Nanoscale self-assembly of block copolymer thin films has garnered significant research interest for nanotemplate design and membrane applications. To fulfill these roles, control of thin film morphology and orientation is critical. Solvent vapor annealing (SVA) treatments can be used to kinetically trap morphologies in thin films not achievable by traditional thermal treatments, but many variables affect the outcome of SVA, including solvent choice, total solvent concentration/swollen film thickness, and solvent removal rate. In this work, we systematically examined the effect of solvent removal rate on the final thin film morphology of a cylinder-forming ABA triblock copolymer. By kinetically trapping the film morphologies at key points during the solvent removal process and then using successive ultraviolet ozone (UVO) etching steps followed by atomic force microscopy (AFM) imaging to examine the through-film morphologies of the films, we determined that the mechanism for cylinder reorientation from substrate-parallel to substrate-perpendicular involved the propagation of changes at the free surface through the film toward the substrate as a front. The degree of reorientation increased with successively slower solvent removal rates. Furthermore, the AFM/UVO etching scheme permitted facile real-space analysis of the thin film internal structure in comparison to cross-sectional transmission electron microscopy.

Solvent vapor annealing (SVA) with solvent mixtures is a promising approach for controlling block copolymer thin film self-assembly. In this work, we present the design and fabrication of a solvent-resistant microfluidic mixing device to produce discrete SVA gradients in solvent composition and/or total solvent concentration. Using this device, we identified solvent composition dependent morphology transformations in poly(styrene-b-isoprene-b-styrene) films. This device enables faster and more robust exploration of SVA parameter space, providing insight into self-assembly phenomena.

We present a spatially resolved approach for the solvent vapor annealing (SVA) of block copolymer thin films that permits the facile and relatively rapid manipulation of nanoscale ordering and nanostructure orientation. In our method, a localized (point) SVA zone is created through the use of a vapor delivery nozzle. This point annealing zone can be rastered across the thin film using a motorized stage to control the local nanoscale structure and orientation in a cylinder-forming ABA triblock copolymer thin film. At moderate rastering speeds (∼100 μm/s) (i.e., relatively modest annealing time at a given point), the film displayed ordered cylindrical nanostructures with the cylinders oriented parallel to the substrate surface. As the rastering speed was decreased (∼10 μm/s), the morphology transformed into a surface nanostructure indicative of cylinders oriented perpendicular to the substrate surface. These perpendicular cylinder orientations also were created by rastering multiple times over the same region, and this effect was found when rastering in either retrace (overlapping) or crossed-path (orthogonal) geometries. Similar trends in nanostructure orientation and ordering were obtained from various nozzle diameters by accounting for differences in solvent flux and annealing time, illustrating the universality of this approach. Finally, we note that our "stylus-based" raster solvent vapor annealing technique allows a given point to be solvent annealed approximately 2 orders of magnitude faster than conventional "bell jar" solvent vapor annealing.

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3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are effective agents in lowering cholesterol and triglycerides and are being used by human immunodeficiency virus-positive patients to treat the lipid elevation that may be associated with antiretroviral therapy. Many HMG-CoA reductase inhibitors and protease inhibitors are metabolized by the same cytochrome P450 enzyme 3A4 (CYP3A4). In addition, many protease inhibitors are potent inhibitors of CYP3A4. Therefore, coadministration of these two classes of drugs may cause significant drug interactions. This open-label, multiple-dose study was performed to determine the interactions between nelfinavir, a protease inhibitor, and two HMG-CoA reductase inhibitors, atorvastatin and simvastatin, in healthy volunteers. Thirty-two healthy subjects received either atorvastatin calcium (10 mg once a day) or simvastatin (20 mg once a day) for the first 14 days of the study. Nelfinavir (1,250 mg twice a day) was added on days 15 to 28. Pharmacokinetic assessment was performed on days 14 and 28. The study drugs were well tolerated. Nelfinavir increased the steady-state area under the plasma concentration-time curve during one dosing period (AUC ) of atorvastatin 74% and the maximum concentration (C max ) of atorvastatin 122% and increased the AUC of simvastatin 505% and the C max of simvastatin 517%. Neither atorvastatin nor simvastatin appeared to alter the pharmacokinetics of nelfinavir. It is recommended that coadministration of simvastatin with nelfinavir should be avoided, whereas atorvastatin should be used with nelfinavir with caution.