Honeycomb Patterned Research Articles

PH-sensitive fractal structured polyaniline in the honeycomb-patterned porous polymer film for the detection of dopamine and glucose

Using highly pH-sensitive fractal structured polyaniline (f-PANI) inducing conductivity change in the honeycomb-patterned (HCP) porous polymer film, we have applied for the detection of dopamine and glucose. Fractal-structured PANI in the HCP porous polymer film is formed by the same method recently reported using solid–liquid interfacial reaction. For the interfacial reaction, the HCP polystyrene (PS) porous film containing benzoyl peroxide (BPO) was immersed into the aniline aqueous solution under conditions of non-stirring for the growing of fractal structure instead of aggregated PANI. The pH sensitivity of the conductivity of the HCP film functionalized with fractal structured PANI was so high compared to the HCP film functionalized with simple aggregated PANI (a-PANI) under stirring conditions for the solid–liquid interfacial reaction. By using the high pH sensitive fractal structured PANI functionalized HCP film, dopamine, and glucose were selectively detected. The film acts as a micro reactor for the effective detection of dopamine and glucose.

Effect of Knitting Pattern of PP Mesh on the Flexural Properties of Heat-cured PMMA Denture Base Resin

Heat-cured polymethyl methacrylate is (PMMA) is the most common denture base material and some mechanical properties such as flexural strength and impact resistance etc. may lead to fail, besides its excellent properties. Polypropylene (PP) hernia mesh is a commercially available medical textile used in surgical repair of different types of hernia. It was aimed to investigate the effect of two different knitting patterns of PP meshes on the flexural properties of the PMMA denture base resin when they are used as reinforcement and compare with glass fiber mesh reinforced and no mesh used resins. Knitting patterns of the PP mesh structures were hexagonal honeycomb pattern and square pattern and these were used as single or double layer as reinforcement. 6 groups were established in the study: control group with no mesh and 5 reinforced groups with meshes (glass fiber mesh, single layer honeycomb patterned PP mesh, double layer honeycomb patterned PP mesh, single layer square patterned PP mesh, double layer square patterned PP mesh). A total of 60 samples with the dimensions of 65x10x3 mm, n=10 in each group were fabricated. The flexural strength, maximum deformation, and flexural modulus were determined by three-point bending test. Fracture surfaces were evaluated by scanning electron microscopy. The obtained data were statistically analyzed by two-way ANOVA test with Bonferroni corrections. The single layer square patterned PP mesh group exhibited the highest (76.67 ± 7.64 MPa), and the control group showed the lowest (63.49 ± 7.18 MPa) flexural strength values. The single layer glass fiber mesh group showed the highest (7.13 ± 0.55 mm) and the control group showed the lowest (4.72 ± 0.81 mm) maximum deformation values. The single layer glass fiber mesh group exhibited the highest (2131.87 ± 205.76 MPa), and the control group exhibited the lowest (1582.26 ± 98.63 MPa) flexural modulus values. Significant increase in flexural strength was observed in all polypropylene mesh-reinforced groups compared to the control group except double layer honeycomb patterned PP mesh group (p < 0.05). Using PP fiber mesh for reinforcement provide a very favorable aesthetic view and PP fiber mesh is concluded to be a promising material for reinforcement of heat-cured PMMA denture base resins.

Large-area customizable honeycomb patterned polycarbonate derived from roofing sheet waste for a slippery liquid-infused porous surface

Polycarbonate (PC) is widely recognized for its exceptional ductility, high heat resistance, and impressive transparency, making it a material of great importance and extensive use. However, the increasing accumulation of PC-based solid waste, particularly discarded roofing sheets, has raised significant environmental concerns worldwide. The incineration or incomplete decomposition of polycarbonate waste in landfills generates hazardous by-products such as microplastics and Bisphenol-A (BPA). In this study, we propose an innovative recycling approach that converts low-grade roofing sheets waste into large-area customizable honeycomb-patterned PC, offering great potential for the development of slippery liquid-infused porous surfaces (SLIPs). The achievement of a highly ordered honeycomb pattern array is facilitated through the implementation of an improved phase separation (IPS) method, employing methanol as a pore inducer and template droplet stabilizer, thereby eliminating the necessity for surfactants or specially engineered polymers. This approach enables the formation of a monolayered pattern array with uniform closed dead-end pores shaped like round flowerpots, holding immense promise for creating SLIPs with self-cleaning, anti-fouling and electrification properties due to the reduction in surface-contaminant adhesion and friction, rendering them suitable for various applications, including smart coatings for rain corrosion protection and falling raindrop energy harvesting.

Thick Architected Silicon Composite Battery Electrodes Using Honeycomb Patterned Carbon Nanotube Forests

To meet the growing performance demands for personal electronics and electric vehicles the energy density of lithium-ion batteries can be increased by incorporating thicker electrodes. We present thick “honeycomb” electrodes based on patterned, vertically aligned carbon nanotubes (CNTs) on Cu foils. Thick electrodes are created by Si deposition on >100 μm tall honeycomb patterned CNTs. Si-CNT electrodes are cycled in half-cells, demonstrating electronic connection between the Si and Cu foil via the aligned CNTs. For ~4.7 mAh cm−2 capacity the honeycomb patterning improves capacity retention (78%) over 30 cycles compared to non-patterned electrodes (58%). We attribute this improvement to the honeycomb’s ability to accommodate Si expansion, thereby reducing cracking that causes active material loss and solid electrolyte interphase instability, and to provide pathways for Li-ion transport into the electrode. The Si-CNT electrode capacity is further increased to 20 mAh cm−2 by increasing the Si loading. Finally, a fluoroethylene carbonate containing electrolyte is used to increase cell lifetime. Here, the honeycomb electrodes have a higher areal (~10.2 mAh cm−2) and retained (65%) capacity over 180 cycles, and exhibit superior rate performance to their non-patterned counterparts. Our work demonstrates the role of patterning in enabling aligned CNTs as a robust template for thick battery electrodes.

Pattern and filament optimization for 3D-printed reinforcements to enhance the flexural behavior of cement-based composites

Cement-based materials are the world's most widely utilized construction materials due to their high compressive strength. However, they need reinforcement to withstand direct or indirect tensile forces. This study evaluated the potential use of 3D-printed polymers as an alternative reinforcement in cement-based composites. Polyethylene terephthalate glycol (PETG), Polyamide (PA), and Acrylonitrile butadiene styrene (ABS) based triangular and honeycomb-patterned 3D-printed reinforcements were incorporated into cement-based composites, and their mechanical performances were compared under three-point flexural tests by considering both polymer and pattern type. Both triangular and honeycomb patterns enhanced flexural behavior. Considering all filaments, the honeycomb pattern was found more effective than the triangular one for increasing flexural strength, deflection capacity, and toughness up to 46.80%, 251.85%, and 77.66%, respectively. In the case of filament type, 3D-printed PA-type filament in a honeycomb pattern preserved flexural strength, enhanced deflection capacity, and increased flexural toughness with pseudo-deflection hardening behavior. 3D-printed honeycomb patterned reinforcements produced by PA have the opportunity to be used in the manufacture of cement-based composites.

Bio-inspired hierarchical structure of polyaniline in the pore surface of polymer film through interfacial polymerization as a smart material sensitive to pH

The bio-inspired hierarchical structure of polyaniline (PANI) was fabricated in the pore surface of polymer film through interfacial polymerization. The porous polystyrene (PS) honey-comb patterned (HCP) film containing benzoyl peroxide (BPO) was first fabricated by the breath figure (BF) method under humid conditions, further, the film was immersed into aniline hydrochloride aqueous solution for the interfacial polymerization of PANI. The interfacial polymerization of the HCP porous film led to the biomimetic growth of PANI in fractal configuration for a bio-inspired snowflake or leaf-like pattern in the pore surface. The bio-inspired structure of PANI in the HCP porous film through interfacial polymerization is explained by the diffusion-leading aggregation (DLA) by the reaction of aniline monomer into an aqueous solution and self-assembled BPO in the pore surface. The morphology of the bio-inspired PANI structure in the HCP film was highly sensitive to pH, and revealed the conductivity variation over several orders of magnitude (10-3 to 10-1 S/cm) similar to a smart material. Due to the high pH sensitivity, the film can be applied in various biomedical sensing applications.

Antibacterial Activity of Polyaniline Coated in the Patterned Film Depending on the Surface Morphology and Acidic Dopant.

We have fabricated poly(ε-caprolactone) (PCL) films with flat and honeycomb-patterned (HCP) structures to coat polyaniline (PANI) on the film surface. In addition, the effect of chemical modification of PANI by sulfuric acid (H2SO4) was also studied for antibacterial activity. The flat and HCP PCL films were obtained by simple evaporation of the solvent and via the breath figure (BF) method, respectively. The morphology and chemical composition of PANI coated on the film surface were evaluated by scanning electron microscopy (SEM) and X-ray spectroscopy (EDX). Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA) were obtained to identify the PANI coating. The wettability and conductivity of the films were also measured. Applicational aspects were evaluated by assessing antibacterial and antibiofilm activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The EDX, TGA, and FT-IR findings indicated chemical modification of PCL film by PANI and H2SO4. The conductivity of the films was increased by the coating of PANI to the patterned surface and additionally increased by the chemically modified PANI. The antibacterial activity was 69.79%, 78.27%, and 88% against E. coli, and 32.73%, 62.65%, and 87.97% against S. aureus, for flat PANI, HCP PANI, and H2SO4-treated HCP films, respectively. Likewise, the PANI coated flat, HCP, and H2SO4-treated HCP films inhibited E. coli biofilm formation by around 41.62%, 63%, and 83.88% and S. aureus biofilm formation by 17.81%, 69.83%, and 96.57%, respectively. The antibacterial activity of the HCP film was higher than that of flat PANI films, probably due to the higher coating of PANI on the HCP surface. Moreover, sulfonation of the HCP film with H2SO4 might have improved the wettability, thereby enhancing the antibacterial and antibiofilm properties. Our results showed that topographical changes, as well as doping, offer simple and cost-effective ways to modify the structural and functional properties of films.

Modified Breath Figure Methods for the Pore-Selective Functionalization of Honeycomb-Patterned Porous Polymer Films.

Recent developments in the field of the breath figure (BF) method have led to renewed interest from researchers in the pore-selective functionalization of honeycomb-patterned (HCP) films. The pore-selective functionalization of the HCP film gives unique properties to the film which can be used for specific applications such as protein recognition, catalysis, selective cell culturing, and drug delivery. There are several comprehensive reviews available for the pore-selective functionalization by the self-assembly process. However, considerable progress in preparation technologies and incorporation of new materials inside the pore surface for exact applications have emerged, thus warranting a review. In this review, we have focused on the pore-selective functionalization of the HCP films by the modified BF method, in which the self-assembly process is accompanied by an interfacial reaction. We review the importance of pore-selective functionalization, its applications, present limitations, and future perspectives.

Surfactant-free GO-PLA nanocomposite with honeycomb patterned surface for high power antagonistic bio-triboelectric nanogenerator

While triboelectric nanogenerators (TENGs) made of biomaterials are becoming significant components of self-charged monitoring healthcare systems, most of them show low output performance and poor durability. Herein, a surfactant-free graphene oxide-polylactic acid (GO/PLA) nanocomposite with customizable honeycomb patterns was, for the first time, prepared via a scalable two-step solution method to achieve a power-boosted biocompatible TENG. The first step of this method involved using a suitable solvent (such as dimethylformamide) to well disperse the GO nanoparticles into PLA. Subsequently, honeycomb patterns were induced by using a mixture of chloroform and methanol as a suitable volatile solvent/nonsolvent pair for improved phase separation. The results indicated that GO nanoparticles with large surface area and abundant electron-donating groups decorated the honeycomb patterns and significantly influenced the electro-positivity and surface properties of the PLA bio-polymer. An unprecedented antagonistic TENG ( A- TENG) based on the concave-honeycomb GO-PLA ( hc- GO/PLA) and its corresponding convex-polydimethylsiloxane ( c- PDMS) form a pair of tribo-components with antagonistic friction surfaces and generate an output power of 3.25 mW, which is 13.6 times higher than that of a flat-surface TENG ( f -TENG) without GO additives. We believe that the incorporation of functional GO nanoparticles without surfactants expands the potential applications of biocompatible A- TENG in healthcare areas thanks to its boosted output performance and persisting biocompatibility. • A new surfactant-free patterning technique for GO/PLA nanocomposite. • Pattern features are adjusted. • New design of antagonistic TENG for significantly boosting performance. • Bio A- TENG can power wearable electronics.

Fabrication and characterization of pore-selective silver-functionalized honeycomb-patterned porous film and its application for antibacterial activity

Pore-selective silver (Ag)-functionalized honeycomb-patterned (HCP) polystyrene (PS) films were fabricated via a modified breath figure method using an interfacial chemical reaction and its application for an antibacterial film using the role of micro-trapping pit was systematically studied. PS polymer solution containing ferrocene which acts as a reducing agent was cast under humid conditions containing silver nitrate (AgNO3) to induce an interfacial chemical reaction between ferrocene and AgNO3 at the water droplet/polymer solution interface. The confinement of Ag+ to the humidity is possible due to the formation of the water complex of Ag+ such as Ag+(H2O)n stabilized by the Lennard–Jones potential and electrostatic interactions. Ag+ may be carried to the polymer solution surface via the water humidity despite being a heavy metal. Scanning electron microscopy and elemental mapping analysis revealed that the pores of the obtained films were selectively coated by Ag. The contact angle of the HCP porous films was greatly decreased by the pore selective Ag functionalization, which acts as a micro-trapping pit for the antibacterial activity. The antibacterial activity of the film against Escherichia coli and Staphylococcus aureus was assessed by the micro-dilution method, selective fluorescence imaging, and crystal violet assay. The study of BF for a functional HCP film by accompanying an interfacial chemical reaction for the pore-selective Ag functionalization shows that specific metal or inorganic materials could be pore-selectively functionalized by a similar method under several conditions, thus potentially giving the HCP films various applications.

Anisotropic electrospun honeycomb polycaprolactone scaffolds: Elaboration, morphological and mechanical properties

Tissue engineering technology requires porous scaffolds, based on biomaterials, which have to mimic as closely as possible the morphological and anisotropic mechanical properties of the native tissue to substitute. Anisotropic fibrous scaffolds fabricated by template-assisted electrospinning are investigated in this study. Fibers of electrospun Polycaprolactone (PCL) were successfully arranged spatially into honeycomb structures by using well-shaped 3D micro-architected metal collectors. Fibrous scaffolds present 2 × 4 mm2 wide elementary patterns with low and high fiber density areas. Distinct regions of the honeycomb patterns were analyzed through SEM images revealing different fiber diameters with specific fiber orientation depending on the regions of interest. Tensile test experiments were carried out with an optical observation of the local deformation at the pattern scale, allowing the determination and analysis, at small and large deformation, of the axial and transverse local strains. The honeycomb patterned mats showed significantly different mechanical properties along the two orthogonal directions probing an anisotropic ratio of 4.2. Stress relaxation test was performed on scaffolds at 15% of strain. This measurement pointed out the low contribution of the viscosity of about 20% in the mechanical response of the scaffold. An orthotropic linear elastic model was consequently proposed to characterize the anisotropic behavior of the produced patterned membranes. This new versatile method to produce architected porous materials, adjustable to several polymers and structures, will provide appealing benefits for soft regenerative medicine application and the development of custom-made scaffolds.

Pore-selective modification of the honeycomb-patterned porous polystyrene film with poly(N-isopropylacrylamide) and application for thermo-responsive smart material

Porous honeycomb-patterned (HCP) polystyrene (PS) film was pore-selectively functionalized by carboxylic acid group and modified by thermo-responsive poly (N-isopropylacrylamide) (PNIPAAm) to extend the application of HCP polymer films. The carboxylic acid functionalized film was obtained by a reactive breath figure method by casting a formylated PS (PS-CHO) solution under aqueous humid conditions containing oxone, which oxidized aldehyde into carboxyl acid at the interface of a water droplet/polymer solution accompanying an interfacial reaction. The fabricated film was reacted with amine-terminated poly (N-isopropylacrylamide) in aqueous solution for the pore-selective PNIPAAm modified HCP film. Temperature-dependent pore-surface morphology and wettability of the film were observed by scanning electron microscopy and contact angle measurement analysis after immersing into the water at below and above the lower critical solution temperature of PNIPAAm. The increase of temperature induced the pore-surfaces of the film to a higher rugged surface morphology and more hydrophobicity. The temperature-dependent capture ability of Ag nanoparticles in the pore-selective PNIPAAm modified HCP film was studied by immersing the film in aqueous solution containing Ag nanoparticles at 25 °C and 40 °C, which resulted in a higher capturing at higher temperature.

Effect of ferrocene on the fabrication of honeycomb-patterned porous polystyrene films and silver functionalization of the film

Honeycomb-patterned (HCP) porous polystyrene (PS) film was fabricated by the breath figure method with inclusion of ferrocene in the PS solution for silver (Ag)-functionalization. Ag-functionalized HCP porous PS film was obtained by immersing the fabricated film in aqueous silver nitrate solution through interfacial reduction by ferrocene. The addition of ferrocene in the polymer solution also affected the morphology of the HCP porous film during the fabrication process. Depending on the used ferrocene concentration, morphology of the obtained Ag morphology on the film surface was different. By increasing the ferrocene concentration the reduced silver particles changed to silver nanowire without much aggregation and also increased the conductivity of the films. This method of silver-functionalization on the polymer film unleashes the futuristic applications in interdisciplinary fields such as substrates for Raman scattering and antibacterial studies.

Three Dimensional Honeycomb Patterned Fibrinogen Based Nanofibers Induce Substantial Osteogenic Response of Mesenchymal Stem Cells

Stem cells therapy offers a viable alternative for treatment of bone disorders to the conventional bone grafting. However clinical therapies are still hindered by the insufficient knowledge on the conditions that maximize stem cells differentiation. Hereby, we introduce a novel 3D honeycomb architecture scaffold that strongly support osteogenic differentiation of human adipose derived mesenchymal stem cells (ADMSCs). The scaffold is based on electrospun hybrid nanofibers consisting of poly (L-lactide ε-caprolactone) and fibrinogen (PLCL/FBG). Classical fibers orientations, random or aligned were also produced and studied for comparison. The overall morphology of ADMSC’s generally followed the nanofibers orientation and dimensionality developing regular focal adhesions and direction-dependent actin cytoskeleton bundles. However, there was an initial tendency for cells rounding on honeycomb scaffolds before ADMSCs formed a distinct bridging network. This specific cells organization appeared to have significant impact on the differentiation potential of ADMSCs towards osteogenic lineage, as indicated by the alkaline phosphatase production, calcium deposition and specific genes expression. Collectively, it was observed synergistic effect of nanofibers with honeycomb architecture on the behavior of ADMSCs entering osteogenic path of differentiation which outlines the potential benefits from insertion of such bioinspired geometrical cues within scaffolds for bone tissue engineering.

Bio-inspired low frictional surfaces having micro-dimple arrays prepared with honeycomb patterned porous films as wet etching masks.

Some kinds of snakes have micro-dimple arrays on their skins and show low frictional properties. Cost-effective and simple preparation methods of surfaces having micro-dimple arrays without burrs have been required. In this study, micro-dimple arrays were successfully prepared on aluminum plates and pipes by using honeycomb patterned porous films as wet etching masks. Resulting surfaces having 5 and 8 μm dimple diameters show low frictional coefficients compared with polished surfaces at a fluid lubrication regime.

Cost-effective nanostructured thin-film solar cell with enhanced absorption

Nanostructured transparent conductive electrodes are highly interesting for efficient light management in thin-film solar cells, but they are often costly to manufacture and limited to small scales. This work reports on a low-cost and scalable bottom-up approach to fabricate nanostructured thin-film solar cells. A folded solar cell with increased optical absorber volume was deposited on honeycomb patterned zinc oxide nanostructures, fabricated in a combined process of nanosphere lithography and electrochemical deposition. The periodicity of the honeycomb pattern can be easily varied in the fabrication process, which allows structural optimization for different absorber materials. The implementation of this concept in amorphous silicon thin-film solar cells with only 100 nm absorber layer was demonstrated. The nanostructured solar cell showed approximately 10% increase in the short circuit current density compared to a cell on an optimized commercial textured reference electrode. The concept presented here is highly promising for low-cost industrial fabrication of nanostructured thin-film solar cells, since no sophisticated layer stacks or expensive techniques are required.

A Comparative Study of Fibroblast Behaviors under Cyclic Stress Stimulus and Static Culture on 3D Patterned Matrix

Mechanical stress and patterned surface of the scaffolds has been recognized as a crucial factor in determining cell functionality and tissue development, which in turn can direct the cell responses. In this study, fibroblasts M-3T3 in three-dimensional (3D) honeycomb patterning Chitosan/Poly(L-Lactic Acid) (CS/PLLA) composites was stimulated by a 15% sinusoidal (1 Hz) strain applied by a biodynamic test instrument. The effects of mechanical stimulus on the cell proliferation and basic Fibroblast Growth Factor (bFGF) secretion were studied in comparison to the non-strain groups and blank control. Results show that fibroblasts are able to sense the mechanical stimulation and respond, resulting in a time dependent increase of bFGF secretion and promoting cell proliferation. Moreover, the cells seeded in the scaffolds showed a higher cell proliferation and bFGF secretion. These findings support the hypothesis that suitable mechanical stimulus has positive effect on fibroblasts, and such a 3D honeycomb patterned scaffold may play a positive role in regulating cell behaviors in vitro.

Biomedical Application of Surface Science: Honeycomb Patterned Polymer Films as Novel Biomedical Materials

This report describes universities-industries collaborations on biomedical applications of self-organized honeycomb-patterned polymer films, which are prepared by using physical surface phenomena based on water droplet condensation during evaporation processes of polymer film casting. The film company has established engineering processes of regularly porous polymer film fabrication. The textile company has developed high-performance adhesion preventing polymer films having asymmetric nano-honeycomb structure under collaboration with the film company. Covered biliary stents are newly developed and released by the medical device company. Honeycomb-patterned polymer films are supplied to the medical device company from the film company.

Semipolar GaInN/GaN light‐emitting diodes grown on honeycomb patterned substrates

AbstractExcellent semipolar GaN material quality can be obtained by growing inverse GaN pyramids on full 2 inch c‐plane sapphire when combining the advantages of defect reduction via FACELO and selective area growth for faceted surfaces. The nearly defect free material is obtained by structuring the mask into a honeycomb pattern. When realizing full GaInN/GaN LED structures on those templates a relatively broad emission is observed during electroluminescence measurements.Furthermore, the dominant wavelength is found to be dependent on the applied current density. The pronounced shift is in good agreement with the wavelength shift along one single facet. Gas phase diffusion during the active area growth is believed to be the main reason for the varying indium content. The homogeneity could be influenced by changing the reactor pressure during the active area growth (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Production of mesoscopically patterned cellulose film

Honeycomb and stripe patterned films were prepared from cellulose triacetate (CTA)/chloroform solution, as a result of the self-organization of the polymer during evaporation of the solvent. The honeycomb patterned CTA films were prepared by two methods, a direct pattern formation method and a transcription method. The latter method gave a well-organized microporous honeycomb pattern. Both types of patterned CTA films were saponified to yield the corresponding patterned cellulose films.