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ABSTRACT This work explores coatings with thermally switchable wetting behavior, based on block copolymers that possess both hydrophilic and hydrophobic segments. The amphiphilic block copolymers were synthesized by coupling allyl-ended poly(ethylene oxide) (PEO) and hydride-ended poly(dimethylsiloxane) (PDMS) oligomers via a Pt catalyst. One near-symmetric diblock possessed an order-disorder transition temperature ( TODT) of 64 °C. When cooled through TODT in ambient air, the PDMS domains wet the film's surface, producing a hydrophobic coating with a water contact angle (CA) = 90°. However, when cooled in humidified air, hydrophilic PEO domains form at the surface, yielding CA = 30-40°. The coatings can be reversibly switched between the two states by reheating above TODT, in the appropriate environment, and then cooling, rapidly generating the desired room-temperature surface wettability. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 135-140 [ABSTRACT FROM AUTHOR]

Thin films of cylinder-forming polystyrene–poly(n-hexyl methacrylate) diblock copolymers, PS–PHMA,are attractive as nanolithographic templates, an application whichdemands good control over the thin-film structureyet the qualityof order achieved to date in PS–PHMA films has fallen shortof this ideal. In the present work, a series of PS–PHMA diblocksof varying composition, all forming PS cylinders, are synthesizedand their morphology studied as a function of film thickness in bothnonsheared and shear-aligned films. In nonsheared films, the cylinderaxis orientation relative to the surface switches from parallel toperpendicular as a function of film thickness; this oscillation isdamped out as the fraction of the cylinder-forming block (PS) increases,away from the sphere–cylinder phase boundary. In aligned films,thicknesses which possess the highest coverage of parallel cylindersprior to shear show the highest quality of alignment postshear, asmeasured by the in-plane orientational order parameter of the cylinderaxis. In well-aligned samples of optimal thickness, the quality ofalignment is limited by isolated dislocations, whose density is highestat high PS contents, and by undulations in the cylinders’ trajectories,whose impact is most severe at low PS contents; consequently, polymerswhose compositions lie in the middle of the cylinder-forming regionexhibit the highest quality of alignment. [ABSTRACT FROM AUTHOR]

Flowcoating is a popular techniquefor generating thin (5–200nm), substrate-supported polymer films. In this process, a reservoirof coating fluid is held between the horizontal substrate and a nearlyhorizontal blade above the substrate; a film of fluid is drawn outof the reservoir by moving the substrate. Accelerating the substrateproduces a film with a thickness gradient, particularly useful forhigh-throughput measurements where film thickness is an importantparameter. The present work compares experimental film thickness profileswith a model based on a Landau–Levich treatment to identifythe experimental parameters which govern film thickness. The key parametersare the capillary number and the radius of curvature of the reservoir’sstatic meniscus, which is set by the blade angle, gap height, solutionreservoir volume, and contact angles of the fluid with the blade andsubstrate. The results show excellent quantitative agreement withthe first-principles model; the model thus provides a design approachwhich allows a user to produce polymer thin films of virtually anydesired thickness profile. [ABSTRACT FROM AUTHOR]