Honeycomb-patterned Thin Films Research Articles

Effect of honeycomb-patterned structure on electrical and magnetic behaviors of poly(ɛ-caprolactone)/capped magnetic nanoparticle composite films

Novel biocompatible poly(ɛ-caprolactone) (PCL) was synthesized via in situ ring-opening polymerization of ɛ-caprolactone under different concentrations (10, 20, and 30 wt%) of capped magnetic nanoparticles (CMPs). The prepared PCL/CMP composites were characterized using Fourier transform infrared, UV-vis spectra, and X-ray photoelectron spectroscopy to demonstrate the interaction between PCL and CMP. X-ray diffraction patterns, scanning electron microscopy with energy dispersive X-ray spectroscopy, and thermogravimetric analysis were used to understand the structural nature and thermal stability of the polymer composites. Honeycomb-patterned thin films were fabricated by casting the composite solutions under humid conditions. The I–V characteristics and magnetic behavior of the honeycomb-patterned films were observed and compared with those of the flat thin composite films. The honeycomb-patterned PCL/CMP composite films revealed higher conductivity than the flat films and showed a hysteresis loop in the magnetization plotted against the applied magnetic field for magnetic behavior.

Fabrication of honeycomb-patterned polyaniline composite films containing cellulose triacetate with high conductivity and mechanical stability

Polyaniline (PANI) biocomposites were prepared via in situ polymerization of aniline monomer with cellulose triacetate (CTA) and by using ammonium persulfate as an initiator in an aqueous solvent. The composites exhibited high solubility in organic solvents due to the incorporated CTA component, and enabled the fabrication of honeycomb-patterned thin films by casting the PANI composite solutions under humid conditions. The honeycomb-patterned PANI–CTA composite films showed a high conductivity corresponding to about 1.5 S/cm, good mechanical stability, and high flexibility. The composites have a potential advantage comparing to pure PANI because of biodegradability and high solubility due to included CTA. These composite films can usefully be applied in the field of bio-nanotechnology and medicine including micro-structured electrode surfaces, filters for cell sorting, and bio-interfaces and so on. POLYM. COMPOS., 37:2649–2656, 2016. © 2015 Society of Plastics Engineers

Fabrication of honeycomb-patterned polyaniline composite films using chemically modified polyaniline nanoparticles

A novel polyaniline composite was prepared by in situ ring-opening polymerization of ε-caprolactone in the presence of chemically modified polyaniline nanoparticles (PANI-NPs) using Sn(Oct)2 as an initiator, which exhibited a high solubility in organic solvent to enable the fabrication of stable honeycomb-patterned thin films by casting the PANI composite solutions under humid conditions. The chemically modified PANI-NPs were produced from the polymerization of aniline in the cationic surfactant of cetyl trimethyl ammonium bromide (CTAB). The polyaniline composites were characterized via Fourier transform infrared, ultraviolet–visible spectroscopy, X-ray diffraction, transmission electron microscopy, and thermogravimetry. The analyses indicated that the PANI-NPs were well incorporated in the poly(ε-caprolactone) (PCL) backbone. The patterned PANI composite films showed high DC conductivity up to 10−2 S/cm, which can be useful in applications such as bio-sensing, bio-nanotechnology, biological science, and medicine.

Fabrication of honeycomb-patterned poly(ε-caprolactone) composite films containing chemically modified silver nanoparticles

Biocompatible composites containing poly(ε-caprolactone) (PCL) were prepared by incorporating different weight percentages of silver (Ag) nanoparticles with the particle size of about 10nm modified by dodecanethiol. The synthesized PCL/Ag composites were characterized by Fourier transform infrared and UV–vis spectroscopy, and the surface morphology of these composites was identified by scanning electron microscopy and transmission electron microscopy. Honeycomb-patterned thin films with the film thickness of 20–30μm was fabricated by casting the composite solution under humid conditions without separation of Ag nanoparticles due to the chemical modification. The dependence of the DC conductivity and pattern structure of the thin films on Ag concentration was studied.

Porphyrin-based honeycomb films and their antibacterial activity.

Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields.

Fabrication and characterization of honeycomb-patterned film from poly(ɛ-caprolactone)/poly((R)-3-hydroxybutyric acid)/reduced graphene oxide composite

A novel biocomposite of poly(ɛ-caprolactone) (PCL) containing poly((R)-3-hydroxybutyric acid) (PHB) and a fixed amount of reduced graphene oxide (RGO) was synthesized. The characterization of the composite by Fourier-transform infrared, ultraviolet–visible spectral analysis, differential scanning calorimetry and thermogravimetric analysis indicates a strong interaction between PCL and PHB/RGO. Honeycomb-patterned thin films with regular structures were fabricated by casting the composite solutions under humid conditions. The temperature-dependent direct current (DC) conductivity of the patterned films was studied over the range of 290–335 K, revealing the semiconducting behavior of the transport properties of the composite films. The presence of the PHB component not only slightly increased the conductivity but also accelerated the biodegradability of the PCL matrix. Biocompatible poly(ɛ-caprolactone) (PCL)/poly((R)-3-hydroxybutyric acid) (PHB)/reduced graphene oxide (RGO) composites with fixed wt% of RGO and different wt% of PHB were prepared using in situ ring-opening polymerization technique of ɛ-caprolactone monomer in the presence of RGO and PHB. The honeycomb-patterned films were fabricated by casting the composite solutions under humid conditions. The films exhibit a semiconducting behavior of the composite materials. The presence of PHB component not only slightly increases the conductivity but also accelerate the biodegradability of the PCL matrix.

Structural characterization and DC conductivity of honeycomb-patterned poly(ε-caprolactone)/gold nanoparticle-reduced graphite oxide composite films

Biocompatible composites containing poly(ε-caprolactone) (PCL) were prepared by incorporating different weight percentages of gold nanoparticles dispersed on reduced graphite oxide (GNP-RGO). The synthesized PCL-GNP-RGO composites were characterized by Fourier transform infrared and UV–vis spectroscopy. Honeycomb-patterned thin films were fabricated by casting the composite solution under humid conditions. The dependence of the room-temperature DC conductivity and pattern structure of the films on the GNP-RGO concentration were studied.

Photo-controlled fabrication of self-organized structures in honeycomb-patterned thin films with light-sensitive amphiphilic copolymer

The structures of honeycomb-patterned thin polymer films fabricated by casting polystyrene solution under humid conditions were controlled by illumination of ultraviolet (UV) light by the assistance of an added light-sensitive amphiphilic copolymer (Als) in the casting solution. Als was synthesized through the radical copolymerization of ruthenium(4-vinyl-4′-methyl-2,2′-bipyridine)bis(2,2′-bipyridine)bis(hexaflurophosphate) with N-vinylcarbazole. The synthesized Als was characterized using spectroscopic methods and a thermogravimetric analyzer. An appropriate duration of light illumination in a suitable concentration of Als minimized the irregularity of the honeycomb pattern. However, irregular patterns were induced by an excessive amount of Als or by excessive illumination time.

Self‐Organized Polymer Nanocomposite Inverse Opal Films with Combined Optical Properties

Inverse opal films with unique optical properties have potential as photonic crystal materials and have stimulated wide interest in recent years. Herein, iridescent hybrid polystyrene/nanoparticle macroporous films have been prepared by using the breath-figure method. The honeycomb-patterned thin films were prepared by casting gold nanoparticle-doped polystyrene solutions in chloroform at high relative humidity. Highly ordered hexagonal arrays of monodisperse pores with an average diameter of 880 nm are obtained. To account for the observed features, a microscopic phase separation of gold nanoparticles is proposed to occur in the breath-figure formation. That is, individual gold nanoparticles adsorb at the solution/water interface and effectively stabilize condensed water droplets on the solution surface in a hexagonal array. Alternatively, at high nanoparticle concentrations the combination of breath-figure formation and nanoparticle phase separation leads to hierarchical structures with spherical aggregates under a honeycomb monolayer. The films show large features in both the visible and NIR regions that are attributed to a combination of nanoparticle and ordered-array absorptions. Organic ligand-stabilized CdSe/CdS quantum dots or Fe(3)O(4) nanoparticles may be loaded into the honeycomb structure to further modify the films. These results demonstrate new methods for the fabrication and functionalization of inverse opal films with potential applications in photonic and microelectronic materials.

Facile Fabrication of Honeycomb-Patterned Thin Films of Amorphous Calcium Carbonate and Mosaic Calcite

Facile fabrication of honeycomb-patterned thin films of amorphous calcium carbonate (ACC) and mosaic calcite was achieved via colloidal lithography at the solution surface. At first, honeycomb-patterned ACC (HP-ACC) thin films were fabricated by a polymer-induced ACC coating of the monolayer colloidal crystal (MCC) template at the air/water interface. Subsequent controlled crystallization of the preformed HP-ACC thin films under different conditions led to honeycomb-patterned, crystalline films with different microstructures. In particular, honeycomb-patterned, mosaic calcite thin films composed of single-crystalline calcite plates could form when thermal treatment at 400 °C was applied to the amorphous films. Additionally, dye molecules were incoporated into the HP-ACC thin film during its formation, enabling further functionality of the patterned thin film with fluorescence. Furthermore, the highly ordered HP-ACC thin films possessed brilliant structural colors and exhibited typical photonic properties.

Self-Organized Honeycomb-Patterned Microporous Polystyrene Thin Films Fabricated by Calix[4]arene Derivatives

Calix[4]arene derivatives bearing carboxyl groups at the upper rim and alkyl groups at the lower rim were synthesized. Micrometer-size porous honeycomb-patterned thin films were prepared by evaporating chloroform solution of polystyrene containing the calixarene derivatives under high humidity. These films were coated on gold electrodes of QCM, and the high-frequency changes were observed to detect volatile organic compounds such as dichlorobenzene.

Honeycomb-patterned thin films of amphiphilic polymers as cell culture substrates

Recently, we have found honeycomb patterns with sub-micron line width that form during the non-equilibrium process of cast film formation. The honeycomb-patterned films were fabricated using four macromolecular compounds (amphiphilic copolymers containing lactose units or carboxyl groups as side-chains and polyion complexes composed of anionic polysaccharides). The specific binding of lactose by lectin confirmed that the lactose moieties contained in the honeycomb films work as biologically active ligands. Bovine serum albumin (BSA) labeled with fluorescein was covalently attached to the honeycomb films using water-soluble carbodiimide (WSC) as an activator. Using fluorescence imaging of the modified film, we could show that the proteins are immobilized on the honeycomb patterns. Adhesion of bovine aorta endothelial cells (ECs) to the honeycomb films indicates that the honeycomb structure works as an adhesive site for the cells.