Direct Immersion Annealing of Thin Block Copolymer Films

Constructing a Comprehensive Nanopattern Library through Morphological Transitions of Block Copolymer Surface Micelles via Direct Solvent Immersion

This study establishes a comprehensive library of nanopatterns achievable by a single block copolymer (BCP), ranging from spheres to complex structures like split micelles, flower-like clusters, toroids, disordered micelle arrays, and unspecified unique shapes. The ordinary nanostructures of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) surface micelles deposited on a SiOx surface undergo a unique morphology transformation when immersed directly in solvents. Investigating parameters such as immersion solvents, BCP molecular weight, substrate interactions, and temperature, this work reveals the influence of these parameters on the thermodynamics and kinetics governing the morphology transformation. Additionally, the practical application of BCP nanopattern templates for fabricating metal nanostructures through direct solvent immersion of surface micelles is demonstrated. This approach offers an efficient and effective method for producing diverse nanostructures, with the potential to be employed in nanolithography, catalysts, electronics, membranes, plasmonics, and photonics.

Disclosing Topographical and Chemical Patterns in Confined Films of High-Molecular-Weight Block Copolymers under Controlled Solvothermal Annealing

The microphase separation of high-molecular-weight block copolymers into nanostructured films is strongly dependent on the surface fields. Both, the chain mobility and the effective interaction parameters can lead to deviations from the bulk morphologies in the structures adjacent to the substrate. Resolving frustrated morphologies with domain period L0 above 100 nm is an experimental challenge. Here, solvothermal annealing was used to assess the contribution of elevated temperatures of the vapor Tv and of the substrate Ts on the evolution of the microphase-separated structures in thin films symmetric of polystyrene-b-poly(2vinylpyridine) block copolymer (PS-PVP) with L0 about 120 nm. Pronounced topographic mesh-like and stripe patterns develop on a time scale of min and are attributed to the perforated lamella (PL) and up-standing lamella phases. By setting Tv/Ts combinations it is possible to tune the sizes of the resulting PL patterns by almost 10%. Resolving chemical periodicity using selective metallization of the structures revealed multiplication of the topographic stripes, i.e., complex segregation of the component within the topographic pattern, presumably as a result of morphological phase transition from initial non-equilibrium spherical morphology. Reported results reveal approaches to tune the topographical and chemical periodicity of microphase separation of high-molecular-weight block copolymers under strong confinement, which is essential for exploiting these structures as functional templates.

Pressure Indicator Composite Films via Compressive Deformation of a Translucent Matrix Containing a Contrasting Filler

A neglected mechanism for pressure-responsive color change is demonstrated using cellulose acetate composites prepared by direct (solvent) immersion annealing (DIA), with different loadings of activated charcoal filler. Namely, compressive plastic deformation of the translucent cellulose acetate leads to a decrease in the optical path length and a concomitant increase in the visibility of the opaque contrasting filler. Composites bearing 1-7 wt% activated charcoal exhibited a linear relationship between applied pressure and resulting pressure mark brightness in the range of 12-56 MPa. Comparison of pressure mark patterns with cross-sectional scanning electron microscopy (SEM) supports the importance of the porous morphology arising from DIA for the tuning of the pressure indicator sensitivity. A simple ball drop test is used to illustrate the robustness and utility of these indicators in optical impact assessment.

Preparation, Properties, and Bioapplications of Block Copolymer Nanopatterns

Block copolymer (BCP) self-assembly has emerged as a feasible method for large-scale fabrication with remarkable precision - features that are not common for most of the nanofabrication techniques. In this review, recent advancements in the molecular design of BCP along with state-of-the-art processing methodologies based on microphase separation alone or its combination with different lithography methods are presented. Furthermore, the bioapplications of the generated nanopatterns in the development of protein arrays, cell-selective surfaces, and antibacterial coatings are explored. Finally, the current challenges in the field are outlined and the potential breakthroughs that can be achieved by adopting BCP approaches already applied in the fabrication of electronic devices are discussed.

Roles of aqueous nonsolvents influencing the dynamic stability of poly-(n-butyl methacrylate) thin films at biologically relevant temperatures

Poly-(n-butyl methacrylate) (PnBMA) is an important polymer in biomedical applications. Here we study the stability of PnBMA thin films prepared on top of slippery silicon substrates and exposed to nonsolvent aqueous incubation media like water and phosphate-buffered saline (PBS) at temperatures relevant to biological applications (37 °C, 25 °C and 4 °C). Dewetting hole growth experiments allowed us to probe the instability in PnBMA films upon incubation followed by thermal annealing. From the early stage of dewetting hole growth dynamics, we inferred that the stability of the thin PnBMA films decreases as a function of the duration and temperature of incubation, even though the films were found not to readily dewet at room temperature after incubation. It is also observed that water incubation makes films more unstable than incubation in PBS. We explained our observations as a combined effect of (i) an increase in surface energy of the PnBMA film due to incubation, (ii) an increased destabilizing effect due to the dominant polar interactions between the incubation medium and the PnBMA film and (iii) the plasticization effect of PnBMA films by the incubation media. Plasticization resulted in a decrease in the modulus of PnBMA thin films as a function of incubation time. The viscosity of PnBMA films upon incubation was found to be coupled to the decreasing modulus. Thus we infer that incubation in common aqueous nonsolvents can detrimentally affect the stability of polymers limiting their specific usages through a complex interplay of multiple molecular level phenomena.

Hiking down the Free Energy Landscape Using Sequential Solvent and Thermal Processing for Versatile Ordering of Block Copolymer Films

The kinetics and morphology of the ordering of block copolymer (BCP) films are highly dependent on the processing pathway, as the enthalpic and entropic forces driving the ordering processes can be quite different depending on process history. We may gain some understanding and control of this variability of BCP morphology with processing history through a consideration of the free energy landscape of the BCP material and a consideration of how the processing procedure moves the system through this energy landscape in a way that avoids having the system becoming trapped into well-defined metastable minima having a higher free energy than the target low free energy ordered structure. It is well known that standard thermal annealing (TA) of BCPs leads to structures corresponding to a well-defined stable free energy minimum; however, the BCP must be annealed for a very long time before the target low free energy structures can be achieved. Herein, we show that the same target low-energy structure can be achieved relatively quickly by subjecting as-cast films to an initial solvent annealing [direct immersion annealing (DIA) or solvent vapor annealing (SVA)] procedure, followed by a short period of TA. This process relies on lowering the activation energy barrier by reducing the glass-transition temperature through DIA (or SVA), followed by a multi-interface chain rearrangement through sequential TA. This energy landscape approach to ordering should be applicable to the process design for ordering many other complex materials.

Processive Pathways to Metastability in Block Copolymer Thin Films

Block copolymers (BCPs) self-assemble into intricate nanostructures that enhance a multitude of advanced applications in semiconductor processing, membrane science, nanopatterned coatings, nanocomposites, and battery research. Kinetics and thermodynamics of self-assembly are crucial considerations in controlling the nanostructure of BCP thin films. The equilibrium structure is governed by a molecular architecture and the chemistry of its repeat units. An enormous library of materials has been synthesized and they naturally produce a rich equilibrium phase diagram. Non-equilibrium phases could potentially broaden the structural diversity of BCPs and relax the synthetic burden of creating new molecules. Furthermore, the reliance on synthesis could be complicated by the scalability and the materials compatibility. Non-equilibrium phases in BCPs, however, are less explored, likely due to the challenges in stabilizing the metastable structures. Over the past few decades, a variety of processing techniques were introduced that influence the phase transformation of BCPs to achieve a wide range of morphologies. Nonetheless, there is a knowledge gap on how different processive pathways can induce and control the non-equilibrium phases in BCP thin films. In this review, we focus on different solvent-induced and thermally induced processive pathways, and their potential to control the non-equilibrium phases with regards to their unique aspects and advantages. Furthermore, we elucidate the limitations of these pathways and discuss the potential avenues for future investigations.

Solvent-Induced Swelling Behaviors of Microphase-Separated Polystyrene-block-Poly(ethylene oxide) Thin Films Investigated Using In Situ Spectroscopic Ellipsometry and Single-Molecule Fluorescence Microscopy

Block copolymers have attracted considerable interest in the fields of nanoscience and nanotechnology because these polymers afford well-defined nanostructures via self-assembly. An in-depth understanding of solvent effects on the physicochemical properties of these microdomains is crucial for their preparation and utilization. Herein, we employed in situ spectroscopic ellipsometry and single-molecule fluorescence techniques to gain detailed insights into microdomain properties in polystyrene-block-poly(ethylene oxide) (PS-b-PEO) films exposed to ethanol- and water-saturated N₂. We observed a quick increase and a subsequent gradual decrease in the ellipsometric thickness of PS-b-PEO films upon exposure to ethanol-saturated N₂. This observation was unexpected because ethanol-saturated N₂ induced negligible thickness change for PS and PEO homopolymer films. The similarity in maximum thickness gain observed under ethanol- and water-saturated N₂ implied the swelling of PEO microdomains. Ethanol vapor permeation through the PEO microdomains was supported by the redshift of the ensemble and single-molecule fluorescence emission of Nile red in PS-b-PEO films. Single-molecule tracking data showed the initial enhancement and subsequent reduction of the diffusion of hydrophilic sulforhodamine B molecules in PS-b-PEO films upon exposure to ethanol-saturated N₂, consistent with the spectroscopic ellipsometry results. The higher ethanol susceptibility of the PEO microdomains was attributable to their amorphous nature, as shown by FTIR data.

Solvent-assisted self-assembly of block copolymer thin films

Solvent-assisted block copolymer self-assembly is a compelling method for processing and advancing practical applications of these materials due to the exceptional level of the control of BCP morphology and significant acceleration of ordering kinetics. Despite substantial experimental and theoretical efforts devoted to understanding of solvent-assisted BCP film ordering, the development of a universal BCP patterning protocol remains elusive; possibly due to a multitude of factors which dictate the self-assembly scenario. The aim of this review is to aggregate both seminal reports and the latest progress in solvent-assisted directed self-assembly and to provide the reader with theoretical background, including the outline of BCP ordering thermodynamics and kinetics phenomena. We also indicate significant BCP research areas and emerging high-tech applications where solvent-assisted processing might play a dominant role.

Thin film block copolymer self-assembly for nanophotonics

The nanophotonic engineering of light-matter interactions has profoundly changed research behind the design and fabrication of optical materials and devices. Metasurfaces-arrays of subwavelength nanostructures that interact resonantly with electromagnetic radiation-have emerged as an integral nanophotonic platform for a new generation of ultrathin lenses, displays, polarizers and other devices. Their success hinges on advances in lithography and nanofabrication in recent decades. While existing nanolithography techniques are suitable for basic research and prototyping, issues of cost, throughput, scalability, and substrate compatibility may preclude their use for many metasurface applications. Patterning via spontaneous self-assembly of block copolymer thin films offers an enticing alternative for nanophotonic manufacturing that is rapid, inexpensive, and applicable to large areas and diverse substrates. This review discusses the advantages and disadvantages of block copolymer-based nanopatterning and highlights recent progress in their use for broadband antireflection, surface enhanced Raman spectroscopy, and other nanophotonic applications. Recent advances in diversification of self-assembled block copolymer nanopatterns and improved processes for enhanced scalability of self-assembled nanopatterning using block copolymers are also discussed, with a spotlight on directions for future research that would enable a wider array of nanophotonic applications.

Pathway-Dependent Grain Coarsening of Block Copolymer Patterns under Controlled Solvent Evaporation

Solvent evaporation annealing (SEA) is a straightforward, single-step casting and annealing method of block copolymers (BCP) processing yielding large-grained morphologies in a very short time. Here, we present a quantitative analysis of BCP grain-coarsening in thin films under controlled evaporation of the solvent. Our study is aimed at understanding time and BCP concentration influence on the rate of the lateral growth of BCP grains. By systematically investigating the coarsening kinetics at various BCP concentrations, we observed a steeply decreasing exponential dependence of the kinetics power-law time exponent on polymer concentration. We used this dependence to formulate a mathematical model of BCP ordering under nonstationary conditions and a 2D, time- and concentration-dependent coarsening rate diagram, which can be used as an aid in engineering the BCP processing pathway in SEA and also in other directed self-assembly methods that utilize BCP-solvent interactions such as solvent vapor annealing.

Control of Phase Morphology of Binary Polymer Grafted Nanoparticle Blend Films via Direct Immersion Annealing

While the phase separation of binary mixtures of chemically different polymer-grafted nanoparticles (PGNPs) is observed to superficially resemble conventional polymer blends, the presence of a "soft" polymer-grafted layer on the inorganic core of these nanoparticles qualitatively alters the phase separation kinetics of these "nanoblends" from the typical pattern of behavior seen in polymer blends and other simple fluids. We investigate this system using a direct immersion annealing method (DIA) that allows for a facile tuning of the PGNPs phase boundary, phase separation kinetics, and the ultimate scale of phase separation after a sufficient "aging" time. In particular, by switching the DIA solvent composition from a selective one (which increases the interaction parameter according to Timmerman's rule) to an overall good solvent for both PGNP components, we can achieve rapid switchability between phase-separated and homogeneous states. Despite a relatively low and non-classical power-law coarsening exponent, the overall phase separation process is completed on a time scale on the order of a few minutes. Moreover, the roughness of the PGNP blend film saturates at a scale that is proportional to the in-plane phase separation pattern scale, as observed in previous blend and block copolymer film studies. The relatively low magnitude of the coarsening exponent n is attributed to a suppression of hydrodynamic interactions between the PGNPs. The DIA method provides a significant opportunity to control the phase separation morphology of PGNP blends by solution processing, and this method is expected to be quite useful in creating advanced materials.

Developing Anisotropy in Self-Assembled Block Copolymers: Methods, Properties, and Applications

Block copolymers (BCPs) self-assembly has continually attracted interest as a means to provide bottom-up control over nanostructures. While various methods have been demonstrated for efficiently ordering BCP nanodomains, most of them do not generically afford control of nanostructural orientation. For many applications of BCPs, such as energy storage, microelectronics, and separation membranes, alignment of nanodomains is a key requirement for enabling their practical use or enhancing materials performance. This review focuses on summarizing research progress on the development of anisotropy in BCP systems, covering a variety of topics from established aligning techniques, resultant material properties, and the associated applications. Specifically, the significance of aligning nanostructures and the anisotropic properties of BCPs is discussed and highlighted by demonstrating a few promising applications. Finally, the challenges and outlook are presented to further implement aligned BCPs into practical nanotechnological applications, where exciting opportunities exist.

Physicochemical defect guided dewetting of ultrathin films to fabricate nanoscale patterns

Pathways to fabricate self-organized nanostructures have been identified exploiting the instabilities of ultrathin (<100 nm) polystyrene (PS) film on the polydimethylsiloxane (PDMS) substrates loaded with discrete and closely packed gold nanoparticles (AuNPs). The AuNPs were deposited on the PDMS substrates by chemical treatment, and the size and periodicity of the AuNPs were varied before coating the PS films. The study unveils that the physicochemical heterogeneity created by the AuNPs on the PDMS surface could guide the hole-formation, influence the average spacing between the holes formed at the initial dewetting stage, and affects the spacing and periodicity of the droplets formed at the end of the dewetting phase. The size and spacing of the holes and the droplets could be tuned by varying the nanoparticle loading on the PDMS substrate. Interestingly, as compared to the dewetting of PS films on the homogeneous PDMS surfaces, the AuNP guided dewetted patterns show ten-fold miniaturization, leading to the formation of the micro-holes and nanodroplets. The spacing between the droplets could also see a ten-fold reduction resulting in high-density random patterns on the PDMS substrate. Further, the use of a physicochemical substrate with varying density of physicochemical heterogeneities could impose a long-range order to the dewetted patterns to develop a gradient surface. The reported results can be of significance in the fabrication of high-density nanostructures exploiting the self-organized instabilities of thin polymers films.

Large-Grained Cylindrical Block Copolymer Morphologies by One-Step Room-Temperature Casting

We report a facile method of ordering block copolymer (BCP) morphologies in which the conventional two-step casting and annealing steps are replaced by a single-step process where microphase separation and grain coarsening are seamlessly integrated within the casting protocol. This is achieved by slowing down solvent evaporation during casting by introducing a nonvolatile solvent into the BCP casting solution that effectively prolongs the duration of the grain-growth phase. We demonstrate the utility of this solvent evaporation annealing (SEA) method by producing well-ordered large-molecular-weight BCP thin films in a total processing time shorter than 3 min without resorting to any extra laboratory equipment other than a basic casting device, i.e., spin- or blade-coater. By analyzing the morphologies of the quenched samples, we identify a relatively narrow range of polymer concentration in the wet film, just above the order-disorder concentration, to be critical for obtaining large-grained morphologies. This finding is corroborated by the analysis of the grain-growth kinetics of horizontally oriented cylindrical domains where relatively large growth exponents (1/2) are observed, indicative of a more rapid defect-annihilation mechanism in the concentrated BCP solution than in thermally annealed BCP melts. Furthermore, the analysis of temperature-resolved kinetics data allows us to calculate the Arrhenius activation energy of the grain coarsening in this one-step BCP ordering process.

Kinetic Monitoring of Block Copolymer Self-Assembly Using In Situ Spectroscopic Ellipsometry

Understanding the kinetic pathways of self-assembly in block copolymers (BCPs) has been a long-standing challenge, mostly due to limitations of in situ monitoring techniques. Here, we demonstrate an approach that uses optical birefringence, determined by spectroscopic ellipsometry (SE), as a measure of domain formation in cylinder- and lamellae-forming BCP films. The rapid experimental acquisition time in SE (ca. 1 sec) enables monitoring of the assembly/disassembly kinetics of BCP films during solvent-vapor annealing (SVA). We demonstrate that upon SVA, BCP films form ordered domains that are stable in the swollen state, but disorder upon rapid drying. Surprisingly, the disassembly during drying strongly depends on the duration of solvent exposure in the swollen state, explaining previous observations of loss of order in SVA processes. SE thus allows for decoupling of BCP self-assembly and disordering that occurs during solvent annealing and solvent evaporation, which is difficult to probe using other, slower techniques.

Macroscopic Alignment of Block Copolymers on Silicon Substrates by Laser Annealing

Laser annealing is a competitive alternative to conventional oven annealing of block copolymer (BCP) thin films enabling rapid acceleration and precise spatial control of the self-assembly process. Localized heating by a moving laser beam (zone annealing), taking advantage of steep temperature gradients, can additionally yield aligned morphologies. In its original implementation it was limited to specialized germanium-coated glass substrates, which absorb visible light and exhibit low-enough thermal conductivity to facilitate heating at relatively low irradiation power density. Here, we demonstrate a recent advance in laser zone annealing, which utilizes a powerful fiber-coupled near-IR laser source allowing rapid BCP annealing over a large area on conventional silicon wafers. The annealing coupled with photothermal shearing yields macroscopically aligned BCP films, which are used as templates for patterning metallic nanowires. We also report a facile method of transferring laser-annealed BCP films onto arbitrary surfaces. The transfer process allows patterning substrates with a highly corrugated surface and single-step rapid fabrication of multilayered nanomaterials with complex morphologies.

Synthesis of amphiphilic poly(ethylene glycol)-block-poly(methyl methacrylate) containing trityl ether acid cleavable junction group and its self-assembly into ordered nanoporous thin films

A strategy for the synthesis of well defined poly(ethylene glycol)-block-poly(methyl methacrylate) diblock copolymers containing trityl ether acid cleavable junctions is demonstrated. This approach is achieved by using a combination of poly(ethylene glycol) macroinitiator containing a trityl ether end group, which is susceptible to acid cleavage, and atom transfer radical polymerization technique. The trityl ether linkage between blocks can be readily cleaved in solution or in solid phase under very mild acid condition, which has been confirmed by 1H NMR. These diblock copolymers have been used to successfully fabricate nanoporous thin films by acid cleavage of trityl ether junction followed by complete removal of poly(ethylene glycol) block. The fabricated nanoporous thin films may have a wide range of application such as Recessed Nanodisk-array electrode (RNE) or as a template to fabricate nanoelectrode array for senor applications.

Temperature-Controlled Solvent Vapor Annealing of Thin Block Copolymer Films

Solvent vapor annealing is as an effective and versatile alternative to thermal annealing to equilibrate and control the assembly of polymer chains in thin films. Here, we present scientific and practical aspects of the solvent vapor annealing method, including the discussion of such factors as non-equilibrium conformational states and chain dynamics in thin films in the presence of solvent. Homopolymer and block copolymer films have been used in model studies to evaluate the robustness and the reproducibility of the solvent vapor processing, as well as to assess polymer-solvent interactions under confinement. Advantages of utilizing a well-controlled solvent vapor environment, including practically interesting regimes of weakly saturated vapor leading to poorly swollen states, are discussed. Special focus is given to dual temperature control over the set-up instrumentation and to the potential of solvo-thermal annealing. The evaluated insights into annealing dynamics derived from the studies on block copolymer films can be applied to improve the processing of thin films of crystalline and conjugated polymers as well as polymer composite in confined geometries.

Pathway-engineering for highly-aligned block copolymer arrays

While the ultimate driving force in self-assembly is energy minimization and the corresponding evolution towards equilibrium, kinetic effects can also play a very strong role. These kinetic effects, such as trapping in metastable states, slow coarsening kinetics, and pathway-dependent assembly, are often viewed as complications to be overcome. Here, we instead exploit these effects to engineer a desired final nano-structure in a block copolymer thin film, by selecting a particular ordering pathway through the self-assembly energy landscape. In particular, we combine photothermal shearing with high-temperature annealing to yield hexagonal arrays of block copolymer cylinders that are aligned in a single prescribed direction over macroscopic sample dimensions. Photothermal shearing is first used to generate a highly-aligned horizontal cylinder state, with subsequent thermal processing used to reorient the morphology to the vertical cylinder state in a templated manner. Finally, we demonstrate the successful transfer of engineered morphologies into inorganic replicas.

Rapid ordering of block copolymer thin films

Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times-hours or days-required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.

Influence of film structure on the dewetting kinetics of thin polymer films in the solvent annealing process

On a non-wetting solid substrate, the solvent annealing process of a thin polymer film includes the swelling process and the dewetting process. Owing to difficulties in the in situ analysis of the two processes simultaneously, a quantitative study on the solvent annealing process of thin polymer films on the non-wetting solid substrate is extremely rare. In this paper, we design an experimental method by combining spectroscopic ellipsometry with optical microscopy to achieve the simultaneous in situ study. Using this method, we investigate the influence of the structure of swollen film on its dewetting kinetics during the solvent annealing process. The results show that for a thin PS film with low Mw (Mw = 4.1 kg mol(-1)), acetone molecules can form an ultrathin enriched layer between the PS film and the solid substrate during the swelling process. The presence of the acetone enriched layer accounts for the exponential kinetic behavior in the case of a thin PS film with low Mw. However, the acetone enriched layer is not observed in the case of a thin PS film with high Mw (Mw = 400 kg mol(-1)) and the slippage effect of polymer chains is valid during the dewetting process.

Directed Self-Assembly of Block Copolymers for High Breakdown Strength Polymer Film Capacitors

Emerging needs for fast charge/discharge yet high-power, lightweight, and flexible electronics requires the use of polymer-film-based solid-state capacitors with high energy densities. Fast charge/discharge rates of film capacitors on the order of microseconds are not achievable with slower charging conventional batteries, supercapacitors and related hybrid technologies. However, the current energy densities of polymer film capacitors fall short of rising demand, and could be significantly enhanced by increasing the breakdown strength (EBD) and dielectric permittivity (εr) of the polymer films. Co-extruded two-homopolymer component multilayered films have demonstrated much promise in this regard showing higher EBD over that of component polymers. Multilayered films can also help incorporate functional features besides energy storage, such as enhanced optical, mechanical, thermal and barrier properties. In this work, we report accomplishing multilayer, multicomponent block copolymer dielectric films (BCDF) with soft-shear driven highly oriented self-assembled lamellar diblock copolymers (BCP) as a novel application of this important class of self-assembling materials. Results of a model PS-b-PMMA system show ∼50% enhancement in EBD of self-assembled multilayer lamellar BCP films compared to unordered as-cast films, indicating that the breakdown is highly sensitive to the nanostructure of the BCP. The enhancement in EBD is attributed to the "barrier effect", where the multiple interfaces between the lamellae block components act as barriers to the dielectric breakdown through the film. The increase in EBD corresponds to more than doubling the energy storage capacity using a straightforward directed self-assembly strategy. This approach opens a new nanomaterial paradigm for designing high energy density dielectric materials.