Honeycomb-structured Porous Films Research Articles

Honeycomb-Structured Porous Films from Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate): Physicochemical Characterization and Mesenchymal Stem Cells Behavior.

Surface morphology affects cell attachment and proliferation. In this research, different films made of biodegradable polymers, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-HV), containing different molecular weights, with microstructured surfaces were investigated. Two methods were used to obtain patterned films—water-assisted self-assembly (“breath figure”) and spin-coating techniques. The water-assisted technique made it possible to obtain porous films with a self-assembled pore structure, which is dependent on the monomer composition of a polymer along with its molecular weight and the technique parameters (distance from the nozzle, volume, and polymer concentration in working solution). Their pore morphologies were evaluated and their hydrophobicity was examined. Mesenchymal stem cells (MSCs) isolated from bone marrow were cultivated on a porous film surface. MSCs’ attachment differed markedly depending on surface morphology. On strip-formed stamp films, MSCs elongated along the structure, however, they interacted with a larger area of film surface. The honeycomb films and column type films did not set the direction of extrusion, but cell flattening depended on structure topography. Thus, stem cells can “feel” the various surface morphologies of self-assembled honeycomb films and change their behavior depending on it.

Preparation of porous urushiol-based polybenzoxazine films with chemical resistance by breath figures method

A novel benzoxazine monomer (UPA) had been synthesized by the reaction of urushiol with formaldehyde and propylamine. From the ring-opening reaction of UPA, the corresponding new biobased resin polybenzoxazine (PUPA) was obtained. The PUPA was used to fabricate honeycomb-structured porous films using the breath figures technique. The obtained films were characterized by scanning electronic microscopy. The results showed that PUPA films were highly ordered porous films. Furthermore, the PUPA porous films possess excellent acid, alkali and organic solvent resistance properties.

Rhodamine B-decorated poly(hydroxypropyl acrylate) and their effects on the self-assembly of breath figure arrays

Novel poly(hydroxypropyl acrylate)-co-poly(hydroxypropyl acrylate)-rhodamine B (PHPA-co-PHPA-RhB) hydrophilic copolymers were synthesized via radical polymerization in this paper. And then the honeycomb-structured porous films were fabricated by dropping the (PHPA-co-PHPA-RhB) copolymers and PS solution on glass substrates by breath figure method (BFM). The effects of solvent, hydrophilic copolymers’ molecular weight, the proportion of hydrophilic copolymers and hydrophobic polymers on the formation of porous films were investigated. The porous films were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), spectrofluorometer and confocal laser scanning microscope (CLSM). The results show that PHPA-co-PHPA-RhB and PS solutions can form regular honeycomb porous films; the average diameter of the films pore decreases with the proportion of hydrophobic polystyrene increased. Similar regular was also found when the molecular weight of PHPA-co-PHPA-RhB was enhanced. Furthermore, the fluorescence properties of the porous films were also investigated in this study.

Porous membranes based on poly(ether imide)-graft-poly(vinyl acetate) as a scaffold for cell growth

A series of poly(ether imide)-graft-poly(vinyl acetate) copolymers with different molecular weights were synthesized successfully and characterized using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimeter, thermogravimetric analysis, and X-ray photoelectron spectroscopy analyses. These copolymers were used to fabricate honeycomb-structured porous films using the breath figure templating technique. The surface topology and composition of the highly ordered pattern film were further characterized using a scanning electron microscopy. The results indicated that the poly(ether imide)-graft-poly(vinyl acetate) graft molecular weight ratio influenced the breath figure film surface topology. A model was proposed to elucidate the stabilization process of the poly(ether imide)-graft-poly(vinyl acetate)-aggregated architecture on the water droplet–based templates. In addition, cell viability has been investigated via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test, and the cell morphology on the honeycomb-structured poly(ether imide)-graft-poly(vinyl acetate) porous film has been evaluated using a fluorescence microscope. This porous film is shown to be suitable as a matrix for cell growth.

CO2‐Induced Tunable and Reversible Surface Wettability of Honeycomb Structured Porous Films for Cell Adhesion

Honeycomb-patterned porous films with different structures are generated from polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) using a breath figure technique. CO2-induced reversible surface wettability is then achieved by alternate introduction and removal of CO2. For the first time, original hydrophobic surfaces are directly used as scaffolds for cell culture with CO2 atmosphere to enhance the interaction with cells, thus resulting in better cell attachment and proliferation. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Rhodamine B-loaded star polystyrenes and their luminescent honeycomb-patterned porous films

Two types of star polystyrene (SPS) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization: three-arm star polystyrene (TSPS) and five-arm star polystyrene (FSPS). Honeycomb-structured porous films were fabricated by drop-casting of the SPS solutions on glass substrates. The regular honeycomb-patterned porous films were successfully constructed from the SPS solution casting process, and the pore diameter increased with the molecular weight of the SPS enhanced at appropriate molecular weight range. Furthermore, rhodamine B (RhB) was loaded into SPS to endow the microporous film with fluorescence. The RhB-loaded SPS film exhibits a strong and uniform red emission image.

Fabrication of flexible pressure sensors with microstructured polydimethylsiloxane dielectrics using the breath figures method

Abstract

Fabrication of honeycomb-structured poly(ethylene glycol)-block-poly(lactic acid) porous films and biomedical applications for cell growth

A series of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) copolymers with a hydrophobic PLA block of different molecular weights and a fixed length hydrophilic PEG were synthesized successfully and characterized. These amphiphilic block copolymers were used to fabricate honeycomb-structured porous films using the breath figure (BF) templating technique. The surface topology and composition of the highly ordered pattern film were further characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. The results indicated that the PEG-to-PLA block molecular weight ratio influenced the BF film surface topology. The film with the best ordered pores was obtained with a PEG-to-PLA ratio of 2.0×103:3.0×104. The self-organization of the hydrophilic PEG chains within the pores was confirmed by XPS and fluorescence labeled PEG. A model is proposed to elucidate the stabilization process of the amphiphilic PEG-PLA aggregated architecture on the water droplet-based templates. In addition, GFP-U87 cell viability has been investigated by MTS test and the cell morphology on the honeycomb-structured PEG-PLA porous film has been evaluated using phase-contrast microscope. This porous film is shown to be suitable as a matrix for cell growth.

Photoactive, Porous Honeycomb Films Prepared from Rose Bengal-Grafted Polystyrene

Honeycomb-structured porous polymer films based on photosensitizer-grafted polystyrene are prepared through the breath figure process. Rose Bengal (RB) photosensitizer is first attached to a well-defined poly(styrene-stat-4-vinylbenzyl chloride) statistical copolymer, synthesized by nitroxide-mediated radical polymerization. The RB grafted poly(styrene-stat-4-vinylbenzyl chloride) (ca. 20,000 g mol(-1) molar mass, 1.2 dispersity) leads to porous polymer films, with a hexagonal pore pattern, while a simple mixture of poly(styrene-stat-4-vinylbenzyl chloride) and the insoluble RB photosensitizer produced unstructured, nonporous films. The RB-grafted honeycomb films, compared with the corresponding nonporous flat films, are more efficient for oxidation of organic molecules via singlet oxygen production at a liquid/solid interface. The oxidations of 1,5-dihydroxynaphthalene to juglone and α-terpinene to ascaridole are followed in ethanol in the presence of both types of films. Oxidation of the organic molecules is a factor 5 greater with honeycomb compared to the nonporous films. This gain is ascribed to two factors: the specific location of the polar photosensitizer at the film interface and the greater exchange surface, as revealed by fluorescence and scanning electron microscopies.

Honeycomb-Structured Porous Films Prepared from Polymer Nanocomposites of Gold Nanorods

Honeycomb-patterned porous films have attracted the increasing interests of material scientists due to their unique structure and properties. In this work, we reported the synthesis of oil soluble gold nanorods (GNRs) using a two-phase method and the preparation of honeycomb-structured porous films of polymer nanocomposites. The prepared GNRs show interfacial activities to induce the formation of honeycomb structures. Both GNRs and polymer are indispensable for the fabrication of ordered honeycomb patterns. The influences of GNRs concentration and the solvent were investigated. GNRs incorporated honeycomb films have shown strong absorbance in both visible and near-infrared wave bands and may have potential application as new photonic band gap materials.

Honeycomb Structured Porous Films Prepared by the Method of Breath Figure: History and Development

Solvent evaporation induced cooling of a solution surface will result in condensation of water vapor, which is known as breath figure. The condensed water droplets arrange normally into hexagonal packing to template the solution surface. After complete evaporation of solvent and water, hexagonally ordered porous array (breath figure array, BFA) can be left on the solute matrix by the imprints of the water droplets. An optimal BFA can be obtained by adjusting the controlling factors in a breath figure fabrication such as solvent, water vapor and material. The solvent is usually volatile organic solvent, and the water vapor can be dynamic or static; the solute can be homopolymer, block copolymer, polymer blend, polymer/additive mixture, polymer/inorganic hybrid or even pure nano particles. At the same time, hierarchically ordered structural patterns can be fabricated with such materials as building blocks by combining breath figure method with other microfabrication strategies. Moreover, specific fabrication procedures different from typical breath figure condition can be used for particular preparations. Progress in this field is summarized and discussed. Especially, some applications and post treatments of BFAs are introduced too. Keywords: Breath figure, honeycomb, ordered porous pattern, post-treatment, application, Porous Films, photonics, biotechnology, self-assembled, microfabrication strategies, Solvent, Humidity (Airflow), Carbon disulfide, Polymers, Nanoparticles

Honeycomb-Structured Porous Films Controlled by the Temperature of Water Bath

The highly ordered porous films were fabricated from the solution of polystyrene with one carboxyl terminal group in carbon disulfur in a chamber with a water bath. It is found that the pore size can be readily controlled by changing the temperature of water bath. The pore size increases with an increase in the water-bath temperature in a given range. And the porous film from the “dilute” solution can be readily formed even at a low relative humidity (RH), while the porous film from the “concentrated” solution can be fabricated only at a rather high RH. The regularity of porous film becomes better at the higher RH and higher concentration. It suggests that there exists a synergetic effect of solution concentration and RH on the formation of porous film. These phenomena are explained by the slow evaporation rate of the solvent under the conditions.

Microwells with Patterned Proteins by a Self‐Assembly Process Using Honeycomb‐Structured Porous Films

Reactive honeycomb-structured porous films are obtained using amphiphilic block copolymer microwells. This one-step process leads to high functionality inside the pores suitable for the attachement of proteins. As a result, a regular streptavidin array is created by using simple breath figure methology (see figure).

Honeycomb-Structured Porous Films from Polypyrrole-Containing Block Copolymers Prepared via RAFT Polymerization as a Scaffold for Cell Growth

Honeycomb-structured porous films were prepared using customized amphiphilic block copolymers, synthesized by RAFT polymerization. Pyrrole was templated along an amphiphilic block copolymer, composed of polystyrene and poly(acrylic acid). Subsequent oxidation of pyrrol to polypyrrole, resulted in the formation of a soluble polypyrrole-containing polymer. Gel permeation chromatography and dynamic light scattering studies confirmed the solubility of the resulting customized amphiphilic block copolymer, in both water and organic solvent, forming either micelles or inverse aggregates. Porous films with a hexagonal array of micron-sized pores were generated with the polymer, using the breath figures templating technique. The resulting films were found to be non-cytotoxic and hence suitable as scaffolds for tissue engineering. Initial fibroblast cell culture studies on these scaffolds demonstrated a dependency of cell attachment on the pore size of scaffolds.

Gold-Loaded Organic/Inorganic Nanocomposite Honeycomb Membranes

RAFT polymerization was used to prepare polystyrene – poly(4-vinyl pyridine) block copolymers, PSn-b-P(4VP)m. Well-defined block copolymers were obtained despite some indications of hydrolysis of the RAFT endgroup during synthesis. The block copolymer PS70-b-P(4VP)55 was self-assembled into micellar structures in dichloromethane, leading to nanoparticles with hydrodynamic diameters of 70 nm. The micelles were loaded with HAuCl4 and, upon reduction, micellar gold-containing nanoparticles with hydrodynamic diameters of 240 nm were obtained. These nanoparticles were employed in the preparation of honeycomb-structured porous films by means of the breath figures technique to yield gold nanocomposites with a hexagonal porous array.

Biomimetic Honeycomb-Structured Surfaces Formed from Block Copolymers Incorporating Acryloyl Phosphorylcholine

We report the preparation of biomimetic honeycomb-structured porous films. These regular arrays were obtained by casting block copolymers composed of polystyrene and poly(acryloyl phosphorylcholine), so that they mimicked a cell membrane. The size of the pores and regularity of the hexagonal array is strongly dependent on the block length. The block copolymers were prepared via RAFT (reversible addition fragmentation transfer) polymerization leading to well-defined products with a good control over block sizes.

Formation of Regular Honeycomb-Patterned Porous Film by Self-Organization

Regular honeycomb-structured porous films can be prepared by the casting of a polymer solution under humid conditions. The origin of these pores is `empty' water droplets, which condense from the humid atmosphere onto the solution. The water droplets self-organize into a regular array and serve as a highly regular template for the precipitating polymer. The pore size can be controlled by the casting conditions as well as by the polymer used. A spherical-shaped polymer is required to support a high regularity. These specially designed polymers can easily be prepared by controlled radical polymerization techniques.