Self-assembly of a silicon-containing side-chain liquid crystalline block copolymer in bulk and in thin films: kinetic pathway of a cylinder to sphere transition

Liao, Fen‐Ling; Shi, Linying; Cheng, Li‐Chen; Lee, Sangho; Ran, Rong; Yager, Kevin G.; Ross, Caroline A.

doi:10.1039/c8nr07685e

Cited by 20 publications

(19 citation statements)

References 53 publications

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“…LCBCPs with a small volume fraction of amorphous block (f a ) tend to form a spherical phase in a BCC lattice-f a = 0.18 for the same LCBCP with Az ( 46) and f a = 0.27 for different LCBCP system (47)-beyond their T iso . In the cooling process, at its T iso , the phase transition from spherical to cylindrical is induced by liquid crystallization (46,47) . It is thus an interesting question of when the macro-phase segregation and multilayerization take place in blended LCBCP systems, which may also answer the question of why LCBCP blends have higher immiscibility than homopolymer blends (S 60 &A 55 ), as revealed via the XPS experiments.…”

Section: Resultsmentioning

confidence: 99%

Self-template–assisted micro-phase segregation in blended liquid-crystalline block copolymers films toward three-dimensional structures

Hibi

Oguchi

Shimizu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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In-plane mesopatterns derived from block-copolymer (BCP) micro-phase segregation in thin films have attracted much interest in practical applications as well as fundamental research programs. However, phase segregation along the film-normal direction has been less studied. Here, we describe a strategy to concurrently, yet independently, control in-plane micro-phase and out-of-plane macro-phase segregation in multiblended films composed of liquid-crystalline BCPs (LCBCPs), affording spontaneously layered three-dimensional (3D) mesostructures. This strategy relies on sequential liquid crystallization during the cooling process in thermal annealing as follows. The constituent LCBCP with the highest isotropic-transition temperature (Tiso) first liquid-crystallizes and segregates from the other LCBCP mixture remaining in isotropic states to form a noncontaminated layer at the top surface. This preformed LCBCP layer preserves its inherent in-plane pattern and acts as a template guiding the subsequent micro-phase segregations of the other low-Tiso LCBCPs underneath. This self-template–assisted micro-phase segregation (STAMPS) readily provides 3D mesostructures, the potential toward rational material design of which is also demonstrated in water-separation applications.

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Section: Resultsmentioning

confidence: 99%

Self-template–assisted micro-phase segregation in blended liquid-crystalline block copolymers films toward three-dimensional structures

Hibi

Oguchi

Shimizu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Si‐containing systems, such as polydimethylsiloxane (PDMS)‐containing BCPs, are of particular interest, since the PDMS domains can be directly converted to silica through a simple step of reactive ion etching or ultraviolet–ozone treatment 29–33 . While such strategies are effective for producing functional nanopatterns, complex and sophisticated preparations of high‐ χ BCPs are typically required in these systems, often involving multiple steps of monomer synthesis and post‐polymerization functionalization 34,35 …”

Section: Introductionmentioning

confidence: 99%

A simple route to prepare supramolecular block copolymers using telechelic polystyrene/polydimethylsiloxane pairs

Obando

Chen

Qiang

2021

Polymer International

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While supramolecular block copolymer (BCP) self‐assembly has been widely studied over the past decades as an effective means to generate functional nanomaterials, most of these systems require multiple steps of synthesis and processing. In this report, we introduce a facile approach to form linear multiblock copolymers by directly blending telechelic homopolymer pairs, using di‐sulfonated polystyrene and commercially available, aminopropyl terminated polydimethylsiloxane. A series of model multiblock copolymers were prepared, in which proton transfers between polymer chain ends enable the formation of strong ionic associations. These ionic junctions not only significantly enhance thin film stability of polymer blends by forming higher molecular weight copolymers, but also improve the chemical incompatibility between different segments, resulting in ordered nanostructures upon self‐assembly. These include different morphologies such as lamellae and cylinders. We also demonstrate that feature size of these BCPs can be adjusted by varying the molecular weight of the homopolymers, with a smallest domain spacing of approximately 12.9 nm being obtained. Utilizing low‐cost and widely available polymers as building blocks, our simple and efficient supramolecular assembly strategy for forming multiblock copolymers may provide a promising platform for cost‐efficient nanomanufacturing of polymeric materials. © 2021 Society of Industrial Chemistry.

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“…The research on polymers with liquid crystalline (LC) pendants has emerged as one of the major topics in materials science. [1][2][3][4][5][6][7][8] The combination of BCP topology and LCs is expected to allow for the design of advanced features in functional materials, allowing thus miniaturization of domain spacing in nanoscopic materials, high processability and the designing of novel morphologies. [9][10][11][12] In addition, the introduction of chiral functionality to LCPs has become one of the most important topics in LC research as it may permit the introduction of chiral nanostructures due to chiral amplification.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers

Velmurugan

Chen

et al. 2020

Macromolecules

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Block copolymers (BCPs) comprising of a poly(methyl methacrylate) (PMMA) block and a poly(cholesteryloxyhexyl methacrylate block (PChMA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The self-assembly of the liquid crystalline block copolymers was characterized by differential scanning calorimetry (DSC), 1 polarized optical microscopy (POM) and synchrotron-based small-angle X-ray scattering (SAXS). The results indicate the formation of both tilted and non-tilted chiral smectic (SmC* and SmA*) phases. A phase transition from SmA* to SmC* phase on cooling was observed for BCPs, but not for PChMA homopolymers. The layer spacing (5.00 ± 0.18 nm) between those can be controlled to maintain the number of ChMA units whilst varying the lengths of the PMMA block, introducing thus systematically the SmC* phase. Furthermore, BCPs with short PMMA block showed inversion of chirality at specific temperatures; while for PChMA attached with long PMMA block no chirality inversion was observed. This mode of chirality switching, investigated by CD, NMR, and theoretical studies, is associated with the methyl substituents in the backbone affecting the packing of the polymers. The basic rules, described here, have the potential to be implemented for the design of a wide range of functional materials where helix-helix conversion is of use. helix-helix transitions in nature and has the potential to be exploited further for artificial systems. ASSOCIATED CONTENT Supporting InformationExperimental methods, NMR, DSC, POM, SAXS, WAXS, CD and theoretical calculation results are included in the supporting information.

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Self-assembly of a silicon-containing side-chain liquid crystalline block copolymer in bulk and in thin films: kinetic pathway of a cylinder to sphere transition

Abstract: Hierarchical morphologies and transitions of a silicon-containing LCBCP were investigated and the kinetic transition from HEX to BCC is described.

Cited by 20 publications

References 53 publications

Self-template–assisted micro-phase segregation in blended liquid-crystalline block copolymers films toward three-dimensional structures

Self-template–assisted micro-phase segregation in blended liquid-crystalline block copolymers films toward three-dimensional structures

A simple route to prepare supramolecular block copolymers using telechelic polystyrene/polydimethylsiloxane pairs

Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers

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