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Solar cell coloration with minimum optical loss is increasingly required for building‐integrated photovoltaics (BIPV) in modern urban areas because of its importance in harmonizing the exterior of zero‐energy buildings and surroundings. A simple strategy for developing a distributed Bragg reflector (DBR) is designated with 1D lamella‐forming polystyrene‐b‐poly(2‐vinylpyridine) (PS‐b‐P2VP) films. An optimized thermal annealing process produces defect‐free lamellar microdomains oriented parallel to the substrate throughout the film. The selective crosslinking in the P2VP block and swelling of these films in a methanol solution with methanesulfonic acid facilitate the formation of highly asymmetric gigantic lamellae, enabling the entire visible‐wavelength spectrum of DBR structural colors. Three representative red (R), green (G), and blue (B) DBR films are produced on a Si solar cell. Coloration from high‐reflectance and narrow‐width DBR films results in vividly colored Si solar cells with a minor or negligible reduction in power conversion efficiency. The approach for photovoltaics, in terms of both the attractive esthetic and technical aspects of BIPV application, offers a viable method for fabricating high‐performance DBR films based on block copolymer self‐assembly. [ABSTRACT FROM AUTHOR]

Pressure‐sensitive‐adhesives (PSAs) are pervasive in electronic, automobile, packaging, and biomedical applications due to their ability to stick to numerous surfaces without undergoing chemical reactions. These materials are typically synthesized by the free radical copolymerization of alkyl acrylates and acrylic acid, leading to an ensemble of polymer chains with varying composition and molecular weight. Here, reversible addition−fragmentation chain‐transfer (RAFT) copolymerizations in a semi‐batch reactor are used to tailor the molecular architecture and bulk mechanical properties of acrylic copolymers. In the absence of cross‐links, the localization of acrylic acid toward the chain ends leads to microphase separation, creep resistance, and enhanced tack. However, in the presence of Al(acac)3 crosslinker, the creep resistance remains unchanged and mostly the large‐strain mechanical properties are affected. This behavior is attributed to microphase separation, but also to a change in the energy required to break physical associations, and untangle and elongate associative polymers to large deformations. [ABSTRACT FROM AUTHOR]

Here, we observed, via small-angle X-ray scattering and transmission electron microscopy, co-existing morphologies of lamellae and cylinders by precisely tailoring the volume fraction of each block in polystyrene-b-polyisoprene-b-polystyrene-b-poly(2-vinylpyridine) tetrablock terpolymer (S1IS2V). The PI cylinders are located inside the PS microdomains. This is due to the presence of the mid-block PS2 which effectively isolates PI cylinders from the interface between PS and P2VP lamellae. The experimentally observed morphology is in good agreement with the predicted phase by self-consistent field theory. Furthermore, we successfully adjusted the position of the PI cylinders inside the PS lamellar microdomains by changing the length of the PS2 mid-block. Finally, we obtained vertically oriented lamellae and cylinders in S1IS2V films with the aid of solvent annealing.

RAFT aqueous emulsion polymerization of isopropylideneglycerol monomethacrylate (IPGMA) is used to prepare a series of PGEO5MA46‐PIPGMAy nanoparticles, where PGEO5MA is a hydrophilic methacrylic steric stabilizer block bearing pendent cis‐diol groups. TEM studies confirm a spherical morphology while dynamic light scattering (DLS) analysis indicated that the z‐average particle diameter can be adjusted by varying the target degree of polymerization for the core‐forming PIPGMA block. Periodate oxidation is used to convert the cis‐diol groups on PGEO5MA46‐PIPGMA500 and PGEO5MA46‐PIPGMA1000 nanoparticles into the analogous aldehyde‐functionalized nanoparticles, which are then reacted with histidine via reductive amination. In each case, the extent of functionalization is more than 99% as determined by 1H NMR spectroscopy. Aqueous electrophoresis studies indicate that such derivatization converts initially neutral nanoparticles into zwitterionic nanoparticles with an isoelectric point at pH 7. DLS studies confirm that such histidine‐derivatized nanoparticles remain colloidally stable over a wide pH range. A quartz crystal microbalance is employed at 25°C to assess the adsorption of both the cis‐diol‐ and histidine‐functionalized nanoparticles onto planar stainless steel at pH 6. The histidine‐bearing nanoparticles adsorb much more strongly than their cis‐diol counterparts. For the highest adsorbed amount of 70.5 mg m–2, SEM indicates a fractional surface coverage of 0.23 for the adsorbed nanoparticles. [ABSTRACT FROM AUTHOR]

Hierarchical cylindrical nanostructures with different diameters (or shapes) have received much attention because of potential applications to next‐generation lithography or advanced optical devices. Herein, via small‐angle X‐ray scattering and transmission electron microscopy, tetragonally and rectangularly packed hierachical cylindrical nanostructures are observed by tailoring the volume fraction of polystyrene mid‐block in polystyrene‐b‐polyisoprene‐b‐polystyrene‐b‐poly(2‐vinylpyridine) tetrablock terpolymer (S1IS2V). P2VP becomes the main cylinder, while PI forms satellite cylinders surrounding the main P2VP cylinder. When the length of S2 block is relatively short, tetragonal arrangement of cylinders is observed. But, a rectangular arrangement of cylinders is formed for larger S2 block. The experimentally observed hierarchical cylindrical nanostructures are in good agreement with the prediction by the self‐consistent field theory. [ABSTRACT FROM AUTHOR]

This Feature Article focuses on the rational design of 'shape-shifting' thermoresponsive diblock copolymer nano-objects prepared using 2‑hydroxypropyl methacrylate, 4‑hydroxybutyl acrylate or hydroxybutyl methacrylate. A subtle change in the partial degree of hydration of the permanently insoluble thermoresponsive block drives thermal transitions between spheres, worms, vesicles and lamellae. Potential applications for this fascinating new class of amphiphiles are suggested. [Display omitted] In this Feature Article , we review our recent progress in the design of shape-shifting thermoresponsive diblock copolymer nano-objects, which are prepared using various hydroxyl-functional (meth)acrylic monomers (e.g. 2‑hydroxypropyl methacrylate, 4‑hydroxybutyl acrylate or hydroxybutyl methacrylate) to generate the thermoresponsive block. Unlike traditional thermoresponsive polymers such as poly(N -isopropylacrylamide), there is no transition between soluble and insoluble polymer chains in aqueous solution. Instead, thermally driven transitions between a series of copolymer morphologies (e.g. spheres, worms, vesicles or lamellae) occur on adjusting the aqueous solution temperature owing to a subtle change in the partial degree of hydration of the permanently insoluble thermoresponsive block. Such remarkable self-assembly behavior is unprecedented in colloid science: no other amphiphilic diblock copolymer or surfactant system undergoes such behavior at a fixed chemical composition and concentration. Such shape-shifting nano-objects are characterized by transmission electron microscopy, dynamic light scattering, small-angle X-ray scattering, rheology and variable temperature 1H NMR spectroscopy. Potential applications for this fascinating new class of amphiphiles are briefly considered. [ABSTRACT FROM AUTHOR]

Increasingly intricate in their multilevel multiscale microarchitecture, metamaterials with unique physical properties are challenging the inherent constraints of natural materials. Their applicability in the nanomedicine field still suffers because nanomedicine requires a maximum size of tens to hundreds of nanometers; however, this size scale has not been achieved in metamaterials. Therefore, "nano‐metamaterials," a novel class of metamaterials, are introduced, which are rationally designed materials with multilevel microarchitectures and both characteristic sizes and whole sizes at the nanoscale, investing in themselves remarkably unique and significantly enhanced material properties as compared with conventional nanomaterials. Microarchitectural regulation through conventional thermodynamic strategy is limited since the thermodynamic process relies on the frequency‐dependent effective temperature, Teff(ω), which limits the architectural regulation freedom degree. Here, a novel dual‐kinetic control strategy is designed to fabricate nano‐metamaterials by freezing a high‐free energy state in a Teff(ω)‐constant system, where two independent dynamic processes, non‐solvent induced block copolymer (BCP) self‐assembly and osmotically driven self‐emulsification, are regulated simultaneously. Fe3+‐"onion‐like core@porous corona" (Fe3+‐OCPCs) nanoparticles (the products) have not only architectural complexity, porous corona and an onion‐like core but also compositional complexity, Fe3+ chelating BCP assemblies. Furthermore, by using Fe3+‐OCPCs as a model material, a microstructure‐biological performance relationship is manifested in nano‐metamaterials. [ABSTRACT FROM AUTHOR]

Abstract Increasingly intricate in their multilevel multiscale microarchitecture, metamaterials with unique physical properties are challenging the inherent constraints of natural materials. Their applicability in the nanomedicine field still suffers because nanomedicine requires a maximum size of tens to hundreds of nanometers; however, this size scale has not been achieved in metamaterials. Therefore, “nano‐metamaterials,” a novel class of metamaterials, are introduced, which are rationally designed materials with multilevel microarchitectures and both characteristic sizes and whole sizes at the nanoscale, investing in themselves remarkably unique and significantly enhanced material properties as compared with conventional nanomaterials. Microarchitectural regulation through conventional thermodynamic strategy is limited since the thermodynamic process relies on the frequency‐dependent effective temperature, Teff(ω), which limits the architectural regulation freedom degree. Here, a novel dual‐kinetic control strategy is designed to fabricate nano‐metamaterials by freezing a high‐free energy state in a Teff(ω)‐constant system, where two independent dynamic processes, non‐solvent induced block copolymer (BCP) self‐assembly and osmotically driven self‐emulsification, are regulated simultaneously. Fe3+‐“onion‐like core@porous corona” (Fe3+‐OCPCs) nanoparticles (the products) have not only architectural complexity, porous corona and an onion‐like core but also compositional complexity, Fe3+ chelating BCP assemblies. Furthermore, by using Fe3+‐OCPCs as a model material, a microstructure‐biological performance relationship is manifested in nano‐metamaterials.

Block copolymer (BCP) self‐assembly‐assisted doping for semiconductors is used to achieve discrete doping with nanometer‐scale junction depth, high throughput, and large area coverage. As devices become smaller and more sophisticated, spatial control of dopants becomes more critical. A variety of doping methods, such as monolayer doping and δ‐doping, have been developed to replace the conventional doping method, ion‐implantation; however, lateral patterning of dopants relies on photo‐ or e‐beam lithography. To address these challenges, a self‐assembling dopant (boron)‐containing BCP is designed to directly pattern dopants on the nanometer scale. This method skips the lithography step and is compatible with directed self‐assembly approaches. The effect of the boron concentration in the BCP on the doping performance is systematically studied by changing the volume fraction of the boron‐containing block while keeping the domain spacing and the mesoscale morphology constant. Successful self‐assembly of the BCP into a hexagonally packed cylindrical morphology is confirmed by small‐angle X‐ray scattering and resonant soft X‐ray scattering with a 26 nm cylinder‐to‐cylinder distance. Doping silicon using these BCPs enables discrete doped areas with shallow (7–13 nm) junction depth as demonstrated by the depth profile of boron, and supported by a sheet resistance study. [ABSTRACT FROM AUTHOR]

Block copolymers are recognized as a valuable platform for creating nanostructured materials. Morphologies formed by block copolymer self-assembly can be transferred into a wide range of inorganic materials, enabling applications including energy storage and metamaterials. However, imaging of the underlying, often complex, nanostructures in large volumes has remained a challenge, limiting progress in materials development. Taking advantage of recent advances in X-ray nanotomography, we noninvasively imaged exceptionally large volumes of nanostructured hybrid materials at high resolution, revealing a single-diamond morphology in a triblock terpolymer-gold composite network. This morphology, which is ubiquitous in nature, has so far remained elusive in block copolymer-derived materials, despite its potential to create materials with large photonic bandgaps. The discovery was made possible by the precise analysis of distortions in a large volume of the self-assembled diamond network, which are difficult to unambiguously assess using traditional characterization tools. We anticipate that high-resolution X-ray nanotomography, which allows imaging of much larger sample volumes than electron-based tomography, will become a powerful tool for the quantitative analysis of complex nanostructures and that structures such as the triblock terpolymer-directed single diamond will enable the generation of advanced multicomponent composites with hitherto unknown property profiles.

Synthesis of polymeric nanoparticles of controlled non-spherical morphology is of profound interest for a wide variety of potential applications. Self-assembly of amphiphilic diblock copolymers is an attractive bottom-up approach to prepare such nanoparticles. In the present work, RAFT polymerization is employed to synthesize a variety of poly(N,N-dimethylacrylamide)-b-poly[butyl acrylate-stat-GCB] copolymers, where GCB represents vinyl monomer containing triazine based Janus guanine-cytosine nucleobase motifs featuring multiple hydrogen bonding arrays. Hydrogen bonding between the hydrophobic blocks exert significant influence on the morphology of the resulting nanoparticles self-assembled in water. The Janus feature of the GCB moieties makes it possible to use a single polymer type in self-assembly, unlike previous work exploiting, e.g., thymine-containing polymer and adenine-containing polymer. Moreover, the strength of the hydrogen bonding interactions enables use of a low molar fraction of GCB units, thereby rendering it possible to use the present approach for copolymers based on common vinyl monomers for the development of advanced nanomaterials., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Utilizing the self-assembly of block copolymers with large Flory-Huggins interaction parameters (χ) for nanofabrication is a formidable challenge due to the attendant large surface energy differences between the blocks. This work reports a robust protocol for the fabrication of thin films with highly ordered cylindrical nanopore arrays via the self-assembly of an asymmetric poly(styrene- block -4-vinylpyridine) (PS- b -P4VP) diblock copolymer blended with a P4VP homopolymer. The desired vertical domain orientation is achieved at the air-polymer interface by controlled solvent vapor annealing (SVA) using acetone, a solvent with weak selectivity for PS over P4VP, and at the substrate interface by functionalization using a hydroxy-terminated poly(2-vinylpyridine) (P2VP-OH) homopolymer brush. In contrast, the vertical cylinder orientation is unstable during acetone SVA on substrates functionalized using hydroxy-terminated poly(methyl methacrylate) (PMMA-OH). Although PMMA exhibits more balanced interfacial energies between PS and P4VP than P2VP in the dry state, it is also swollen more selectively by acetone. We hypothesize that the nearly balanced solvent swelling of the three polymers (P2VP, P4VP, and PS) stabilizes the vertical cylinder orientation, while unbalanced swelling (PMMA > P4VP and PS) does not. We further characterize pore formation by addition of a P4VP homopolymer and its postassembly extraction using ethanol, revealing a narrow window of pore size tunability. Notably, minimal differences in nanopore morphologies are observed for P4VP volume fractions as high as 0.1, regardless of the P4VP molar mass. However, further increasing the P4VP volume fraction results in domain reorientation or macrophase separation when its molar mass is less than or greater than the P4VP block molar mass, respectively. Using a P4VP homopolymer that is nearly equal in length to the P4VP block enables the fabrication of well-ordered arrays of vertical, through-film nanopores with high aspect ratios (>10), small periods (<23 nm), and diameters less than 10 nm.

Surface segregation in blended polymer films has attracted much interest in fundamental research as well as for practical applications. A variety of methodologies have been proposed for controlling surface segregation. They often require long annealing times, however, to achieve thermodynamic equilibrium. Here, a strategy and proof‐of‐principle experiments are described to control surface segregation of thin block‐copolymer (BCP) layers on top of a homopolymer in a single casting step from blended BCP/homopolymer solutions. The surface coverage by the minor constituent BCP (2–10 wt%) is accomplished despite almost identical surface energies of BCP and homopolymer constituents. Immersing this casted solution into water for nonsolvent induced phase separation (NIPS), a nonequilibrium process, affords solidified bilayer ultrafiltration membranes composed of a thin porous surface layer of self‐assembled BCP atop an asymmetric porous homopolymer substructure. Key to successful BCP surface segregation is the choice of a binary solvent system based on careful considerations of solvent surface energies and polymer‐solvent interaction parameters. Furthermore, stabilizing the BCP micellar structure by a divalent metal additive is also essential. The approach provides a cost‐effective method for fabricating bilayer‐type asymmetric ultrafiltration membranes with uniform BCP self‐assembly based selective top surface pore layers in a single casting step. [ABSTRACT FROM AUTHOR]

The development and study of a benchtop, high-throughput, and inexpensive fabrication strategy to obtain hierarchical patterns of biomolecules with sub-50 nm resolution is presented. A diblock copolymer of polystyrene-b-poly(ethylene oxide), PS-b-PEO, is synthesized with biotin capping the PEO block and 4-bromostyrene copolymerized within the polystyrene block at 5 wt %. These two handles allow thin films of the block copolymer to be postfunctionalized with biotinylated biomolecules of interest and to obtain micropatterns of nanoscale-ordered films via photolithography. The design of this single polymer further allows access to two distinct superficial nanopatterns (lines and dots), where the PEO cylinders are oriented parallel or perpendicular to the substrate. Moreover, we present a strategy to obtain hierarchical mixed morphologies: a thin-film coating of cylinders both parallel and perpendicular to the substrate can be obtained by tuning the solvent annealing and irradiation conditions.

The formation of various bicontinuous phases from binary blends of linear AB diblock copolymers (DBCPs) is studied using the polymeric self‐consistent field theory. The theoretical study predicts that the double diamond and the "plumber's nightmare" phases, which are metastable for neat DBCPs, could be stabilized in block copolymers with designed dispersity, namely, binary blends composed of a gyroid‐forming DBCP and a homopolymer‐like DBCP. The spatial distribution of different monomers reveals that these two types of DBCPs are segregated such that the homopolymer‐like component is localized at the nodes to relieve the packing frustration. Simultaneously, the presence of a local segregation of the two DBCPs on the AB interface regulates the interfacial curvature. These two mechanisms could act in tandem for homopolymer‐like DBCPs with proper compositions, resulting in larger stable regions for the novel bicontinuous phases. [ABSTRACT FROM AUTHOR]

Diblock copolymer nanoparticles prepared in non-polar solvents that are sterically stabilized but possess ionic functionality from the inclusion of cationic comonomers in the stabilizer shell are known to exhibit complex electrokinetic behavior (Chem. Sci. 9 (2018) 922–934). For example, core-shell nanoparticles with cationic comonomers located solely within the shell layer have lower magnitude electrophoretic mobilities than nanoparticles containing the same cationic comonomers located within the core, whereas nanoparticles prepared using a minor fraction of steric stabilizer chains containing cationic comonomer repeat units have comparable electrophoretic mobilities to nanoparticles prepared with this cationic comonomer solely located within the core. We hypothesize that these observations can be explained in terms of the strength of the Coulombic interaction between counterions and the nanoparticle interface. The highly-fluorinated anionic counterion associated with these cationic nanoparticles is studied by 19 F nuclear magnetic resonance (NMR) spectroscopy in n -dodecane. This revealed only one type of 19 F environment for a soluble macromolecular cation (the oil-soluble steric stabilizer chains used to prepare the nanoparticles), whereas two distinct environments were observed for the sterically-stabilized cationic nanoparticles. Both 19 F diffusion NMR and 19 F– 13 C heteronuclear single quantum correlation (HSQC) measurements support the existence of two environments for this counterion. The existence of two distinct 19 F environments for the highly-fluorinated anion associated with the sterically-stabilized nanoparticles demonstrates the presence of spectroscopically distinguishable populations of ion pairs and of fully dissociated free anions. 19 F NMR spectra recorded for sterically-stabilized nanoparticles with a fully ionic shell (all stabilizer chains containing the cationic comonomer) and those with a partly ionic shell (10% of stabilizer chains containing the cationic comonomer) reveal a higher proportion of dissociated anions in the partly ionic case. This suggests a stronger Coulombic interaction between counterions and the cationic interface when the shell is fully ionic, which accounts for the observed reduction in the magnitude of the electrophoretic mobility. [ABSTRACT FROM AUTHOR]

Block copolymers (BCPs) are particularly effective in creating soft nanostructured templates for transferring complex 3D network structures into inorganic materials that are difficult to fabricate by other methods. However, achieving control of the local ordering within these 3D networks over large areas remains a significant obstacle to advancing material properties. Here, we address this challenge by directing the self-assembly of a 3D alternating diamond morphology by solvent vapor annealing of a triblock terpolymer film on a chemically patterned substrate. The hexagonal substrate patterns were designed to match a (111) plane of the diamond lattice. Commensurability between the sparse substrate pattern and the BCP lattice produced a uniformly ordered diamond network within the polymer film, as confirmed by a combination of atomic force microscopy and cross-sectional imaging using focused ion beam scanning electron microscopy. The successful replication of the complex and well-ordered 3D network structure in gold promises to advance optical metamaterials and has potential applications in nanophotonics.

Fabrication of porous membranes with high permeability and selectivity together has attracted great attention due to their potential applications in various fields including sensing, catalysis, filtration, separation, drug delivery, etc. In this work, very simple yet highly efficient method to generate mesoporous composite membranes with straight pores at the top has been reported via block copolymer self-assembly combined with polysulfone microporous membrane. The composite membranes are composed of the active layer of block copolymers with straight nanopores and the supporting layer of polysulfone membrane giving the mechanical stability. The top layer via block copolymer self-assembly exhibits the well-ordered, vertically-oriented cylindrical structures through direct spin-coating on the supporting membrane without additional process. The final structure is ideal for water filtration, ultimately providing high flux as well as selectivity due to high density and small size of nanopores in BCP layer. The surface interaction of block components has been proven to be key parameter in determining the structure and orientation. In addition, here, the application as a separation membrane due to the size exclusion have been successfully demonstrated. [ABSTRACT FROM AUTHOR]

Block copolymers (BCPs) have stimulated widespread research interest due to their applications as facile templates in the fabrication of optimized thermosets with micro- or nanostructured morphologies. In the present work, a novel block copolymer was obtained from a commercial poly(styrene-block-butadiene-block-styrene) (SBS) triblock copolymer precursor by a two-step process including reaction with hydrogen peroxide in a water/dichloroethane biphasic system to achieve an epoxidized derivative with a 46 mol% degree of epoxidation (thus denoted as eSBS46), which was then followed by reaction with 1-(2-aminoethyl)piperazine (AEP, thus yielding eSBS46-AEP) as a reactive functional group that was incorporated to prepare nanostructured epoxy thermosetting blends. As a result of the oxirane ring-opening achieved (to a conversion degree of 10 mol%) by reaction with AEP, the nanostructured morphology was converted from spherical micelles in the case of eSBS46 to branched wormlike micelles for eSBS46-AEP. At 5 wt% loading of this BCP material, the fracture toughness was improved by 51% over the neat epoxy. These findings were compared with data obtained from the same epoxy thermoset formulation containing the eSBS46. Various measurements including transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and measuring stress field factor (KIC) analysis were employed to investigate the morphology, fracture graph, storage modulus, glass transition temperature (Tg), and fracture toughness of the epoxy thermosets containing these BCPs. The specific side-groups of eSBS46-AEP containing secondary amines and ternary amines increased the reactivity to epoxy matrices. A combination of fracture mechanisms including shear deformation, crack tip blunting, and matrix ductility enhancement contributed toward helped enhance the toughness. These results demonstrate that the role of modulating the reactivity of BCP has a significant effect on the final morphology and properties of the epoxy composites. [ABSTRACT FROM AUTHOR]

ABSTRACT: We report an approach to control the pore characteristics of hierarchically porous polymers (HPPs) containing micropores in a well‐defined 3D continuous mesoporous framework, by the hyper‐crosslinking reaction of a crosslinked block polymer precursor polylactide‐b‐poly(vinylbenzyl chloride‐co‐styrene‐co‐divinylbenzene) (PLA‐b‐P(VBzCl‐co‐S‐co‐DVB)) consisting of bicontinuous PLA and P(VBzCl‐co‐S‐co‐DVB) microdomains. We investigated the hyper‐crosslinking reaction of P(VBzCl‐co‐S‐co‐DVB)s synthesized by reversible addition‐fragmentation chain transfer (RAFT) copolymerization, and then examined the effect of VBzCl, S, DVB, and polylactide macrochain transfer agent (PLA‐CTA) contents in the polymerization mixture on the pore characteristics of the HPPs. We demonstrate that while the VBzCl content responsible for the hyper‐crosslinking reaction primarily governs microporosity, the DVB content has a strong influence on the mesopore structure, as it determines the onset of the gelation of the polymerization mixture, which arrests the emerging disordered bicontinuous morphology induced by the polymerization‐induced microphase separation process. Because the PLA microdomains template the percolating mesoporous space, mesoporosity was mainly controlled by the PLA‐CTA contents. The synergistic combination of hyper‐crosslinking and block polymer self‐assembly in the HPP formation provided a highly reinforced mesoporous framework, stable against pore collapse, and interconnected mesopores. These facilitated diffusion to the microporous surfaces, suggesting its utility for advanced absorbents and catalytic supports. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 900–913 [ABSTRACT FROM AUTHOR]

Fouling is a critical issue in membrane process operation as it greatly compromises the efficiency of the treatment processes. A promising approach to overcome this problem is the production of easy-to-clean membranes by incorporating stimuli-responsive pores. In this study, we fabricated thermo-responsive polystyrene- b -poly( N -isopropyl acrylamide) (PS- b -PNIPAM) block copolymer membranes using the self-assembly and non-solvent induced phase separation (SNIPS) method and systematically varied several membrane casting parameters, i.e. evaporation time, polymer concentration, solvent type and water content, to obtain nano- and isoporous membranes. Membranes with a disordered surface were obtained for PS selective solvents, whereas isoporous membranes were obtained when the block copolymers were dissolved in PNIPAM selective solvent mixtures. Using 1,4-dioxane/ tetrahydrofuran mixtures resulted in isoporous membranes for a large parameter space, indicating the robustness of structure formation in the PS- b -PNIPAM system. Permeability tests at various temperatures demonstrated fully reversible thermo-responsive behavior of the membranes. [ABSTRACT FROM AUTHOR]

Polyion complex vesicles (PICsomes) are characterized by their unique three-layered semipermeable nanomembrane structures, in which a unilamellar PIC layer is sandwiched by poly(ethylene glycol) layers, and have gathered much attention as nano-scaled drug vehicles. Herein, the crosslinking degree of the nanomembrane in the PICsome was controlled systematically for the first time. Permeability of the PICsome nanomembrane was evaluated through a kinetic study of the release of macromolecular cargoes from the PICsome. The degree of crosslinking in the nanomembrane successfully regulated the release behavior. Moreover, the shape and size of the macromolecular solutes were found to be critical factors determining their transport from the inner aqueous phase of the PICsome to the external environment. The results indicate that the unique three-layered structure of PICsome membranes plays a key role in modulating solute transport. These findings will provide a rational strategy for the development of nanomembrane-based controlled-release systems. [ABSTRACT FROM AUTHOR]

The self-assembly of block copolymers in aqueous solution is an important field in modern polymer science that has been extended to double hydrophilic block copolymers (DHBC) in recent years. In here, a significant improvement of the self-assembly process of DHBC in aqueous solution by utilizing a linear-brush macromolecular architecture is presented. The improved self-assembly behavior of poly(N-vinylpyrrolidone)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (PVP-b-P(OEGMA)) and its concentration dependency is investigated via dynamic light scattering (DLS) (apparent hydrodynamic radii ≈ 100−120 nm). Moreover, the DHBC assemblies can be non-covalently crosslinked with tannic acid via hydrogen bonding, which leads to the formation of small aggregates as well (apparent hydrodynamic radius ≈ 15 nm). Non-covalent crosslinking improves the self-assembly and stabilizes the aggregates upon dilution, reducing the concentration dependency of aggregate self-assembly. Additionally, the non-covalent aggregates can be disassembled in basic media. The presence of aggregates was studied via cryogenic scanning electron microscopy (cryo-SEM) and DLS before and after non-covalent crosslinking. Furthermore, analytical ultracentrifugation of the formed aggregate structures was performed, clearly showing the existence of polymer assemblies, particularly after non-covalent crosslinking. In summary, we report on the completely hydrophilic self-assembled structures in solution formed from fully biocompatible building entities in water.

Block copolymer (BCP) thin films are interesting material systems for nanofabrication since they can form well-defined periodic nanostructures by microphase separation. However, attaining a specific morphology with the required orientation can be challenging. In this study, we investigated the morphological behavior of polystyrene- b -poly( N -isopropylacrylamide)- b -polystyrene (PS- b -PNIPAM- b -PS) BCP thin films by using Atomic Force Microscopy (AFM) and in-situ Grazing-Incidence X-ray Scattering (GISAXS) during selective solvent annealing. Thin films of a lamellar BCP were annealed by using various solvents with different selectivity for the blocks, such as PNIPAM-selective methanol, non-selective tetrahydrofuran (THF) and PS-selective toluene. Solvent annealing using methanol: THF 1:2 (v:v) or methanol: toluene 1:1 (v:v) resulted in the formation of hexagonally ordered perpendicular cylinders, whereas no sustained long-range order was found when only one type of solvent was used. PS- b -PNIPAM- b -PS BCP thin films that have hexagonally ordered perpendicular cylinders are promising for applications where thermo-responsiveness is desired, such as nanofiltration and biomedical applications. [ABSTRACT FROM AUTHOR]

We demonstrate that the temperature-dependent phase behaviors of parallel and perpendicular cylinder-forming block copolymers are governed by domain-domain segregation forces inherently present in block copolymer material itself. With increasing temperature, a parallel cylinder-forming block copolymer experienced a parallel cylinder straightening process before the order-disorder transition (ODT) and did not show long-range composition fluctuations near the ODT temperature due to the weak segregation forces between the block domains. A perpendicular cylinder-forming block copolymer with a strong segregation force between the block domains displayed cylinder orientation transition from perpendicular to parallel below the ODT temperature. On the other hand, a perpendicular cylinder-forming block copolymer material with an exceptionally strong segregation force between the block domains maintained its initial perpendicular cylinder orientation up to near the ODT temperature. In both cases of perpendicular cylinder-forming block copolymers, submicrometer-scale long-range composition fluctuations were observed well above the ODT temperature due to their intrinsically strong segregation forces between the block domains.

Linear poly(4- tert-butoxystyrene)- b-poly(4-vinylpyridine) (P tBOS- b-P4VP) diblock copolymers are synthesized using reversible addition-fragmentation chain transfer polymerization. The self-assembly of four different P tBOS- b-P4VP diblock copolymers is studied using small-angle X-ray scattering and transmission electron microscopy and a number of interesting observations are made. A tBOS62- b-4VP28 diblock copolymer with a weight fraction P4VP of 0.21 shows a disordered morphology of P4VP spheres with liquid-like short-range order despite an estimated value of [ABSTRACT FROM AUTHOR]

Abstract: The self-assembly of an amphiphilic pentablock terpolymer, consisting of a pH-sensitive poly(2-vinylpyridine) (P2VP) central block, bearing at both ends hydrophilic poly(ethylene oxide) (PEO) end-capped with hydrophobic poly(ε-caprolactone) (PCL) blocks was investigated in aqueous media. When the polymer was transferred to aqueous medium through solvent exchange technique, micellar assemblies were obtained, with a morphological switch from “flower-like” crew-cut micelles to large compound vesicles upon partial quaternization of 2VP block. More importantly, well-defined polymer vesicles were formed when thin film hydration method was employed. Such polymersomes presented “flower-like” morphology, with a membrane composed of self-assembled P2VP hydrophobic central blocks shielded by PCL hydrophobic ends and surrounded by PEO looping chains at the inner and outer surfaces. The potential of the pentablock vesicles as drug delivery carriers was explored by encapsulation of calcein, a model hydrophilic drug, in the polymersomes and monitoring its release at different pH values simulating physiological environments. It is shown that the release profile of the nanoparticle formulations could be modulated by tuning the membrane permeability either through chemical (i.e. partial quaternization) and/or physical (i.e. pH variations) pathways. [Copyright &y& Elsevier]

Treatment of a Ni-terminated poly(3-hexylthiophene) (P3HT), generated in situ from 5-chloromagnesio-2-bromo-3-hexylthiophene and Ni(1,3-bis(diphenylphosphino)propane)Cl2, with a perylene diimide-functionalized arylisocyanide monomer effects a chain-extension polymerization to afford a donor-acceptor diblock copolymer using a single catalyst and in a single reaction vessel. The two mechanistically distinct polymerizations proceed in a controlled, chain growth fashion, allowing the molecular weight of both the P3HT and poly(isocyanide) blocks to be tuned by adjusting the initial monomer-to-catalyst ratios. The resulting materials are found to self-assemble into crystalline, lamellar stacks of donor and acceptor components in the solid state, and also exhibit fluorescence quenching in thin films, properties which poise these materials for use in organic photovoltaic applications. [ABSTRACT FROM AUTHOR]

The widespread realization of wearable electronics requires printable active materials capable of operating at low voltages. Polymerized ionic liquid (PIL) block copolymers exhibit a thickness-independent double-layer capacitance that makes them a promising gating medium for the development of organic thin-film transistors (OTFTs) with low operating voltages and high switching speed. PIL block copolymer structure and self-assembly can influence ion conductivity and the resulting OTFT performance. In an OTFT, self-assembly of the PIL gate on the semiconducting polymer may differ from bulk self-assembly, which would directly influence electrical double-layer formation. To this end, we used poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt -5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) as a model semiconductor for our OTFTs, on which our PILs exhibited self-assembly. In this study, we explore this critical interface by grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscopy (AFM) of P(NDI2OD-T2) and a series of poly(styrene)- b -poly(1-(4-vinylbenzyl)-3-butylimidazolium-random-poly(ethylene glycol) methyl ether methacrylate) (poly(S)- b -poly(VBBI + [X]-r-PEGMA)) block copolymers with varying PEGMA/VBBI + ratios and three different mobile anions (where X = TFSI - , PF 6 - , or BF 4 - ). We investigate the thin-film self-assembly of block copolymers as a function of device performance. Overall, a mixed orientation at the interface leads to improved device performance, while predominantly hexagonal packing leads to nonfunctional devices, regardless of the anion present. These PIL gated OTFTs were characterized with a threshold voltage below 1 V, making understanding of their structure-property relationships crucial to enabling the further development of high-performance gating materials.

An insightful perspective toward the design and fabrication of new phase segregated block copolymers–perovskite quantum dots composite through Lewis acid-base adduct for a wide range of wearable electronics application. [Display omitted] • Understanding of the thermodynamic contribution of nanoparticle additive. • Investigation of the Lewis acid-base block copolymer-bulk perovskite composite. • Effect of Lewis adduct and thermodynamic for perovskite quantum dots additive. • Versatile block copolymer-perovskite quantum dots self-assembled composite approach. • BCP-PQDs composite-based optoelectronic conceptualization and exploration. In-depth understanding of block copolymer (BCP) thermodynamics allows to obtain numerous self-assembled nanostructures and further extend the BCP capabilities to host additives. Therefore, different research groups have begun incorporating additives of versatile nature such as nanoparticles or electrolytes. Within BCP composite systems, additives alter the original BCP self-assembled structure in which host–guest interaction must be further investigated. Recently, perovskite revealed to be a promising optoelectronic material but its applications have been limited due to insufficient long-term stability. Polymeric Lewis base interaction with perovskite precursor has emerged as a strong approach to obtain highly stable perovskite. To address the potential application and versatility of perovskite materials, this review summarizes recent advances and highlights a new potentially sustainable approach to BCP encapsulation of perovskite quantum dots (PQDs) through Lewis acid-base interaction. The conceptual composite aims to drastically enhance perovskite stability through controlled chemical and thermodynamic interaction between the BCP and PQDs. This review highlights major key points to understand and address for the design and fabrication of original BCP-PQDs composite with remarkable versatility, stability and high performances in presented optoelectronic applications. [ABSTRACT FROM AUTHOR]

We demonstrate that the temperature-dependent phase behaviors of parallel and perpendicular cylinder-forming block copolymers are governed by domain-domain segregation forces inherently present in block copolymer material itself. With increasing temperature, a parallel cylinder-forming block copolymer experienced a parallel cylinder straightening process before the order-disorder transition (ODT) and did not show longrange composition fluctuations near the ODT temperature due to the weak segregation forces between the block domains. A perpendicular cylinder-forming block copolymer with a strong segregation force between the block domains displayed cylinder orientation transition from perpendicular to parallel below the ODT temperature. On the other hand, a perpendicular cylinder-forming block copolymer material with an exceptionally strong segregation force between the block domains maintained its initial perpendicular cylinder orientation up to near the ODT temperature. In both cases of perpendicular cylinderforming block copolymers, submicrometer-scale long-range composition fluctuations were observed well above the ODT temperature due to their intrinsically strong segregation forces between the block domains. [ABSTRACT FROM AUTHOR]

Abstract: Research in vital fields such as micro/opto-electronics, fuel cells and tissue engineering calls for fabrication of functional structures with optimal harvesting or perfusion of matter, energy and information, via permeation and transport through random branched conduit networks. This article reviews research aimed at establishing and investigating universal, scalable manufacturing techniques for materials and structures with stochastic tree architectures, and custom-designed, controlled probabilistic leafage, branch and trunk features. These are achieved by combination of complementary, multiscale fabrication processes for robust, affordable, productive manufacture, such as ultrasonic corrosion texturing, ultrasonic powder consolidation, block copolymer self-assembly, plasma processing of polymers, fiber electrospinning, anodized alumina templating and carbon nano-network deposition. Their process–structure–property relations are studied by microscopic, spectroscopic and other experimentation, coupled with computation via atomistic and continuum simulations. Such modelling will enable design and optimization, as well as real-time identification and process control. Manufacturing synthesis of such processes is illustrated in research related to nanoheaters, nanocomposite foils and tissue scaffolds. The platform illustrates and exemplifies some of the key salient features of nanomanufacturing for scalable production. (This paper was presented as an invited talk in the MNE 2008 Conference, www.mne08.org, www.mne-conf.org). [Copyright &y& Elsevier]