Mapping the transition to superwetting state for nanotextured surfaces templated from block-copolymer self-assembly.

Adding roughness to hydrophilic surfaces is generally expected to enhance their wetting by water. Indeed, global free energy minimization predicts decreasing contact angles when roughness factor or surface energy increases. However, experimentally it is often found that water spreading on rough surfaces is impeded by pinning effects originating from local free energy minima; an effect, largely neglected in scientific literature.

Directed self-assembly of a high-chi block copolymer for the fabrication of optical nanoresonators.

In this paper, we report on the fabrication of optical nanoresonators using block copolymer lithography. The nanostructured gratings or nanofins were fabricated using a silicon-containing block copolymer on a chromium coated silicon-on-insulator substrate. The etch resistance of the block copolymer template enables a unique patterning technique for high-aspect-ratio silicon nanofins.

High molecular weight block copolymer lithography for nanofabrication of hard mask and photonic nanostructures.

An unusual dot pattern was realized via self-assembly of high molecular weight polystyrene-block-polydimethylsiloxane (PS-b-PDMS) copolymer by a simple one-step solvent annealing process, optimized based on Hansen solubility parameters. Annealing PS-b-PDMS under neutral solvent vapors at room temperature produces an ordered arrangement of dots with ∼112 nm spacing and ∼54 nm diameter. The template is highly resistant to dry etching with chlorine-based plasma, enabling its utilization on a variety of hard masks and substrates.

Experimental demonstration of graphene plasmons working close to the near-infrared window.

Due to strong mode confinement, long propagation distance, and unique tunability, graphene plasmons have been widely explored in the mid-infrared and terahertz windows. However, it remains a big challenge to push graphene plasmons to shorter wavelengths to integrate graphene plasmon concepts with existing mature technologies in the near-infrared region. We investigate localized graphene plasmons supported by graphene nanodisks and experimentally demonstrate graphene plasmon working at 2 μm with the aid of a fully scalable block copolymer self-assembly method.

Wafer-Scale Nanopillars Derived from Block Copolymer Lithography for Surface-Enhanced Raman Spectroscopy.

We report a novel nanofabrication process via block copolymer lithography using solvent vapor annealing. The nanolithography process is facile and scalable, enabling fabrication of highly ordered periodic patterns over entire wafers as substrates for surface-enhanced Raman spectroscopy (SERS). Direct silicon etching with high aspect ratio templated by the block copolymer mask is realized without any intermediate layer or external precursors.

Photocatalytic Nanostructuring of Graphene Guided by Block Copolymer Self-Assembly.

Nanostructured graphene exhibits many intriguing properties. For example, precisely controlled graphene nanomeshes can be applied in electronic, photonic, or sensing devices. However, fabrication of nanopatterned graphene with periodic supperlattice remains a challenge.

Substrate tolerant direct block copolymer nanolithography.

Block copolymer (BC) self-assembly constitutes a powerful platform for nanolithography. However, there is a need for a general approach to BC lithography that critically considers all the steps from substrate preparation to the final pattern transfer. We present a procedure that significantly simplifies the main stream BC lithography process, showing a broad substrate tolerance and allowing for efficient pattern transfer over wafer scale.

Transfer of Direct and Moiré Patterns by Reactive Ion Etching Through Ex Situ Fabricated Nanoporous Polymer Masks.

We present a conceptually simple approach to nanolithographic patterning utilizing ex situ fabricated nanoporous masks from block copolymers. The fabricated block copolymer (BC) masks show predictable morphology based on the correlation between BC composition and bulk properties, independent of substrates' surface properties. The masks are prepared by microtoming of prealigned nanoporous polymer monoliths of hexagonal morphology at controlled angles; they appear as 30-60 nm thick films of typical dimensions 100 μm × 200 μm.

Sodium Dodecyl Sulfate (SDS)-Loaded Nanoporous Polymer as Anti-Biofilm Surface Coating Material.

Biofilms cause extensive damage to industrial settings. Thus, it is important to improve the existing techniques and develop new strategies to prevent bacterial biofilm formation. In the present study, we have prepared nanoporous polymer films from a self-assembled 1,2-polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS) block copolymer via chemical cross-linking of the 1,2-PB block followed by quantitative removal of the PDMS block.

Nanoporous materials modified with biodegradable polymers as models for drug delivery applications.

Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model.

Gyroid nanoporous membranes with tunable permeability.

Understanding the relevant permeability properties of ultrafiltration membranes is facilitated by using materials and procedures that allow a high degree of control on morphology and chemical composition. Here we present the first study on diffusion permeability through gyroid nanoporous cross-linked 1,2-polybutadiene (1,2-PB) membranes with uniform pores that, if needed, can be rendered hydrophilic. The gyroid porosity has the advantage of isotropic percolation with no need for structure prealignment.

Patterned hydrophilization of nanoporous 1,2-PB by thiol-ene photochemistry.

We present an efficient method for functionalizing the large polymer-air interface of a gyroid nanoporous polymer. The hydrophilicity of nanoporous cross-linked 1,2-polybutadiene is tuned by thiol-ene photo-grafting of mercaptosuccinic acid or sodium 2-mercaptoethanesulfonate. The reaction is monitored by FT-IR, UV-Vis, contact angle, and gravimetry.

Physisorption of SDS in a hydrocarbon nanoporous polymer.

Surface modification of nanoporous 1,2-polybutadiene of pore diameter approximately 15 nm was accomplished by physisorption of sodium dodecyl sulfate (SDS) in water. Loading of the aqueous solution and the accompanying physisorption of SDS into the hydrophobic nanoporous films were investigated in a wide range of concentrations. The loading showed varying dependence on the SDS concentration.

UV patterned nanoporous solid-liquid core waveguides.

Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (deltan = 0.20) is a result of selective water infiltration.

Surface modification of nanoporous 1,2-polybutadiene by atom transfer radical polymerization or click chemistry.

Surface-initiated atom transfer radical polymerization (ATRP) and click chemistry were used to obtain functional nanoporous polymers based on nanoporous 1,2-polybutadiene (PB) with gyroid morphology. The ATRP monolith initiator was prepared by immobilizing bromoester initiators onto the pore walls through two different methodologies: (1) three-step chemical conversion of double bonds of PB into bromoisobutyrate, and (2) photochemical functionalization of PB with bromoisobutyrate groups. Azide functional groups were attached onto the pore walls before click reaction with alkynated MPEG.

Protein aggregation and degradation during iodine labeling and its consequences for protein adsorption to biomaterials.

Protein adsorption on modified and unmodified polymer surfaces investigated through radiolabeling experiments showed a tendency for higher than expected albumin and immunoglobulin G (IgG) adsorption. Possible enhanced protein aggregation and degradation caused by the iodine labeling method used were analyzed through chromatography and spectroscopy techniques. Results show that the iodine labeling method using chloramine-T (CAT) as an oxidizing agent can cause both enhanced aggregation and fragmentation of proteins.

Nanoporous materials with spherical and gyroid cavities created by quantitative etching of polydimethylsiloxane in polystyrene-polydimethylsiloxane block copolymers.

A new method for quantitative etching of the poly(dimethylsiloxane) block in polystyrene-poly(dimethylsiloxane) (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride renders a nanoporous material (NPM) with the remaining glassy PS maintaining the original bulk morphology. 1H NMR, mass difference, size exclusion chromatography, and X-ray photoelectron spectroscopy were used to characterize the materials before and after etching.