Honeycomb-patterned Porous Films 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.

Novel Capturer-Catalyst Microreactor System with a Polypyrrole/Metal Nanoparticle Composite Incorporated in the Porous Honeycomb-Patterned Film.

A composite of polypyrrole/metal nanoparticles (PPy/MNPs) was selectively incorporated into the pores of a honeycomb-patterned porous polycaprolactone polymer film to fabricate a novel capturer-catalyst microreactor system. This fabrication involved a modified breath figure method, where the polymer solution containing metal ions as an oxidizing agent was cast under humid conditions along with the pyrrole monomer through an interfacial reaction in a one-step in situ process. The higher hydrophilicity of the metal ions compared to the polymer solution led to their self-assembly around the pore surface, resulting in the selective incorporation of the PPy/MNP composite into the porous film. Copper (Cu), silver (Ag), and gold (Au) were used for the PPy/MNP fabrication. Various methods characterized the fabricated film. Strong catalytic degradations of methylene blue and methyl orange were obtained with PCL-PPy/MNPs. Recycling experiments showed no loss of activity even after five cycles of recycling. Comparative analysis of PCL-PPy, PCL-MNP, and PCL-PPy/MNP results indicated the synergistic action of PPy and MNPs in dye degradation. High-performance liquid chromatography and mass spectroscopy analyses confirmed dye degradation after treatment with a fabricated microreactor. PPy might have acted as a capturer of the dye molecule and MNPs as a catalyst, thereby enhancing the efficiency of dye degradation. Additionally, the PCL-PPy/Cu composite exhibited strong antimicrobial properties against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) with no cytotoxicity as measured by the MTT assay. Therefore, the fabricated microreactor film has promising applications in various fields.

Synergistic control of breath figures on Styrene-Butadiene-Styrene films by poly-2-ethyl-2-oxazoline capped CaCl2 loaded mesoporous silica particles

The addition of hydrophilic components (CaCl2, poly-2-ethyl-2-oxazoline (PEOX) or mesoporous silica particles (MSP)) into Styrene-Butadiene-Styrene (SBS)/chloroform solution was shown to affect the resulting breath figure patterns in terms of pore size, pore shape and order. Honeycomb-patterned porous SBS polymer films were prepared by adding 30 wt% PEOX capped, CaCl2 loaded mesoporous silica particles into SBS solution. The long-range order observed with a pore diameter of ∼3.6 µm in the breath figure pattern at RT and 50–70% RH was attributed to the synergistic contributions of each component. CaCl2 promotes the condensation of water vapor and the nucleation of many water droplets on the polymer solution. When localized in a uniformly swollen layer of PEOX around MSP, easier nucleation together with stabilization of water droplets by MSP and PEOX leads to hexagonally-ordered breath figures. The results demonstrate the addition of hydrophilic components as an easy tool to tune breath figure patterns at relatively low humidity and their synergistic contributions.

Honeycomb-patterned porous graphene film for electrochemical detection of dopamine

Development of simple, low-cost and facile electrochemical sensor for DA detection is of great significance for the study and treatment of several neurological and psychiatric disorders. Herein, an innovative integration of honeycomb-patterned ordered porous structure with conductive reduced graphene oxide (rGO) was realized through the convenient breath figure method, in which the self-assembly of nontoxic and inexpensive water droplets were involved. Graphene oxide (GO) can be transferred to organic phase by surfactant via a simple self-assembly process to acquire the GO/surfactant complex, which was used as the casting solution in the breath figure method, and thus the skeleton of the porous structure. After electrochemical reduction, honeycomb-patterned porous rGO film was obtained. The prepared rGO-based porous structure modified electrode exhibited a high sensitivity of 1.18 μA/μM and low detection limit of 0.12 μM to DA detection, which are 2.5 and 0.07 folds to corresponding flat films, and are also comparable or even exceeding several functionalized graphene, GO or rGO composites sensor. In addition, excellent anti-interference, reproducibility, repeatability, long-term stability and good accuracy for DA detection in real samples were shown. Importantly, the porous structure can be easily adjusted by changing the preparation conditions, thereby regulating or optimizing the electrochemical sensing performance.

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.

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.

Thermo-responsive release of rhodamine B in the pore-selective poly(N-isopropylacrylamide) immobilized honeycomb-patterned porous film

Thermo-responsive release of rhodamine B in the pore-selective poly(N-isopropylacrylamide) immobilized honeycomb-patterned porous film

Hierarchical Nano/Micro Moth Eyelike Polymer Film Using Solid/Liquid Interfacial Reaction at Room Temperature.

A simple pathway for the fabrication of real moth eyelike patterned (MEP) polymer film with a double-layered nano/microhierarchical structure is demonstrated through a solid/liquid interfacial reaction at atmospheric conditions. A convex-structured polyvinyl alcohol (PVA) film containing CdCl2 was first fabricated using a self-organized honeycomb-patterned porous film as a template. The CdCl2/PVA convex film was immersed into Na2S/ethanol solution to facilitate the reaction between CdCl2 and Na2S at the solid/liquid interface, which led to the functionalization of CdS nanoparticles in the convex-structured PVA film. The tunable introduction of interfacial reaction resulted in the formation of a CdS moth eyelike nanoarray on the top surface of the PVA convex microarray, which mimicked the real moth eye (PVA-CdS MEP). PVA-CdS MEP film with a double moth eyelike structure showed improved antireflective property in comparison with flat and convex-structured PVA films. The PVA-CdS MEP film showed photoresponse under simulated solar light radiation and flexible duration after 500 cycles of folding.

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.

Morphological, optical and wettability characterization of honeycomb patterned films based on self-assembling copolymer under thermal annealing

A series of honeycomb-patterned porous films based on self-assembly block copolymers with different hydrophilic blocks were prepared using the breath figure (BF) method. The variation of hydrophilic moieties into the block copolymers provokes a response in the pore diameter size dispersity and in the surface pore distribution entropy. The morphological properties are examined using SEM and AFM microscopies, wettability properties were also studied. The distribution of the pores at the surface and shape variations of the structured films were studied by Raman spectroscopy before and after thermal annealing. We report a significant increase of the order and dispersity narrowing of the pores after thermal annealing which affects the water contact angle (WCA). These results were attributed to the process mechanism of the polymer chain self-assembly of the different hydrophilic moieties as a result of thermal annealing at temperatures below the glass transition temperature (Tg).

Highly ordered porous PLA films prepared by breath figure method

Honeycomb-patterned porous biodegradable PLA film can be successfully prepared by the Breath Figure (BF) method, which is a self-assembly template and low-cost process. In this research, the fabrication was designed to create a convenient and simple process aimed at meeting commercial requirements. Production of regularly ordered pattern microporous film is carried out in a closed system with optimum conditions. Thus, important production factors —that is, the starting polymer concentration in solution, the type of solvent (which affects the solvent evaporation rate), and the relative humidity of the closed chamber —were investigated to identify the optimum conditions. The results showed that highly ordered porous film with smaller average pore size of 23.29±4.55 µm on strut was generated (19.98±2.82 µm) when high PLA concentration (10% wt PLA) in dichloromethane with 80-85% RH relative humidity was applied.

Fabrication of moth eye-like patterned polystyrene films and their functionalization with polyaniline via interfacial reaction

Moth eye-like patterned (MEP) polystyrene (PS) films with a hexagonal array of microdomes mimicking natural moth eye were fabricated by pouring a PS solution on a honeycomb-patterned porous polyvinyl alcohol film using as a template. The surface of microdomes on the PS MEP film containing benzoyl peroxide (BPO) was functionalized with polyaniline (PANI) through interfacial reaction by using aniline hydrochloride to enhance their functionality of the MEP patterned film. The PANI functionalization on the MEP film was confirmed by UV–visible spectroscopy, scanning electron microscopy and EDX analysis.

Fabrication of robust honeycomb patterned porous films by thermochemical cross-linking of polyimide

Robust honeycomb patterned porous (HCP) polymer films resistant to a wide range of organic solvents were obtained using polyimide (PI) by thermochemical cross-linking. For the robust PI HCP film, PI HCP film was fabricated via breath figure method, treated by aq. KOH to induce imide ring cleavage, and followed by re-imidization using heat treatment at 120 °C. The robust PI HCP film was resistant to common organic solvents such as chloroform, etc. over than 20 h, while the pristine PI HCP film solubilized immediately. Morphology analyses of the robust PI HCP films showed good retention of HCP morphology without wreckage from the pristine films even after 20 h immersion in organic solvents. The film can be used as a robust template in soft lithography.

Selective Coating of SnS on the Bio‐Inspired Moth‐Eye Patterned PEDOT:PSS Polymer Films

AbstractA new strategy for the selective coating of tin sulfide (SnS) on the surface of moth‐eye patterned (MEP) conducting polymer film is studied by considering the optical properties of the antireflective moth‐eye pattern and flexibility of polymer films. The semiconductor SnS is selectively coated on the surface of MEP microdomes of poly(3,4‐ethylenedioxythiophene) poly(styrene‐sulfonate) (PEDOT:PSS) film. The SnS coated MEP film is obtained by using pore selectively SnS thin layer functionalized polystyrene honeycomb‐patterned porous (HCP) film as a template. Aqueous PEDOT:PSS solution is poured on the SnS functionalized HCP films and detached for the fabrication of SnS coated MEP films. The films show a satisfactory photo‐responsive property under solar stimulated light illumination due to the antireflective MEP structure of PEDOT film and homogenous SnS coating on the surface of the conducting polymer.

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.

Smart Honeycomb-Patterned Porous Films: Fabrications, Responsive Properties, and Applications

Smart Honeycomb-Patterned Porous Films: Fabrications, Responsive Properties, and Applications

Pore‐Selective SnS Functionalization in Honeycomb‐Patterned Films by a Breath Figure Process Accompanied by Chemical Reaction

AbstractA new fabrication process for the pore‐selective functionalization of honeycomb‐patterned porous (HCP) films is demonstrated by a modified breath figure method accompanied by an in situ chemical reaction. A polymer solution containing one reactant is cast under humid conditions containing counter reactant to facilitate a chemical reaction at condensed droplet/polymer solution interface, which results in the pore‐selective functionalization of HCP films. Polystyrene (PS) solution containing tin(II) chloride is cast under humid conditions containing aqueous hydrogen sulfide for the formation of tin sulfide (SnS)‐functionalized PS HCP films. H2S humidity is generated by pumping ambient air through the aqueous sodium sulfide solution. Scanning electron microscopy, transmission electron microscopy, and elemental mapping analyses indicate the formation of SnS as thin layers selectively in the pores of PS HCP films.

Fabrication of pore-selective carboxyl group functionalized polyimide honeycomb-patterned porous films using KOH humidity

Carboxyl group functionalization in honeycomb-patterned porous (HCP) films was obtained by breath figure process using polyimide (PI) which can react with KOH humidity at the polymer solution/aqueous alkali droplet interface to form carboxyl groups. PI containing CO-NR2 imide ring group reacts with KOH for imide ring-cleavage reaction by interfacial reaction. In order to obtain pore-selective carboxyl group functionalized PI HCP films, we have suggested a new strategy introducing KOH humidity with time interval after using initial water humidity during breath figuring process. The carboxyl group functionalized pores can be applied to obtain ordered microarray of biological and inorganic materials, which have potential applications in biosensors, separations, medical biology, etc.

Honeycomb-Patterned Polyimide Film as a Versatile Coating for High-Performance Dielectric Material.

A honeycomb-patterned porous film was conveniently prepared by means of the microemulsion method and then used as an effective coating for improving the dielectric properties and water resistance of polyimide (PI) film while maintaining its mechanical properties. The dielectric properties could be regulated by tuning the structure of the porous film through controlling its formation conditions. When suitable conditions were used, the prepared composite PI film exhibited a significant reduction of 28.3 % in its dielectric constant and 9.48-54.99 % in dielectric loss accompanied by an extremely low water uptake of 0.62 % relative to the 2.47 % of flat PI film. The composite PI film also displayed excellent durability under moist conditions, as the dielectric constant was still below 2.4 after exposure to 75 % relative humidity for more than 12 h. This provides a novel method to improve and control the dielectric properties of materials. It also suggests that this film is a suitable candidate for coating dielectric materials in high-humidity environments.

Honeycomb-patterned porous films fabricated via self-organization of Tb complex-loaded amphiphilic copolymers.

Amphiphilic copolymers, poly(styrene)-block-Tb complex (PS-b-Tb complex), were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. The honeycomb structured porous films were fabricated via dropping the PS-b-Tb complex copolymer solutions on glass substrates by the breath figures method (BFM). The structure and composition of the amphiphilic copolymer PS-b-Tb complex were confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The surface morphology and elemental mapping of the highly ordered porous films were investigated by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and laser scanning confocal microscopy (LSCM). The results indicated that the solvent type and copolymer concentration can affect the surface morphology of the porous films. The average diameter of the pores in the porous films decreased with the polymer concentration and the molecular weight of the copolymers increased. The FESEM-EDX analysis further verified that the hydrophilic groups (Tb complex groups) were mainly distributed at the pore wall, instead of at the outer surface layer of the films, which was consistent with the LSCM results.