Using Grazing-Incidence Small-Angle Neutron Scattering to Study the Orientation of Block Copolymer Morphologies in Thin Films

Hu, Mingqiu; Li, Xindi; Heller, William T.; Bras, Wim; Rzayev, Javid; Russell, Thomas P.

doi:10.1021/acs.macromol.2c02415

Cited by 6 publications

(3 citation statements)

References 94 publications

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“…Future investigation using grazing-incidence small angle neutron scattering (GISANS) is needed to characterize the in-plane ordering. 50…”

Section: Resultsmentioning

confidence: 99%

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Janus bottlebrush compatibilizers

Chen,

Seong,

et al. 2024

Soft Matter

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“…Future investigation using grazing-incidence small angle neutron scattering (GISANS) is needed to characterize the in-plane ordering. 50…”

Section: Resultsmentioning

confidence: 99%

“…Future investigation using grazingincidence small angle neutron scattering (GISANS) is needed to characterize the in-plane ordering. 50 The segmental density distribution profile allows us to calculate surface excess (G) for each block using…”

Section: Segmental Density Distributionmentioning

confidence: 99%

Janus bottlebrush compatibilizers

Chen,

Seong,

et al. 2024

Soft Matter

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“…The result was further confirmed by the absence of the out-of-plane peak from grazing-incidence small-angle neutron scattering (GISANS) on the same sample (Figure S13). The indiscernible in-plane peaks also suggested that the intermolecular spacing between these s-BCPs at the interface is poorly defined, which potentially originates from the inherent softness of these s-BCPs. This hypothesis is supported by the presence of prominent in-plane peaks when same s-BCPs become much more rigid when P2VP blocks carry charge at the fluid interface …”

Section: Results and Discussionmentioning

confidence: 99%

Star Block Copolymers at Homopolymer Interfaces: Conformation and Compatibilization

Chen,

Steinmetz,

et al. 2023

Macromolecules

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Star block copolymers (s-BCPs), comprised of multiple linear diblock copolymers joined at a central point, are shown to segregate to the interface between two immiscible homopolymers that are identical to the blocks of the s-BCPs. The s-BCPs undergo a configurational transition at the interface, with different blocks of copolymers being embedded in their respective homopolymers, thereby bridging the interface and promoting adhesion. A series of 4-arm s-BCPs were synthesized with hydrogenated or deuterated polystyrene (PS/dPS) as the core block and poly(2-vinylpyridine) (P2VP) as the corona block, which was directly placed at the interface between the two homopolymers. Neutron reflectivity (NR) was used to determine the concentration profiles of the PS homopolymer, s-BCP core blocks, and P2VP total segments under equilibrium. The investigation varies the molecular weight (MW) and the total number of s-BCPs at the interface. Self-consistent-field theory (SCFT) was also employed to calculate the concentration profiles of the components at the interface, which were in excellent agreement with experimental results. The NR showed that the interfacial width between the homopolymers increased with the increasing number of s-BCPs at the interface up to a saturation limit. Beyond this limit, additional s-BCPs were released into the corona-miscible phase as unimolecular micelles. For a comparable interlayer thickness of s-BCPs at the interface, lower MW s-BCPs generated a broader interface. SCFT analysis suggested that, at the same packing density, the arms of the low MW s-BCPs align more parallel to the interface, while the arms of high MW s-BCPs adopt a more normal orientation, like their linear BCP counterparts. Furthermore, it was also observed that the core blocks, constrained by the junction points, were oriented more parallel and closer to the interface than the corona blocks. The phase behavior of the polymer blends revealed that s-BCP additives can efficiently reduce the domain size, with the low MW yielding smaller domain sizes due to the greater reduction in the interfacial energy and the high MW arresting phase separation due to their higher binding energy and a jamming of the interfacial assemblies. Asymmetric double cantilever beam (ADCB) tests demonstrated that s-BCPs promoted adhesion more efficiently than their linear BCP counterparts due to stronger binding energy per molecule, suggesting a more efficient compatibilizer for polymer upcycling. The results from these studies provide fundamental insights into the assembly of s-BCPs at homopolymer interfaces, the reduction of domain size, and promotion of adhesion, providing a strategy for the use of s-BCPs as stealth surfactants and universal compatibilizers.

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Phase Behavior of Charged Star Block Copolymers at Fluids Interface

Chen,

Ribbe,

Steinmetz

et al. 2024

Angewandte Chemie

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The phase behaviors of block copolymers (BCPs) at the water‐oil interface are influenced by the segmental interaction parameter (χ) and chain architecture. We synthesized a series of star block copolymers (s‐BCPs) having polystyrene (PS) as core and poly(2‐vinylpyridine) (P2VP) as corona. The interaction parameters of block‐block (χPS‐P2VP) and block‐solvent (χP2VP‐solvent) were varied by adjusting the pH of the aqueous solution. Lowering pH increased the fraction of quaternized‐P2VP (Q‐P2VP) with enhanced hydrophilicity. By transferring the equilibrated interfacial assemblies, morphologies ranging from bicontinuous films at pH of 7 and 3.1 to nanoporous and nanotubular structure at pH of 0.65 were observed. The nanoporous films formed hexagonally packed pores in s‐BCP matrix, while nanotubes comprised Q‐P2VP as corona and PS as core. Control over pore size, d‐spacing between pores, and nanotube diameters was achieved by varying polymer concentration, molecular weight, volume fraction and arm number of s‐BCPs. Large‐scale nanoporous films were obtained by freeze‐drying emulsions. Remarkably, the morphologies of linear BCPs were inverted, forming hexagonal‐packed rigid spherical micelles with Q‐P2VP as core and PS as corona in multilayer. This work provides insights of phase behaviors of BCP at fluids interface and offer a facile approach to prepare nanoporous film with well‐controlled pore structure.

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Using Grazing-Incidence Small-Angle Neutron Scattering to Study the Orientation of Block Copolymer Morphologies in Thin Films

Cited by 6 publications

References 94 publications

Janus bottlebrush compatibilizers

Janus bottlebrush compatibilizers

Star Block Copolymers at Homopolymer Interfaces: Conformation and Compatibilization

Phase Behavior of Charged Star Block Copolymers at Fluids Interface

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