both existing and newly constructed data sets, the paper examines the extent to which Hollywood's foreign earnings were affected by: film production costs; the extent of global distribution networks; and also the international orientation of the films themselves. The paper finds that these factors influenced foreign earnings in quite distinct ways, and that their relative importance changed over time. The evidence presented here suggests a degree of interaction between the production and distribution arms of the major US film companies in their pursuit of foreign markets that would benefit from further archival-based investigation.

Beyond difference: female participation in the Brazilian film revival of the 1990s

In this chapter, I will focus on the female participation in what became known as ‘The Retomada do Cinema Brasileiro’, or the Brazilian Film Revival, by thinking beyond differences of gender, class, age and ethnicity. I will first re-consider the Retomada phenomenon against the backdrop of its historical time, so as to evaluate whether the production boom of the period translated into a creative peak, and, if so, how much of this carried onto the present day. I will then look at the female participation in this phenomenon not just in terms of numerical growth of women film directors, admittedly impressive, but only partially reflective of the drastic changes in the modes of production and address effected by the neoliberal policies introduced in the country in the mid 1990s. I will argue that the most decisive contribution brought about by the rise of women in Brazilian filmmaking has been the spread of team work and shared authorship, as opposed to a mere aspiration to the auteur pantheon, as determined by a notoriously male-oriented tradition. Granted, films focusing on female victimisation were rife during the Retomada period and persist to this day, and they have been, and continue to be, invaluable for the understanding of women’s struggles in the country. However, rather than resorting to feminist readings of representational strategies in these films, I will draw attention to other, presentational aesthetic experiments, open to the documentary contingent and the unpredictable real, which, I argue, suspend the pedagogical character of representational narratives. In order to demonstrate that new theoretical tools are needed to understand the gender powers at play in contemporary world cinema, I will, to conclude, analyse an excerpt of the film, Delicate Crime (Crime delicado, Beto Brant, 2006), where team work comes out as a particularly effective female, and feminist, procedure.