RESUMEN

A self-aligned double patterning approach using a dopamine chemistry-inspired coating technique has been developed for the fabrication of sub-20 nm patterns. Poly(methyl methacrylate) (PMMA) films were patterned by nanoimprint lithography to form relief features. A thin layer of polydopamine (PDA) was conformally deposited on the surface of the PMMA pattern sidewalls to form a spacer layer. After etching the surface of the PDA layer from the horizontal surfaces and subsequently removing the PMMA template, free-standing PDA sidewall patterns remained that essentially doubled the original PMMA pattern density with decreased feature dimensions as compared to the initial PMMA template structures. The critical dimension of the PDA patterns can be tuned to ∼20 nm by controlling the PDA deposition conditions and further reduced to ∼13 nm by thermal carbonization of the PDA. Both simple lines and more complex rhombic ring features were fabricated by this technique to demonstrate its capacity for replicating arbitrary patterns. This work represents a simple and scalable strategy for preparing well-defined nanostructures with feature sizes usually only accessible via complex leading edge lithographic methods.

RESUMEN

We demonstrate the generation of block copolymer (BCP) line patterns oriented orthogonal to a very small (minimal) topographic trench pattern over arbitrarily large areas using solvent-vapor annealing. Increasing the thickness of BCP films induced an orthogonal alignment of the BCP cylindrical microdomains, where full orthogonal alignment of the cylindrical microdomains with respect to the trench direction was obtained at a film thickness corresponding to 1.70 L0. A capillary flow of the solvent across the trenches was a critical factor in the alignment of the cylindrical microdomains. Grazing incidence small-angle X-ray scattering was used to determine the orientation function of the microdomains, with a value of 0.997 being found reflecting a nearly perfect orientation. This approach to produce orthogonally aligned BCP line patterns could be extended to the nanomanufacturing and fabrication of hierarchical nanostructures.

RESUMEN

A simple and robust method has been developed for the generation of macroscopically ordered hexagonal arrays from the directed self-assembly (DSA) of cylinder-forming block copolymers (BCPs) based on minimal trench patterns with solvent vapor annealing. The use of minimal trench patterns allows us to probe the guided hexagonal arrays of cylindrical microdomains using grazing incidence small angle X-ray scattering (GISAXS), where the sample stage is rotated on the basis of the six-fold symmetry of a hexagonal system. It is found that the (10) planes of hexagonal arrays of cylindrical microdomains are oriented parallel to the underlying trench direction over macroscopic length scales (∼1 × 1 cm2). However, there are misorientations of the hexagonal arrays with short-range ordering. GISAXS patterns show that the hexagonal arrays on the minimal trench pattern are distorted, deviating from a perfect hexagonal lattice. This distortion has been attributed to the absence of topographic constraints in the unconfined direction on the 1-D minimal trench pattern. Also, the frustration of BCP microdomains, arising from the incommensurability between the trench pitch and natural period of the BCP at the base of the trench, influences the distortion of the hexagonal arrays.

RESUMEN

Hydration is central to mitigating surface fouling by oil and microorganisms. Immobilization of hydrophilic polymers on surfaces promotes retention of water and a reduction of direct interactions with potential foulants. While conventional surface modification techniques are surface-specific, mussel-inspired adhesives based on dopamine effectively coat many types of surfaces and thus hold potential as a universal solution to surface modification. Here, we describe a facile, one-step surface modification strategy that affords hydrophilic, and underwater superoleophobic, coatings by the simultaneous deposition of polydopamine (PDA) with poly(methacryloyloxyethyl phosphorylcholine) (polyMPC). The resultant composite coating features enhanced hydrophilicity (i.e., water contact angle of ~10° in air) and antifouling performance relative to PDA coatings. PolyMPC affords control over coating thickness and surface roughness, and results in a nearly 10 fold reduction in Escherichia coli adhesion relative to unmodified glass. The substrate-independent nature of PDA coatings further promotes facile surface modification without tedious surface pretreatment, and offers a robust template for codepositing polyMPC to enhance biocompatibility, hydrophilicity and fouling resistance.

RESUMEN

The fabrication and advanced function of large area biomimetic superhydrophobic surfaces (SHS) and slippery lubricant-infused porous surfaces (SLIPS) are reported. The use of roll-to-roll nanoimprinting techniques enabled the continuous fabrication of SHS and SLIPS based on hierarchically wrinkled surfaces. Perfluoropolyether hybrid molds were used as flexible molds for roll-to-roll imprinting into a newly designed thiol-ene based photopolymer resin coated on flexible polyethylene terephthalate films. The patterned surfaces exhibit feasible superhydrophobicity with a water contact angle around 160° without any further surface modification. The SHS can be easily converted into SLIPS by roll-to-roll coating of a fluorinated lubricant, and these surfaces have outstanding repellence to a variety of liquids. Furthermore, both SHS and SLIPS display antibiofouling properties when challenged with Escherichia coli K12 MG1655. The current article describes the transformation of artificial biomimetic structures from small, lab-scale coupons to low-cost, large area platforms.

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RESUMEN

A pragmatic method to deposit silver nanoparticles on polydopamine-coated nanoimprinted pillars for use as surface-enhanced Raman scattering (SERS) substrates was developed. Pillar arrays consisting of poly(methyl methacrylate) (PMMA) that ranged in diameter from 300 to 500 nm were fabricated using nanoimprint lithography. The arrays had periodicities from 0.6 to 4.0 µm. A polydopamine layer was coated on the pillars in order to facilitate the reduction of silver ions to create silver nucleation sites during the electroless deposition of sliver nanoparticles. The size and density of silver nanoparticles were controlled by adjusting the growth time for the optimization of the SERS performance. The size of the surface-adhered nanoparticles ranged between 75 and 175 nm, and the average particle density was ∼30 particles per µm(2). These functionalized arrays had a high sensitivity and excellent signal reproducibility for the SERS-based detection of 4-methoxybenzoic acid. The substrates were also able to allow the SERS-based differentiation of three types of bacteriophages (λ, T3, and T7).

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RESUMEN

This work reports the creation of superhydrophobic wrinkled surfaces with hierarchical structures at both the nanoscale and microscale. A nanoscale structure with 500 nm line gratings was first fabricated on poly(hydroxyethyl methacrylate) films by nanoimprint lithography while a secondary micro-scale structure was created by spontaneous wrinkling. Compared with random wrinkles whose patterns show no specific orientation, the hierarchical wrinkles exhibit interesting orientation due to confinement effects of pre-imprinted line patterns. The hierarchically wrinkled surfaces have significantly higher water contact angles than random wrinkled surfaces, exhibiting superhydrophobicity with water contact angles higher than 160° and water sliding angle lower than 5°. The hierarchically structured wrinkled surfaces exhibit tunable wettability from hydrophobic to superhydrophobic and there is an observed transition from anisotropic to isotropic wetting behavior achievable by adjusting the initial film thickness.

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RESUMEN

A method for simultaneously patterning and functionalizing thin poly(2-hydroxyethyl methacrylate) films through a reactive silane infusion based wrinkling is developed. Wrinkled patterns with tunable wavelengths on submicrometer size are easily produced over large area surfaces and can express a wide variety of chemical functional groups on the surface. The characteristic wavelength of wrinkling scales linearly with initial film thickness, in agreement with a gradationally swollen film model. Results from X-ray photoelectron spectroscopy confirm that the wrinkled film is composed of two layers: a gradient cross-linked top layer and a uniform un-cross-linked bottom layer. The surface chemical properties of wrinkles can be easily tuned by infusion of different functional silanes. Hierarchical wrinkled patterns with micro/nano structure can be achieved by combining wrinkling with other simple lithography methods. Wrinkled nanopatterns can be used as a mold to transfer the topology to a variety of other materials using nanoimprint lithography.