Porous Block Copolymer Research Articles

Nanoscopic catalyst-loaded porous metal oxide hollow frameworks using porous block copolymer templates for high performance formaldehyde sensors

Porous and hollow nanostructures functionalized with nanoscopic catalysts have attracted considerable interest in a wide range of applications depending on surface reactions. In this study, we present an efficient and versatile synthetic strategy of porous metal oxide hollow frameworks (HFs) decorated with noble metal nanoparticles (NPs). The key lies in the use of porous and bicontinuous polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) microparticles as templates, which feature pores on the order of several hundred nanometers in size. Homogeneous Pt loading on the surface of the porous microparticles is achieved through the preferential adsorption of Pt precursors onto the P4VP block via electrostatic interactions. Subsequent SnO2 thin film deposition and calcination ultimately yield honeycomb-like SnO2 HFs with macropores and uniform distribution of Pt NPs. The Pt NP-loaded SnO2 HFs exhibit exceptional formaldehyde (HCHO) sensing capabilities, characterized by remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm), ultra-low detection limit of 10 ppb, and remarkable cross-selectivity. These outstanding features result from their high surface area, gas permeability within porous hollow structures, and well-dispersed Pt NPs, which catalytically activate the sensor. Our study provides great promise for advancing surface catalytic reactions due to their exceptional surface area and gas permeability, paving the way for future applications.

Porous block copolymer films with self-adjustable optical transmittance and passive radiative cooling

Porous block copolymer films with self-adjustable optical transmittance and passive radiative cooling

Scalable Synthesis of Carbon Nanomembranes from Amorphous Molecular Layers.

Nanoporous carbon nanomembranes (CNMs) created by self-assembled monolayers ideally combine a high water flux and precise ion selectivity for molecular separation and water desalination. However, their practical implementation is often challenged by the availability of large epitaxial substrates, limiting the membrane up-scaling. Here, we report a scalable synthesis of CNMs from poly(4-vinylbiphenyl) (PVBP) spin-coated on SiO2/Si wafers. Electron irradiation of the amorphous PVBP molecular layers induces the formation of a continuous membrane with a thickness of 15 nm and a high density of subnanometer pores, providing a water permeance as high as 530 L m-2 h-1 bar-1, while repelling ions and molecules larger than 1 nm in size. A further introduction of a reinforced porous block copolymer layer enables the fabrication of centimeter-scale CNM composites that efficiently separate organic dyes from water. These results suggest a feasible route for large-scale nanomembrane fabrication.

Tuning the Color of Photonic Glass Pigments by Thermal Annealing.

Thermal or solvent annealing is commonly employed to enhance phase separation and remove defects in block copolymer (BCP) films, leading to well-resolved nanostructures. Annealing is of particular importance for photonic BCP materials, where large, well-ordered lamellar domains are required to generate strong reflections at visible wavelengths. However, such strategies have not been considered for porous BCP systems, such as inverse photonic glasses, where the structure (and thus the optical response) is no longer defined solely by the chemical compatibility of the blocks, but by the size and arrangement of voids within the BCP matrix. In this study, a demonstration of how the concept of "thermal annealing" can be applied to bottlebrush block copolymer (BBCP) microparticles with a photonic glass architecture is presented, enabling their coloration to be tuned from blue to red. By comparing biocompatible BBCPs with similar composition, but different thermal behavior, it is shown that this process is driven by both a temperature-induced softening of the BBCP matrix (i.e., polymer mobility) and the absence of microphase separation (enabling diffusion-induced swelling of the pores). Last, this concept is applied toward the production of a thermochromic patterned hydrogel, exemplifying the potential of such responsive biocompatible photonic-glass pigments toward smart labeling or anticounterfeiting applications.

A Molecular Photosensitizer in a Porous Block Copolymer Matrix-Implications for the Design of Photocatalytically Active Membranes.

Recently, porous photocatalytically active block copolymer membranes were introduced, based on heterogenized molecular catalysts. Here, we report the integration of the photosensitizer, i. e., the light absorbing unit in an intermolecular photocatalytic system into block copolymer membranes in a covalent manner. We study the resulting structure and evaluate the orientational mobility of the photosensitizer as integral part of the photocatalytic system in such membranes. To this end we utilize transient absorption anisotropy, highlighting the temporal reorientation of the transition dipole moment probed in a femtosecond pump‐probe experiment. Our findings indicate that the photosensitizer is rigidly bound to the polymer membrane and shows a large heterogeneity of absolute anisotropy values as a function of location probed within the matrix. This reflects the sample inhomogeneity arising from different protonation states of the photosensitizer and different intermolecular interactions of the photosensitizers within the block copolymer membrane scaffold.

Porous block copolymer separation membranes for 21st century sanitation and hygiene.

Removing hazardous particulate and macromolecular contaminants as well as viruses with sizes from a few nm up to the 100 nm-range from water and air is crucial for ensuring sufficient sanitation and hygiene for a growing world population. To this end, high-performance separation membranes are needed that combine high permeance, high selectivity and sufficient mechanical stability under operating conditions. However, design features of separation membranes enhancing permeance reduce selectivity and vice versa. Membrane configurations combining high permeance and high selectivity suffer in turn from a lack of mechanical robustness. These problems may be tackled by using block copolymers (BCPs) as a material platform for the design of separation membranes. BCPs are macromolecules that consist of two or more chemically distinct block segments, which undergo microphase separation yielding a wealth of ordered nanoscopic domain structures. Various methods allow the transformation of these nanoscopic domain structures into customized nanopore systems with pore sizes in the sub-100 nm range and with narrow pore size distributions. This tutorial review summarizes design strategies for nanoporous state-of-the-art BCP separation membranes, their preparation, their device integration and their use for water purification.

Hierarchically Porous Copolymer Film as Immobilization Matrix for Phenol Biosensor with High Sensitivity

A hierarchically porous structure of the matrix for immobilization of bioactive molecules is of crucial importance in improving the performance of electrochemical biosensors. In the present work, a block copolymer film was prepared via spinodal-decomposition-induced macro- and mesophase separation plus extraction by rinsing (SIM2PLE). The film exhibited an interconnected porous structure including macropores and mesopores. Thus, the specific surface area of the film was greatly enhanced, which was a benefit to the subsequent immobilization of enzyme. Then the resultant porous block copolymer film was adopted to construct a high-performance electrochemical biosensor to detect phenolic compounds. The as-developed phenolic biosensor exhibited a high sensitivity (3.0 × 103 mA·M–1·cm–2), quick response (<5 s), and extremely low detection limit (7 nM at an S/N ratio of 3). Moreover,a decent linear range (0.02–35 μM) was also observed. This work demonstrates that the hierarchically porous film based on copolymer...

Fabrication of Silica Membrane through Surface‐Induced Condensation on Porous Block Copolymer

AbstractNanoporous structures generated from micro‐phase separation of block copolymers (BCPs) have been used as templates for fabrication of inorganic materials through atomic layer deposition (ALD), chemical vapor deposition, sol‐gel process, and electrodeposition. However, the previous deposition methods are suffering from unmanageable preparation conditions and demanding technical requirements. In this work, bioinspired synthesis was used as replicating technique to fabricate silica porous membrane on swelling‐induced polystyrene‐block‐poly (2‐vinyl pyridine) (PS‐b‐P2VP) membrane with bicontinuous nanopores. It was found that silica nanoporous membranes were successfully obtained on PS‐b‐P2VP under benign conditions (near‐neutral pH, low temperature, and ambient pressure) from tetraethoxysilane (TEOS). Moreover, the thickness of silica films could be regulated by the amount of water in the TEOS solution. The mechanism could be inferred that pyridine groups in P2VP domains can act as a catalyst for the insertion and polymerization reactions of silanol from hydrolysis of TEOS to form silica due to the hydrogen bonding between pyridine groups and Si‐OH in silanol. The proposed method offers a facile and controllable synthesis strategy to fabricate nanoporous silica membrane.

A Novel Glucose Biosensor Based on Hierarchically Porous Block Copolymer Film.

Enzymatic biosensors are widely used in clinical diagnostics, and electrode materials are essential for both the efficient immobilization of enzyme and the fast electron transfer between the active sites of enzyme and electrode surface. Electrode materials with a hierarchically porous structure can not only increase the specific surface area but also promote the electron transfer, facilitating the catalysis reaction. Block copolymer is a good candidate for preparation of film with a hierarchically porous structure due to its unique characteristics of self-assembly and phase separation. In the current work, hierarchically porous block copolymer film containing both micropores and nanopores was prepared by spinodal decomposition induced phase separation. The resultant copolymer film was adopted as the electrode material to immobilize glucose oxidase (GOx) for construction of an enzyme biosensor. Scanning electron microscopy (SEM), contact angle (CA) measurements, and Fourier-transform infrared (FTIR) and electrochemical impendence spectroscopy (EIS) were adopted to investigate the microstructure of the as-developed biosensor. Results demonstrated that the hierarchically porous block copolymer film offered a favorable and biocompatible microenvironment for proteins. These as-prepared glucose biosensors possessed a wide linear range (10–4500 μM), a low detection limit (0.05 μM), quick response (2 s), excellent stability, and selectivity. This work demonstrates that hierarchically porous block copolymer film is a good matrix candidate for the immobilization of the enzyme and provides a potential electrode material to construct novel biosensors with excellent performance.

Construction of a thermoresponsive magnetic porous polymer membrane enzyme reactor for glutaminase kinetics study.

Fabrication of polymer membranes with nanopores and a confinement effect toward enzyme immobilization has been an enabling endeavor. In the work reported here, an enzyme reactor based on a thermoresponsive magnetic porous block copolymer membrane was designed and constructed. Reversible addition-fragmentation chain transfer polymerization was used to synthesize the block copolymer, poly(maleic anhydride-styrene-N-isopropylacrylamide), with poly(N-isopropylacrylamide) as the thermoresponsive moiety. The self-assembly property of the block copolymer was used for preparation of magnetic porous thin film matrices with iron oxide nanoparticles. By covalent bonding of glutaminase onto the surface of the membrane matrices and changing the temperature to tune the nanopore size, we observed enhanced enzymolysis efficiency due to the confinement effect. The apparent Michaelis-Menten constant and the maximum rate of the enzyme reactor were determined (Km = 32.3 mM, Vmax = 33.3 mM min-1) by a chiral ligand exchange capillary electrochromatography protocol with L-glutamine as the substrate. Compared with free glutaminase in solution, the proposed enzyme reactor exhibits higher enzymolysis efficiency, greater stability, and greater reusability. Furthermore, the enzyme reactor was applied for a glutaminase kinetics study. The tailored pore sizes and the thermoresponsive property of the block copolymer result in the designed porous membrane based enzyme reactor having great potential for high enzymolysis performance. Graphical abstract ᅟ.

Cyclodextrin-functionalized ordered porous block copolymer films: Preparation and property

Ordered porous block copolymer films (PBCFs) have attracted much attention because of their potential applications in several fields. In this paper, we first reported a non-destructive, controllable, and efficient approach for preparation of β-cyclodextrin (β-CD)-functionalized PBCFs (β-CD-PBCFs). The key point of the approach is to incorporate β-CD units into the hydrophilic segment of amphiphilic block copolymers before the preparation of films. β-CD-PBCFs with structural integrity and controllable pore parameters were fabricated through combining of self-assembly and breath figure methods. And then, the effective adsorption capacity of β-CD-PBCFs toward Congo red was confirmed through UV-Vis spectroscopy and was found to be affected by β-CD content and solution pH values. Adsorption kinetic results showed that the adsorption behavior of β-CD-PBCFs was consistent with the pseudo-second-order kinetic model and the chemisorption mechanism.

Hierarchical Porous Block Copolymer Separator Membranes for Ultrahigh Rate Li-Ion Batteries

High-performance energy storage systems with reliable and sustainable electrochemical properties are urgently needed to satisfy the continuously surging demand in consumer electronics, electric vehicles (EVs), and grid-scale energy storage systems (ESSs). Among the enormours energy storage systems reported to date, lithium-ion rechargeable batteries (LIBs) have still garnered a great deal of attention. The rational design and fabrication of major battery components such as anodes, cathodes, electrolytes, and separator membranes are imperative prerequisites for the development of advanced batteries. Most research activities on battery components have been devoted to the electrochemically active materials, with a especially focus on electrode materials and electrolytes. Representative results include those related to high-voltage spinel nickel manganese oxides, overlithiated layer oxides, silicon- or metal alloys, functional electrolyte additives, and solid-state electrolytes. Taking into consider the fact that electrochemical performance of the batteries is basically governed by electron/ion transport phenomena, particular attention should be paid to battery separators as well as electrodes/electrolytes, because (i) all ions particiapted in Faradaic reaction of batteries should pass through electrolyte-filled porous separator membranes and (ii) Internal short-circuit failure occurring between electrodes (which is considered as a primary cause to trigger cell fire or explosion) is basically prevented by separator membranes. Currently, commercially available separators in LIBs are manufactured using polyolefin materials. These polyolefin separators have some advantageous attributes that render them suitable for practical use in LIBs. However, their intrinsic limitations (speci fically, sluggish/nonuniform ionic flow and poor thermal stability) often raise concerns regarding ion transport and electrical isolation between the electrodes. A large number of approaches to overcome these drawbacks have been undertaken, which include ceramic-coated separators, nonwoven separators, and electrospun nano fiber separators. Unfortunately, little attention has been devoted to controlling the ion transport phenomena in a separator, despite its important role in activating the electrochemical performance of cells. Here, as a new strategy to address these challenging issues, we demonstrate new surface energy-tailored amphiphilic polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) membranes with hierarchical multiscale hyperporous structures and chemical functionality (Figure 1), as a revolutionary membrane to enable remarkable advances in cell performance far beyond those achievable with conventional separators. Among the various building blocks for use in porous membranes, BCPs have been extensively investigated because of their self-assembly-enabled nanodomains. Through spinodal decomposition, breath figures, solvent swelling, and nonsolvent-induced phase separation (NIPS), BCPs can produce precisely defined porous structures in versatile shapes. Owing to facile and effective control of membrane morphologies, NIPS process, which is also known as immersion precipitation, has attracted great attention as a promising way to fabricate large-scale membranes. In the NIPS method, final morphologies (e.g., dense or porous, symmetric or asymmetric) of the membranes can be adjusted by combining the involved mass transport phenomena with corresponding phase separation. For membrane-driven purification and separation processes, asymmetric porous structure is preferable because it endows the membranes with both permeability and selectivity. Asymmetric structures with a well-organized skin layer were explored using self-assembled BCP films. Time-controlled evaporation of volatile solvent produces a skin layer with vertically aligned cylindrical structure supported by a graded porous layer, when the BCP solution was immersed into a nonsolvent. Meanwhile, porous membranes with symmetric structures are suitable for allowing two-way ionic transport, which is essentially required for separation membranes of rechargeable power sources. The macropore size of NIPS-based BCP membranes is basically determined by polymer concentrations and solvent-nonsolvent exchange kinetics, while their nanopore size strongly depends on the compatibility between pore-forming block and nonsolvent. In particular, construction of well-defined nanoporous morphology is highly required for advanced BCP membranes. However, even though BCPs, good solvent and nonsolvent are appropriately chosen, conventional NIPS-based BCP membranes normally generate poorly-developed nanopores due to a limited compatibility between pore-forming block and nonsolvent. To date, the most common way to tune nanoporous structure is limited to variation of molecular weight of pore-forming blocks. Our strategy for tailoring high porous BCP separator membrane is based on the introduction of a surface-energy-modifying agent, which allows fine-tuning of nanoscale phase separation between the surface-modified BCPs and nonsolvent. The surface-energy-modifying agent can be easily introduced into a pore-forming block of BCPs via nucleophilic substitution reaction. Depending on the degree of substitution, the surface-energy-modifying agent contributes to tuning dual (macro-/nano-) phase separation of the BCPs, which eventually enables the fabrication of hierarchical multiscale porous block copolymer membranes. The novel block copolymer separator membrane exhibited superior rate capability and cycle performance, owing to its precisely tuned, highly developed porous structure far beyond those achievable with conventional separator membrane technologies. Figure 1

3D morphology design for forward osmosis

We propose a multi-scale simulation approach to model forward osmosis (FO) processes using substrates with layered homogeneous morphology. This approach accounts not only for FO setup but also for detailed microstructure of the substrate using the digitally reconstructed morphology. We fabricate a highly porous block copolymer membrane, which has not been explored for FO heretofore, and use it as the substrate for interfacial polymerization. The substrate has three sub-layers, namely a top layer, a sponge-like middle layer, and a nonwoven fabric layer. We generate a digital microstructure for each layer, and verify them with experimental measurements. The permeability and effective diffusivity of each layer are computed based on their virtual microstructures and used for FO operation in cross-flow setups at the macro-scale. The proposed simulation approach predicts accurately the FO experimental data.

Spontaneous emission intensity and anisotropy of quantum dot films in proximity to nanoscale photonic–plasmonic templates

We discuss results on spontaneous emission intensity and lifetime anisotropy of cadmium selenide quantum dot monolayer films placed in close proximity to a porous block copolymer based photonic–plasmonic two dimensional array. The porous block copolymer cylinders can be filled with metal nanoparticles and the concentration of these nanoparticles is varied to control both the photoluminescence intensity and lifetime of a layer of quantum dots placed above the template. Significant emission enhancement is achieved even for the quantum dot layer whose core lies about 1 nm above the template surface. Interestingly, polarised decay lifetime analysis indicates considerable emission anisotropy, as well for these quantum dots. Our results thus demonstrates how such hybrid optical materials can be created with controlled optical properties and suggests extension of this method to other novel two dimensional materials in combination with the photonic–plasmonic template.

Particles with Tunable Porosity and Morphology by Controlling Interfacial Instability in Block Copolymer Emulsions.

A series of porous block copolymer (BCP) particles with controllable morphology and pore sizes was fabricated by tuning the interfacial behavior of BCP droplets in oil-in-water emulsions. A synergistic adsorption of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) BCPs and sodium dodecyl sulfate (SDS) to the surface of the emulsion droplet induced a dramatic decrease in the interfacial tension and generated interfacial instability at the particle surface. In particular, the SDS concentration and the P4VP volume fraction of PS-b-P4VP were key parameters in determining the degree of interfacial instability, leading to different types of particles including micelles, capsules, closed-porosity particles, and open-porosity particles with tunable pore sizes ranging from 10 to 500 nm. The particles with open-porosity could be used as pH-responsive, high capacity delivery systems where the uptake and release of multiple dyes could be achieved.

Engineered Asymmetric Heterogeneous Membrane: A Concentration-Gradient-Driven Energy Harvesting Device.

Engineered asymmetric membranes for intelligent molecular and ionic transport control at the nanoscale have gained significant attention and offer prospects for broad application in nanofluidics, energy conversion, and biosensors. Therefore, it is desirable to construct a high-performance heterogeneous membrane capable of coordinating highly selective and rectified ionic transport with a simple, versatile, engineered method to mimic the delicate functionality of biological channels. Here, we demonstrate an engineered asymmetric heterogeneous membrane by combining a porous block copolymer (BCP) membrane, polystyrene-b-poly(4-vinylpyridine) (PS48400-b-P4VP21300), with a track-etched asymmetric porous polyethylene terephthalate membrane. The introduction of chemical, geometrical, and electrostatic heterostructures provides our heterogeneous membrane with excellent anion selectivity and ultrahigh ionic rectification with a ratio of ca. 1075, which is considerably higher than that of existing ionic rectifying systems. This anion-selective heterogeneous membrane was further developed into an energy conversion device to harvest the energy stored in an electrochemical concentration gradient. The concentration polarization phenomenon that commonly exists in traditional reverse electrodialysis can be eliminated with an asymmetric bipolar structure, which considerably increases the output power density. This work presents an important paradigm for the use of versatile BCPs in nanofluidic systems and opens new and promising routes to various breakthroughs in the fields of chemistry, materials science, bioscience, and nanotechnology.

Water Uptake and Proton Conductivity in Porous Block Copolymer Electrolyte Membranes

We demonstrate that the water uptake and conductivity of proton-conducting block copolymer electrolyte membranes can be controlled systematically by the introduction of pores in the conducting domains. We start with a membrane comprising a mixture of homopolymer polystyrene (hPS) and a polystyrene-b-polyethylene-b-polystyrene (SES) copolymer. Rinsing the membranes in tetrahydrofuran and methanol results in the dissolution of hPS, leaving behind a porous membrane. The polystyrene domains in the porous SES membranes are then sulfonated to give a porous membrane with hydrophilic and hydrophobic domains. The porosity is controlled by controlling ϕv, the volume fraction of hPS in the blended membrane. The morphology of the membranes before and after sulfonation was studied by scanning transmission electron microscopy (STEM), electron tomography, and resonance soft X-ray scattering (RSoXS). The porous structures before and after sulfonation are qualitatively different. Water uptake of the sulfonated membranes i...

Spiral and Mesoporous Block Polymer Nanofibers Generated in Confined Nanochannels

Spiral-like or various porous polymer nanofibers have great applications in biosensor, bioengineering, and template-fabrication of functional inorganic materials. However, the fabrication of polymer nanostructures with controllable porous or spiral morphology in one process is a big challenge. Here we first demonstrated a general and easy method to generate spiral or porous block copolymer (BCP) nanofibers by using geometric confinement of nanochannels to disturb the self-assembly of BCP while nonsolvent is induced into BCP solution. Continuous spiral polymer nanofibers and polymer nanofibers with hierarchical porous nanostructures can be easily generated within channels of anodic aluminum oxide (AAO) membranes by tuning the composition and concentration of BCP. This study first reports the influence of cylinder confinement to the arrangement of BCP micelles. These spiral and porous BCP nanostructures are not only good templates to generate functional inorganic nanostructures, but also promising candidates to create biosensors or to load catalyst because their enlarged surface area enables high guest concentrations.

Ultra‐High Optical Transparency of Robust, Graded‐Index, and Anti‐Fogging Silica Coating Derived from Si‐Containing Block Copolymers

www.advopticalmat.de Inevitable Fresnel refl ection from the interface between two optical media with different refractive indices ( η ) can decrease light absorption in photovoltaic devices and can cause undesirable glare in fldisplays. Thus, an effective antirefl ection coating (ARC) for a higher optical transmittance can contribute to the accomplishment of improved contrast and brightness in display devices and higher levels of energy conversion effi ciency in solar panels. Traditional ARCs improve optical transmittance by introducing destructive interference between refl ected light beams from the air-fi lm and fi lm-substrate interfaces. An ideal ARC should satisfy the requirements of a quarter-wavelength fi lm thickness and a fi lm η of ( η s ) 0.5 , where η s denotes the η of the substrate. [ 1 ] However, an ARC with a homogeneous η can achieve high transmittance only in narrow wavelength and incidence angle ranges, which are fi xed by its thickness and refractive index. In contrast, an ARC with a gradually changing η , also known as a graded index, can avoid the formation of an interface with a sharp contrast in η . As a result, the Fresnel refl ection can be effectively minimized in a wide wavelength range and high optical transparency can be achieved. In an ideal gradedindex anti-refl ection coating (GIARC), the η should gradually vary from that of the substrate material, onto which the GIARC is coated, to the η of air ( ∼ 1), necessitating the use of a material with a widely tunable η . Theoretical studies showed that a quintic profi le of η varying from that of the substrate (typically 1.5‐2) to 1 is best for achieving the lowest refl ectance (<0.1% in the visible range). [ 2 ] While dense materials generally have an η larger than ∼ 1.35, the extensive variability of indices has been demonstrated by nanoporous materials for the applications for GIARC. [ 2‐6 ] Various methods, such as lithography, obliqueangle deposition, catalytic etching, chemical vapor deposition, and a sol-gel process, have been reported. [ 2‐5 ] However, these methods may lack cost-effectiveness and high-throughput capabilities due to the requirements of vacuum processing, multiple etching steps, or because of the limited controllability of η . Recently, highly porous block copolymer (BCP) thin fi lms were applied to the fabrication of ARC due to the excellent low-cost solution processability and facile tunability of η when controlling the fraction of the pores generated by the selective removal of one block. [ 7‐11 ] Kim and co-workers reported a wide tuning range of η between 1.17 and 1.42 in nanoporous polystyrene (PS) thin fi lms obtained by removing poly(methyl methacrylate) (PMMA) in PS-PMMA BCPs. The stacking of three PS layers with gradually changing porosity achieved a minimum refl ectance of less than 0.1%. Han and coworkers demonstrated that a mixture of PS-PMMA BCPs and PMMA homopolymers led to a graded distribution of PMMA along the vertical direction of the thin fi lms and that a gradient η can be obtained for the remaining PS nanostructures after the removal of PMMA, which can reduce the number of processing steps including spin-coating and acid etching. However, these approaches may be associated with challenges related to the low chemical and mechanical stability of the porous organic thin fi lms and the

Hierarchical scaffolds via combined macro- and micro-phase separation

Recent advances in biomaterial surface engineering have shown that surface biomechanical, spatial and topographical properties can elicit control over fundamental biological processes such as cell shape, proliferation, differentiation and apoptosis. Along these lines, we have very recently shown that the self-assembly of block copolymers into thin films can be used as an extremely labile method to precisely position cellular adhesion molecules, at nanometre lateral spacings, to effect control over cell attachment and morphology. Here, we extend our work in 2-dimensional block copolymer films into the production of 3-dimensional porous block copolymer scaffolds. The reported method combines macro-scale temperature induced phase separation and micro-phase separation of block copolymers to produce highly porous scaffolds with surfaces comprised of nano-scale self-assembled block copolymer domains, representing a significant advance in currently available scaffold engineering technologies. The phase behaviour of these polymer–solvent systems is described and potential mechanisms leading to the observed structure formation are presented. The nano-domains have thereafter been functionalised with CGRGDS peptides throughout the scaffold and shown to effect changes in cell attachment and spreading, in agreement with previous 2-dimensional studies. These multi-scale, functional scaffolds are easy to manufacture and scaleable, making them ideal candidates for tissue engineering applications.