Dataset Information

Molecular Dynamics of Janus Nanodimers Dispersed in Lamellar Phases of a Block Copolymer.

ABSTRACT: We investigate structural and dynamical properties of Janus nanodimers (NDs) dispersed in lamellar phases of a diblock copolymer. By performing molecular dynamics simulations, we show that an accurate tuning of the interactions between NDs and copolymer blocks can lead to a close control of NDs' space distribution and orientation. In particular, NDs are preferentially found within the lamellae if enthalpy-driven forces offset their entropic counterpart. By contrast, when enthalpy-driven forces are not significant, the distribution of NDs, preferentially observed within the inter-lamellar spacing, is mostly driven by excluded-volume effects. Not only does the degree of affinity between host and guest species drive the NDs' distribution in the polymer matrix, but it also determines their space orientation. In turn, these key structural properties influence the long-time dynamics and the ability of NDs to diffuse through the polymer matrix.

SUBMITTER: Burgos-Marmol JJ

PROVIDER: S-EPMC8126030 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature

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Molecular Dynamics of Janus Nanodimers Dispersed in Lamellar Phases of a Block Copolymer.

Burgos-Mármol J Javier JJ Patti Alessandro A

Polymers 20210509 9

We investigate structural and dynamical properties of Janus nanodimers (NDs) dispersed in lamellar phases of a diblock copolymer. By performing molecular dynamics simulations, we show that an accurate tuning of the interactions between NDs and copolymer blocks can lead to a close control of NDs' space distribution and orientation. In particular, NDs are preferentially found within the lamellae if enthalpy-driven forces offset their entropic counterpart. By contrast, when enthalpy-driven forces a ...[more]

PMID: 34065148

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Project description:Designing next-generation lightweight pulsed power devices hinges on understanding the factors influencing the energy storage performance of dielectric materials. Polymer dielectric films have a quadratic dependence of energy storage on the voltage breakdown strength, and strategies to enhance the breakdown strength are expected to yield a path toward high energy storage densities. Highly stratified lamellar block copolymer (L-BCP) films of model polystyrene-b-polymethylmethacrylate (PS-b-PMMA) exhibited as much as ~50% enhancement in breakdown voltage ( EBD ) (225% increase in stored energy density, U∼EBD2 ) compared to unordered as-cast L-BCP films. Such an energy density using amorphous polymer is on par with industry-standard semicrystalline biaxially oriented polypropylene (BOPP) and as such a notable development in the field. This work develops a deeper understanding of the molecular mechanisms of EBD enhancement in L-BCP films, relating EBD directly to molecular weight ( Mn ), with interpretation to effects of chain-end density and distribution, interface formation, layer thickness, and their relative contributions. As-cast disordered L-BCP films show decreasing EBD with decreasing Mn similar to homopolymer studies because of the increase of homogeneously distributed chain ends in the film. EBD increases significantly in parallel ordered L-BCP films because of the combination of interface formation and spatial isolation of the chain ends into segregated zones. We further confirm the role of chain ends in the breakdown process blending a low Mn L-BCP with matched Mn homopolymers to attain the same layer spacing as neat L-BCP of higher Mn . EBD shows a significant decrease at low homopolymer fractions because of increased net chain-end density within swollen ordered L-BCP domains in wet-brush regime, followed by increased EBD because of layer thickness increase via segregated "interphase layer" formation by excess homopolymers. Notably, EBD of homopolymer swollen L-BCPs is always lower than that of neat L-BCPs of the same domain spacing because of overall adverse chain-end contribution from homopolymers. These findings provide important selection rules for L-BCPs for designing next-generation flexible electronics with high energy density solid-state BCP film capacitors.

Dataset Information

Molecular Dynamics of Janus Nanodimers Dispersed in Lamellar Phases of a Block Copolymer.

Publications

Molecular Dynamics of Janus Nanodimers Dispersed in Lamellar Phases of a Block Copolymer.

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