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

Abstract

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.

Single-Ion Conducting Polymeric Protective Interlayer for Stable Solid Lithium-Metal Batteries

“…1,10 With high ionic conductivity, mechanical robustness, and unit cationic transport number, inorganic electrolytes are usually fragile and brittle with poor interfacial contact with electrodes. 11 In contrast, the polymer electrolyte exhibits several merits such as good compatibility with the electrode, mechanical flexibility, improved processibility for large-scale manufacturing, and easy-to-deform characteristic for emerging applications. 12 Since the discovery of solvation of Li salt by poly(ethylene oxide) (PEO) in the 1970s, the significant results of salt-doped polymer electrolytes are achieved, with good potential for solid-state LMBs.…”

“…The traditional liquid-electrolyte-based lithium-ion batteries cannot achieve next-generation energy storage devices due to their limited safety and energy density. − Developing solid-state Li-metal batteries (LMBs) with combined solid electrolytes and high-capability Li-metal anodes is especially attractive due to high energy density (bipolar stacking and high capacity metal anode), improved safety (the absence of liquid components), and prolonged lifetime (dendrite-free anode). − Solid-state electrolytes, as high-priority materials for solid-state LMBs, can be generally classified into two distinct families: inorganic/ceramic electrolytes and polymer electrolytes. , With high ionic conductivity, mechanical robustness, and unit cationic transport number, inorganic electrolytes are usually fragile and brittle with poor interfacial contact with electrodes . In contrast, the polymer electrolyte exhibits several merits such as good compatibility with the electrode, mechanical flexibility, improved processibility for large-scale manufacturing, and easy-to-deform characteristic for emerging applications .…”

Mesoporous carbons from self‐assembled polymers

“…Producing aligned pores in MCs is highly desired for multiple applications especially those demanding fast and unidirectional diffusion of guest molecular species within pore channels, primarily due to two advantages. 40 First, alignment of nanodomains can minimize the tortuosity of diffusion pathways, facilitating the transport of species and enabling faster sorption/diffusion kinetics. Additionally, MCs with unidirectional nanostructures can exhibit enhanced material properties along the alignment direction compared to their random-oriented analogues.…”

“…As a canonical system, surfactants and/or block copolymers (BCP) can spontaneously generate periodic nanostructures due to the incompatibility between their covalently linked, chemically distinct segments, while providing precise control over the resulting pattern size and morphology through manipulating the chemical composition and physical properties. [39][40][41][42] In MC systems, these nanostructures consist of sacrificial segments in the minority phase which can be thermally decomposed to produce pores, and carbon precursors in the majority phase which produces high degrees of carbon yield upon exposure to temperatures above 600 C in inert atmospheres. For example, the conversion of resol and polyacrylonitrile to carbon upon pyrolysis have been investigated by many studies.…”

A Polymer Electrolyte with High Cationic Transport Number for Safe and Stable Solid Li-Metal Batteries

“…The rapid popularization of consumer electronics and electric vehicles, along with the integration of renewable energy sources into the grid, has generated a high demand for energy storage technologies with superior electrochemical performance, including energy density and cycle/calendar life as well as efficiency. − The solid-state lithium (Li) metal battery (LMB) promises the highest energy densities (Li-metal anode, bipolar stacking design) and improved safety (no liquid leakage, fewer fire hazards); − however, such promises still face various scientific and technological barriers. Among different types of solid electrolytes, a polymer electrolyte (PE) offers the unique benefits of compliant interfacial contact with solid electrodes, better processability for large-scale manufacturing, and mechanical flexibility to allow nontraditional form factors that are critical for the emerging applications. − Recently, with a thick solid electrolyte (∼800 μm) or addition of a spacer (to avoid short circuit), some PEO-based PEs have also been reported to enable a high-voltage cathode lithium-metal battery with reasonable cycling performance. − These benefits, again, cannot be accessed unless effective ion transport is achieved. Most PEs consist of a lithium salt dissolved in macromolecular solvents (i.e., a polymer chain); hence, both cations and anions can move. , While the participation of both ions in transport indeed makes the ionic conductivity higher, at a current density above a respective threshold, the transport of inactive anions will cause severe concentration polarization in the cell, which prevents battery operation at high rates. − A polymer electrolyte with a high cationic transport number ( t Li + ), normally a single-ion conducting polymer electrolyte (SIPE), in which anions do not move, could theoretically address these challenges.…”