Using tapered interfaces to manipulate nanoscale morphologies in ion-doped block polymers

Kuan, Wei‐Fan; Reed, Ellen H.; Nguyen, Ngoc A.; Mackay, Michael E.; Epps, Thomas H.

doi:10.1557/mrc.2015.19

Cited by 19 publications

(55 citation statements)

References 30 publications

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“…Recently, the Epps group has focused on the incorporation of graded polymer profiles between the homogeneous copolymer blocks (i.e. tapers) and lithium salts as dopants to control morphology, glass transition temperature (T g ), order‐disorder transition temperature (T ODT ), and other key attributes of macromolecular self‐assembly . By combining both gradient interfaces and additives, uniquely tailored materials with improved properties and performance can be created to advance new technologies or augment existing ones.…”

Section: Bulk Polymer Interfacial Modifications In Self‐assembled Sysmentioning

confidence: 99%

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Tuning Block Polymer Structure, Properties, and Processability for the Design of Efficient Nanostructured Materials Systems

Morris

Gartner

Epps

2017

Macro Chemistry & Physics

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Block polymers (BPs) are ideal building blocks for nanoporous membranes, microelectronics templates, energy storage devices, and other technologies. For these systems, precise control over morphology, properties, and processability are essential to optimize performance. The Epps group has used a multidisciplinary approach to control BP nanostructure ordering and orientations, order-disorder and glass transition temperatures, and mechanical and transport properties through the informed manipulation of BP effective segregation strengths and interfacial energetics. For example, alterations in macromolecular interactions between BP chains were achieved through the introduction of composition gradients between copolymer blocks or by adding dopants. In thin films, high-throughput approaches were designed to modify and characterize substrate-polymer interactions, and solvent annealing techniques were developed to facilitate nanoscale alignment and ordering. By manipulating BP interfacial energetics to gain exquisite tunability of nanostructures and materials' properties, the group is accelerating the development of next-generation BPs that will be harnessed to fabricate inexpensive, efficient, and high-performance devices.

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Section: Bulk Polymer Interfacial Modifications In Self‐assembled Sysmentioning

confidence: 99%

“…The effect of salt concentration on morphology in PS‐POEM BPs and TBPs was examined by comparing the diblock to copolymers containing a normal or inverse taper ( f taper = 0.60) . All BPs were made with f POEM = 0.52 and doped with LiCF 3 SO 3 (lithium triflate).…”

Section: Bulk Polymer Interfacial Modifications In Self‐assembled Sysmentioning

confidence: 99%

Tuning Block Polymer Structure, Properties, and Processability for the Design of Efficient Nanostructured Materials Systems

Morris

Gartner

Epps

2017

Macro Chemistry & Physics

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“…We do not consider the hexagonally packed cylinder phase here, which may be the preferred phase for systems at high χN in Figure 3a, due to asymmetry at low ion content. 31,83,84 Increasing either S A± or l B widens the coexistence region; the effect of solvation appears to be larger.…”

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confidence: 92%

“…[24][25][26] Salt may also be added to copolymers to tune the degree of phase segregation or change microphase morphology (without changing temperature or polymer chemistry), which is of both practical and scientific interest. 16,[27][28][29][30][31] Neat AB diblock copolymers microphase separate into various ordered structures; morphology depends primarily on composition (quantified by f A , the fraction of "A" monomers), and segregation strength χN , where χ is the Flory parameter which quantifies chemical incompatibility of the two components and N is the degree of polymerization. 32,33 Salt dissolves predominantly in one microphase, primarily due to the different dielectric constants (less energy is required to place an ion in a medium of higher dielectric constant, as described by the ion's Born energy).…”

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confidence: 99%

Ion Correlation Effects in Salt-Doped Block Copolymers

2018

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We apply classical density functional theory to study how salt changes the microphase morphology of diblock copolymers. Polymers are freely jointed and one monomer type favorably interacts with ions, to account for the selective solvation that arises from different dielectric constants of the microphases. By including correlations from liquid state theory of an unbound reference fluid, the theory can treat chain behavior, microphase separation, ion correlations, and preferential solvation, at the same coarse-grained level. We show good agreement with molecular dynamics simulations.

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“…26 One way tapered copolymers can be formed experimentally is via a semi-batch process of many sequential living anionic polymerization steps; during each step the two different types of monomers are injected in different amounts and are polymerized approximately randomly. 4,5,16,[27][28][29][30][31][32] A very recent work showed an excellent agreement between tapered copolymer density profiles from experiment and fDFT (with a fixed sequence), 17 though comparisons between experiment and theory with respect to order-disorder transitions or dynamics have not been as specific and precise.…”

Section: Introductionmentioning

confidence: 99%

Effect of sequence dispersity on morphology of tapered diblock copolymers from molecular dynamics simulations

Levine

Seo

Brown

et al. 2016

The Journal of Chemical Physics

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Tapered diblock copolymers are similar to typical AB diblock copolymers but have an added transition region between the two blocks which changes gradually in composition from pure A to pure B. This tapered region can be varied from 0% (true diblock) to 100% (gradient copolymer) of the polymer length, and this allows some control over the microphase separated domain spacing and other material properties. We perform molecular dynamics simulations of linearly tapered block copolymers with tapers of various lengths, initialized from fluids density functional theory predictions. To investigate the effect of sequence dispersity, we compare systems composed of identical polymers, whose taper has a fixed sequence that most closely approximates a linear gradient, with sequentially disperse polymers, whose sequences are created statistically to yield the appropriate ensemble average linear gradient. Especially at high segregation strength, we find clear differences in polymer conformations and microstructures between these systems. Importantly, the statistical polymers are able to find more favorable conformations given their sequence, for instance, a statistical polymer with a larger fraction of A than the median will tend towards the A lamellae. The conformations of the statistically different polymers can thus be less stretched, and these systems have higher overall density. Consequently, the lamellae formed by statistical polymers have smaller domain spacing with sharper interfaces. Published by AIP Publishing. [http://dx

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Using tapered interfaces to manipulate nanoscale morphologies in ion-doped block polymers

Abstract: Abstract

Cited by 19 publications

References 30 publications

Tuning Block Polymer Structure, Properties, and Processability for the Design of Efficient Nanostructured Materials Systems

Tuning Block Polymer Structure, Properties, and Processability for the Design of Efficient Nanostructured Materials Systems

Ion Correlation Effects in Salt-Doped Block Copolymers

Effect of sequence dispersity on morphology of tapered diblock copolymers from molecular dynamics simulations

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