Copolymer Thin Films Research Articles

Improved Exciton Bandwidth and Edge-On Oriented Ordering of Donor–Acceptor Copolymer Thin Films

Improved Exciton Bandwidth and Edge-On Oriented Ordering of Donor–Acceptor Copolymer Thin Films

Bayesian model calibration for diblock copolymer thin film self-assembly using power spectrum of microscopy data and machine learning surrogate

Identifying parameters of computational models from experimental data, or model calibration, is fundamental for assessing and improving the predictability and reliability of computer simulations. In this work, we propose a method for Bayesian calibration of models that predict morphological patterns of diblock copolymer (Di-BCP) thin film self-assembly while accounting for various sources of uncertainties in pattern formation and data acquisition. This method extracts the azimuthally-averaged power spectrum (AAPS) of the top-down microscopy characterization of Di-BCP thin film patterns as summary statistics for Bayesian inference of model parameters via the pseudo-marginal method. We derive the analytical and approximate form of a conditional likelihood for the AAPS of image data. We demonstrate that AAPS-based image data reduction retains the mutual information, particularly on important length scales, between image data and model parameters while being relatively agnostic to the aleatoric uncertainties associated with the random long-range disorder of Di-BCP patterns. Additionally, we propose a phase-informed prior distribution for Bayesian model calibration. Furthermore, reducing image data to AAPS enables us to efficiently build surrogate models to accelerate the proposed Bayesian model calibration procedure. We present the formulation and training of two multi-layer perceptrons for approximating the parameter-to-spectrum map, which enables fast integrated likelihood evaluations. We validate the proposed Bayesian model calibration method through numerical examples, for which the neural network surrogate delivers a fivefold reduction of the number of model simulations performed for a single calibration task.

Strategy to simulate and fit 2D grazing-incidence small-angle X-ray scattering patterns of nanostructured thin films.

Grazing-incidence small-angle X-ray scattering (GISAXS) is a widely used method for the characterization of the nanostructure of supported thin films and enables time-resolved in situ measurements. The 2D scattering patterns contain detailed information about the nanostructures within the film and at its surface. However, this information is distorted not only by the reflection of the X-ray beam at the substrate-film interface and its refraction at the film surface but also by scattering of the substrate, the sample holder and other types of parasitic background scattering. In this work, a new, efficient strategy to simulate and fit 2D GISAXS patterns that explicitly includes these effects is introduced and demonstrated for (i) a model case nanostructured thin film on a substrate and (ii) experimental data from a microphase-separated block copolymer thin film. To make the protocol efficient, characteristic linecuts through the 2D GISAXS patterns, where the different contributions dominate, are analysed. The contributions of the substrate and the parasitic background scattering - which ideally are measured separately - are determined first and are used in the analysis of the 2D GISAXS patterns of the nanostructured, supported film. The nanostructures at the film surface and within the film are added step by step to the real-space model of the simulation, and their structural parameters are determined by minimizing the difference between simulated and experimental scattering patterns in the selected linecuts. Although in the present work the strategy is adapted for and tested with BornAgain, it can be easily used with other types of simulation software. The strategy is also applicable to grazing-incidence small-angle neutron scattering.

Directed self‐assembly of block copolymer thin films via momentary thickness gradients

AbstractIn this study, a novel method to fabricate highly aligned lamellar nanostructures in a millimeter‐scale large area was demonstrated by directing the self‐assembly of block copolymer (BCP) thin films with a temporary thickness‐gradient micropattern via simple two‐step thermal annealing. In the first step of thermal annealing, the BCP nanostructure is latently guided by a phenomenon known as “geometric anchoring” for the area with a thickness gradient. The second annealing step causes thermal reflow of the height gradient micropattern with a sufficiently large curvature to flatten the micropattern. The shear stress generated by thermal reflow enlarged the grain of the BCP nanostructure, resulting in a highly aligned lamellar pattern over the entire area. Finally, the formation of periodic nanopatterns in large area was ensured by performing grazing‐incidence small‐angle x‐ray scattering. This innovative approach in directing the BCP self‐assembly promotes the fabrication of highly aligned nanostructures in large areas through cost‐effective and simple thermal imprinting method and designed two‐step heat treatment.

Unfolding the Correlation between Solution Aggregation and Solid-State Crystal Orientation in Donor-Acceptor Copolymers via Solvent Additive Processing.

Tailoring the crystal orientation of donor-acceptor (D-A) copolymers is vital for boosting the performance of optoelectronic devices. Despite recent advances in controlling the crystal orientation of D-A copolymers in films, the investigation into their aggregates in solution and the correlation between the solution aggregates and solid-state crystal orientation has been limited. Herein, an effective solvent additive strategy is reported for tuning solution aggregates and the consequent solid-state structures of 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)). Specifically, the addition of 1-decanethiol (10-thiol) to the P(NDI2OD-T2) chloroform solution promoted the aggregation of P(NDI2OD-T2) chains because of the improved planarization of the backbones, which changed their crystal orientation in the film from coexisting edge-on and face-on to dominant edge-on when produced by drop-casting. The mechanism of this crystal orientation transformation is elucidated based on the interaction between 10-thiol and the side chains of P(NDI2OD-T2). The optical properties of P(NDI2OD-T2) films with different crystalline structures are closely correlated. Notably, the 10-thiol-enabled facile tailoring of the crystal orientation in P(NDI2OD-T2) can be readily applied to other D-A copolymers of interest. The findings of this study highlight a robust solvent additive strategy for regulating solution aggregates and crystal orientation in D-A copolymer films, which have applications in many optoelectronic devices.

Periodic Arrays of Dopants in Silicon by Ultralow Energy Implantation of Phosphorus Ions through a Block Copolymer Thin Film.

In this work, block copolymer lithography and ultralow energy ion implantation are combined to obtain nanovolumes with high concentrations of phosphorus atoms periodically disposed over a macroscopic area in a p-type silicon substrate. The high dose of implanted dopants grants a local amorphization of the silicon substrate. In this condition, phosphorus is activated by solid phase epitaxial regrowth (SPER) of the implanted region with a relatively low temperature thermal treatment preventing diffusion of phosphorus atoms and preserving their spatial localization. Surface morphology of the sample (AFM, SEM), crystallinity of the silicon substrate (UV Raman), and position of the phosphorus atoms (STEM- EDX, ToF-SIMS) are monitored during the process. Electrostatic potential (KPFM) and the conductivity (C-AFM) maps of the sample surface upon dopant activation are compatible with simulated I-V characteristics, suggesting the presence of an array of not ideal but working p-n nanojunctions. The proposed approach paves the way for further investigations on the possibility to modulate the dopant distribution within a silicon substrate at the nanoscale by changing the characteristic dimension of the self-assembled BCP film.

KCl-Modulated Hydration and Subsequent Thermoresponsive Behavior of Poly(sulfobetaine)-Based Diblock Copolymer Thin Films

The KCl-modulated swelling of double thermoresponsive diblock copolymer (DBC) thin films in D2O atmosphere and their subsequent responsive behavior are investigated via spectral reflectance (SR), in situ time-of-flight neutron reflectometry (ToF-NR), and Fourier-transform infrared (FT-IR) spectroscopy. The copolymer consists of a short zwitterionic (poly(4-(N-(3-methacrylamidopropyl)-N,N-dimethylammonio) butane-1-sulfonate)) (PSBP) block and a long non-ionic poly(N-isopropylmethacrylamide) (PNIPMAM) block. DBC thin films are prepared via spin-coating from solutions containing 5 mM or devoid of KCl. The addition of KCl to the DBC thin films leads to a higher swelling ratio and D2O content during vapor treatment with D2O. Upon the subsequent heating of the hydrated DBC films, the films swell further and reach a maximum thickness before contracting. Two separate volume phase transition temperatures (VPTTs) are observed, namely where a further swelling plateau is reached (VPTTfs), and where contraction starts (VPTTc). Based on complementary SR studies of the effect of KCl on the swelling behavior of the respective PSBP and PNIPMAM homopolymer thin films, we conclude that the “further-swelling” period is mainly a consequence of the UCST-type phase transition of PSBP, whereas the “film contraction” period is due to the LCST-type phase transition of PNIPMAM in thin-film geometry. We observe that KCl reduces the VPTTc of the PNIPMAM blocks. Moreover, the salt migrates or aggregates inside the thin film upon heating, thereby forming a KCl enrichment layer in the intermediate section of the film. Furthermore, the observations by FT-IR prove that macroscopic and mesoscopic D2O absorption and desorption are correlated with the effect of KCl on hydration and de-hydration of the hydrophilic groups.

Crystallization of Poly(ethylene oxide)-Based Triblock Copolymers in Films Swollen-Rich in Solvent Vapors

In this study, we employed a polymer processing method based on solvent vapor annealing in a confined environment to swell-rich thin films of polybutadiene-b-poly(2-vinylpyridine)-b-poly(ethylene oxide) triblock copolymers and to promote their crystallization. As revealed by optical and atomic force microscopy, thin films of triblock copolymers containing a rather short crystalline poly(ethylene oxide) block that was massively obstructed by the other two blocks were unable to crystallize following the spin-casting process, and their further swelling in solvent vapors was necessary in order to produce polymeric crystals displaying a dendritic morphology. In comparison, thin films of triblock copolymers containing a much longer poly(ethylene oxide) block that was less obstructed by the other two blocks were shown to crystallize into dendritic structures right after the spin-casting procedure, as well as upon rich swelling in solvent vapors.

Interface Manipulations Using Cross-Linked Underlayers and Surface-Active Diblock Copolymers to Extend Morphological Diversity in High-χ Diblock Copolymer Thin Films

Top and bottom interfaces of high-χ cylinder-forming polystyrene-block-maltoheptaose (PS-b-MH) diblock copolymer (BCP) thin films are manipulated using cross-linked copolymer underlayers and a fluorinated phase-preferential surface-active polymer (SAP) additive to direct the self-assembly (both morphology and orientation) of BCP microdomains into sub-10 nm patterns. A series of four photo-cross-linkable statistical copolymers with various contents of styrene, a 4-vinylbenzyl azide cross-linker, and a carbohydrate-based acrylamide are processed into 15 nm-thick cross-linked passivation layers on silicon substrates. A partially fluorinated analogue of the PS-b-MH phase-preferential SAP additive is designed to tune the surface energy of the top interface. The self-assembly of PS-b-MH thin films on top of different cross-linked underlayers and including 0-20 wt % of SAP additive is investigated by atomic force microscopy and synchrotron grazing incidence small-angle X-ray scattering analysis. The precise manipulation of the interfaces of ca. 30 nm thick PS-b-MH films not only allows the control of the in-plane/out-of-plane orientation of hexagonally packed (HEX) cylinders but also promotes epitaxial order-order transitions from HEX cylinders to either face-centered orthorhombic or body-centered cubic spheres without modifying the volume fraction of both blocks. This general approach paves the way for the controlled self-assembly of other high-χ BCP systems.

Photoinduced Solubility Modulation in the Copolymers of Fluoroalkyl, Spiropyranyl, and Isobornyl Methacrylates

This article reports photoinduced solubility modulation in copolymer thin films derived from spiropyranyl, perfluoroalkyl, and isobornyl methacrylates. A random copolymer of spiropyranyl methacrylate (SPMA) and 1H,1H,2H,2H-perfluorooctyl methacrylate (FOMA) was first prepared in the absence of isobornyl methacrylate (IBMA). The resulting as-prepared thin film could be dissolved in highly fluorinated or fluorous solvents but became insoluble following exposure to UV light (λ = 365 nm) via the photoisomerization transformation of spiropyran units into merocyanine moieties. On the other hand, the incorporation of IBMA into the copolymer structure above a certain threshold resulted in copolymers exhibiting the opposite dissolution behavior. UV–vis spectroscopic measurements on the copolymer films and solutions indicated that dipolar attraction between the photoisomerized merocyanine moieties contributed to the decrease in solubility. The incorporation of IBMA into the copolymer chains diluted the merocyanine moieties and increased their glass-transition temperature, resulting in the disruption of the intermolecular attraction and an increase in the solubility of the UV-exposed polymer chains. These results suggested that stencils could be developed without additives to generate strong acid molecules or free radicals in polymer thin films. The proposed processing technique for fluoroalkylated copolymers was thus tested in the fabrication of orthogonal copolymer stencils and demonstrated to be a useful tool for the pixel patterning of chemically vulnerable organic light-emitting diodes.

Properties and molecular self‐assembly of liquid crystalline hard–hard diblock and hard–soft–hard triblock copolymers influenced by Flory–Huggins interaction parameter and volume fraction of distinct segments

AbstractTwo series of hybrid liquid crystalline (LC) diblock copolymers (DBCs) and triblock copolymers (TBCs) composed of hard and soft blocks with great control over their molecular masses, dispersities (Mw/Mn = Đ ≤ 1.38) and compositions were prepared via reversible addition‐fragmentation chain transfer polymerization in anisole solvent using new p‐dodecylphenyl‐N‐acrylamide monomer, azobisisobutyronitrile initiator, poly(2‐[2‐(4‐cyano‐azobenzene‐4‐oxy)ethylene‐oxy]ethyl methacrylate) and poly(2‐[2‐(4‐cyano‐azobenzene‐4‐oxy)ethylene‐oxy]ethyl methacrylate)‐block‐poly(n‐butyl methacrylate) macroinitiators. Structures and properties of BCs were characterized by proton nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimeter, optical polarizing microscope, atomic force microscope and grazing‐incidence small angle X‐ray scattering. Kinetic behavior indicated that block copolymerization proceeded with controlled/living characteristics. Every BCs revealed three endothermic transitions corresponding to glassy phase transition, smectic‐to‐nematic phase transition (TS‐N) and melting phase transition. DBC‐1, DBC‐2, TBC‐1 and TBC‐2 with high‐LC volume fractions exhibited strong TS‐N contrasted to DBC‐3, DBC‐4, TBC‐3 and TBC‐4 having low‐LC contents. DBC‐1, DBC‐2, DBC‐3, TBC‐1 and TBC‐2 evidenced smectic C structure while TBC‐3 containing low‐LC segment (39 wt%) showed nematic structure. Morphologies of block copolymer thin films in mixed solvent (Tetrahydrofuran/cyclohexane) vapor annealing system varied significantly, depending on the volume fractions of building blocks and the interactions between the blocks and solvents.

Direct Visualization of the Self-Alignment Process for Nanostructured Block Copolymer Thin Films by Transmission Electron Microscopy

Herein, this work aims to directly visualize the morphological evolution of the controlled self-assembly of star-block polystyrene-block-polydimethylsiloxane (PS-b-PDMS) thin films via in situ transmission electron microscopy (TEM) observations. With an environmental chip, possessing a built-in metal wire-based microheater fabricated by the microelectromechanical system (MEMS) technique, in situ TEM observations can be conducted under low-dose conditions to investigate the development of film-spanning perpendicular cylinders in the block copolymer (BCP) thin films via a self-alignment process. Owing to the free-standing condition, a symmetric condition of the BCP thin films can be formed for thermal annealing under vacuum with neutral air surface, whereas an asymmetric condition can be formed by an air plasma treatment on one side of the thin film that creates an end-capped neutral layer. A systematic comparison of the time-resolved self-alignment process in the symmetric and asymmetric conditions can be carried out, giving comprehensive insights for the self-alignment process via the nucleation and growth mechanism.

Selective solvent vapor induced self-assembly of silicon-containing bottlebrush block copolymer thin films to generate mesoporous silicon oxide patterns

Bottlebrush block copolymers (BBCPs) are intriguing architectures that can produce various anisotropic nanostructures dictated by the composition, length of the backbone and the lengths of side-chains. Here, we develop a facial approach toward ordered inorganic silicon oxide patterns and particles on substrates by solvent vapor induced thin film self-assembly of anisotropic bottlebrush block copolymers (BBCP) containing polydimethylsiloxane (PDMS) and polystyrene (PS) side chains. The in-plane cylindrical or stripes-like, spherical, and ordered porous morphologies as well as Janus particles-like morphology were fabricated on the substrate through solvent vapor annealing (SVA). The Janus particle-like morphology consisting of PS heads inserted in PDMS heads were directed to produce meso-to macroporous silicon oxide bowls after oxygen plasma etching. The effects of the solvent vapor on the molecular geometry and morphology of the BBCPs were described, and the influence of the backbone length on the self-assembly behavior of the thin film were discussed. This work demonstrates that silicon-containing BBCPs with a native etch contrast and a large difference in solubility parameters are potential candidates to generate ordered silicon oxide templates of different geometries with periodicity 80–150 nm providing access to length scales larger than linear block copolymers.

Trilayered Block Copolymer Nanostructures Formed by an Iterative Layering Strategy

AbstractNanostructured block copolymer (BCP) thin films enable the formation on‐demand of a variety of periodic patterns at the nanometer scale by tuning the macromolecular BCP characteristics and annealing processes. Significant progress in the control of the self‐assembly has been witnessed over the past decade with the implementation of robust directed self‐assembly methods. However, the self‐assembled structural patterns obtained at equilibrium are limited and methods to expand the range of structural configurations are required to harness additional functionalities. Here, this work demonstrates how polystyrene‐b‐poly(methyl methacrylate) BCP thin layers can be stacked to produce a library of complex 3D hierarchical heterostructures. In this iterative assembly process based on simple building bricks (i.e., immobilized BCP patterns forming Holes, Lines and Dots), the stacking configuration (i.e., self‐assembly and registration) of a BCP thin film is directed with respect to the previous layer using confinement effects and interfacial energy tuning. This responsive layering can lead to intricate 3D Al2O3 structures and opens the way to a broad variety of structural designs toward functional applications.

Block copolymer interfaces investigated by means of NMR, atomic force microscopy and dielectric spectroscopy

Self-assembly of block copolymers (BC) is a key feature for bottom-up patterning that is applied in the fabrication of templates for nanostructured membranes, photonic nanodevices, or solar cells. The wide range of possible BC applications is because the dissimilar blocks can be appropriately selected to form distinct domains with controllable dimensions and functionalities. An important representative of these materials is polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymer. This copolymer is of considerable academic interest and therefore it is examined by a plethora of experimental techniques to elucidate its structure and molecular dynamics. Particularly worth investigating is the interphase, consisting of polymer chains located at the interface of crystallite-amorphous and inter-domain regions, which codetermines the properties of such a system. It is shown that below the melting point of the PEO, the majority of the amorphous PEO are occupying interfacial sites and are represented by the rigid amorphous fraction (RAF) which can be monitored by dielectric and nuclear magnetic resonance spectroscopies. Moreover, two independent NMR spin-diffusion experiments reveal the asymmetrical nature of PS-PEO interface indicating a significant fraction of the PEO phase under the influence of stiff, adjacent polystyrene. An analysis of complementary thermal calorimetry and X-ray scattering data confirms the presence of microphase-separated morphology as well as the semicrystalline nature of PEO component. Lamelar domain architecture was confirmed by atomic force microscopy data acquired in the case of thin copolymer film.

Self-assembled biodegradable block copolymer precursors for the generation of nanoporous poly(trimethylene carbonate) thin films

Even though the domain of nanoporous template manufacturing from self-assembled block copolymers is in full expansion, challenging studies addressing innovative biodegradable block copolymer assemblies are still not reported. Herein, we address the usage of an original biodegradable precursor to prepare nanoporous thin films: the PTMC-b-PDLLA-b-PTMC triblock copolymer. The copolymer is designed to have a favorable interaction parameter for phase-separation, which was confirmed by differential scanning calorimetry by the appearance of two distinctive glass transition temperatures, corresponding to each of the blocks. Thin films are firstly produced by spin-coating and two methods are investigated for achieving organized self-assembly of the system: solvent evaporation and solvent vapor annealing. Well-organized bicontinuous nanoscopic phase-separated morphologies consisting of PTMC and PDLLA domains are achieved under precise solvent vapor annealing conditions for a particular triblock copolymer composition. Triblock copolymer self-assembly is compared to the one occurring in PTMC/PDLLA blends where no ordered phase-separation is observed. Moreover, thin films photo-crosslinking of previously methacrylated PTMC end-blocks, beneficial to the stability and cohesion of the PTMC phase, as well as mechanical strength of the porous matrix, proved to preserve the phase separation. From the optimal oriented block copolymer thin films, selective etching via PDLLA mild hydrolysis resulted in nanoporous PTMC with maintained long-range order and stability. Such approach to generate nanoporous PTMC could have great potential in both biomedical applications and the energy field.

Spatiotemporal Mapping of Hole Nucleation and Growth during Block Copolymer Terracing with High-Speed Atomic Force Microscopy.

As a platform for investigating two-dimensional phase separation, we track the structural evolution of block copolymer thin films during thermal annealing with environmentally controlled atomic force microscopy (AFM). Upon thermal annealing, block copolymer films with incommensurate thickness separate into a terraced morphology decorated with holes. With in situ imaging at 200 °C, we follow the continuous progression of terrace formation in a single region of a cylinder-forming poly(styrene-block-methyl methacrylate) thin film, beginning with the disordered morphology on an unpatterned silicon substrate and continuing through nucleation and coarsening stages. Topographic AFM imaging with nanoscale resolution simultaneously captures ensemble hole growth statistics while locally tracking polymer diffusion through measurements of the film thickness. At early times, we observe homogeneous hole nucleation and isotropic growth, with kinetics following the predictions of classical nucleation theory. At later times, however, we find anomalous hole growth which arises due to the combination of Ostwald ripening and coalescence mechanisms. In each case, our real-space observations highlight the importance of hole interactions for determining coarsening kinetics, mediated either through the interconnected phase for Ostwald ripening or through binary collision events for coalescence.

Extreme UV Resist Exhibiting Synergism between Chemical and Physical Crosslinking Mechanisms.

Carbon-fluorine bonds in fluorinated molecules can undergo homolytic cleavage reactions when electrons are injected, and the resulting radicals combine to form network structures characterized by reduced solubility. This crosslinking chemistry suggests a new category of patterning materials that function under electron beam (e-beam) and extreme ultraviolet (EUV) lithographic conditions. Although this chemistry enables the production of 50 nm or smaller-sized features of simple fluoroalkylated polymers, it is limited by the need for relatively large amounts of irradiation energy to achieve required solubility changes. Therefore, this study was undertaken to devise a sensitivity-enhancing strategy based on a synergistic combination of radical crosslinking and hydrogen-bonding interactions between highly fluoroalkylated copolymers. An alternating copolymer was synthesized using tert-butoxystyrene and a fluoroalkylated maleimide, the former of which produces active hydrogens through catalytic acidolysis reactions. When the polymer was blended with a catalytic amount of a photoacid generator and subjected to lithographic patterning tests under e-beam and EUV irradiation, the deprotection reactions of tert-butoxy moieties proceeded at room temperature and led to a solubility decrease. We presume the small number of hydroxyl moieties produced formed an intermolecular hydrogen-bonding network, which acted synergistically with the covalent crosslinks generated by C-F bonds. When 30 nm features of copolymer thin films were fabricated by EUV lithography, sensitivity was improved by 25-34% without significant deterioration of pattern quality, especially line-edge roughness. These results demonstrate that EUV resists with improved patterning capabilities can be achieved by combining catalytic acidolysis reactions and noncatalytic crosslinking chemistry.

CVD Deposited Epoxy Copolymers as Protective Coatings for Optical Surfaces.

Copolymer thin films of glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EGDMA) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) were synthesized via initiated chemical vapor deposition (iCVD) as protective coatings for optical surfaces. Chemical durability in various solvents, corrosion resistance, adhesion to substrate, thermal resistance and optical transmittance of the films were evaluated. Crosslinked thin films exhibited high chemical resistance to strong organic solvents and excellent adhesion to substrates. Poly(GMA-co-EGDMA) and poly(GMA-co-V4D4) copolymers demonstrated protection against water (<1% thickness loss), high salt resistance (<1.5% thickness loss), and high optical transparency (~90% in visible spectrum) making them ideal coating materials for optical surfaces. Combining increased mechanical properties of GMA and chemical durability V4D4, the iCVD process provides a fast and low-cost alternative for the fabrication of protective coatings.

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.