A Neutron Reflectivity Study on a Terraced Lamellar Morphology in a Block Copolymer Thin Film

Niihara, Ken Ichi; Matsuwaki, Ukyo; Torikai, Naoya; Satoh, Kotaro; Kamigaito, Masami; Jinnai, Hiroshi

doi:10.1295/polymj.pj2007100

Cited by 3 publications

(1 citation statement)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The one-step height almost agrees with the layered lamellar domain spacing of their two copolymers determined by NR, meaning that the sub-5 nm multilayered lamellar structures were directly observed as terrace structures by the AFM. 62,63 In contrast, such terrace structures were not observed for the as-cast samples of P4 and P8. These results also support that humidity is a key factor to promote the microphase separation of their pendants.…”

Section: ■ Introductionmentioning

confidence: 82%

Water-Assisted Microphase Separation of Cationic Random Copolymers into Sub-5 nm Lamellar Materials and Thin Films

et al. 2022

View full text Add to dashboard Cite

Microphase separation of copolymers is a key technique to produce polymer bulk materials or thin films with ordered nanostructures for applications in various research fields including nanotechnologies, electronic devices, among many others. Herein, we report water-assisted microphase separation of amphiphilic random copolymers bearing quaternary ammonium cations and hydrophobic alkyl or oleyl groups in the solid state and the thin films. We investigated the effects of sample preparation protocols and the hydrophobic pendants (a butyl group: C4 − octadecyl or oleyl group: C18), composition, and molecular weight of the copolymers on the microphase separation behavior. By annealing under humid conditions, the copolymers bearing alkyl groups longer than an octyl group (C8) formed sub-5 nm lamellar structures comprising cationic layers and hydrophobic layers. Water hardly remained in the resulting lamellar materials under ambient conditions. The domain spacing was controlled between 3.7 and 5.3 nm by tuning the length of the hydrophobic pendants and composition and was independent of the molecular weight and molecular weight distribution. The cationic random copolymers carrying amorphous hydrophobic pendants provided transparent or translucent polymer materials containing small lamellar structures. The random copolymers further formed multilayered lamellar thin films on silicon substrates by spin-coating the copolymer solutions, followed by a humid annealing process. The layered lamellae were directly observed as terrace structures with about 4–5 nm steps by atomic force microscopy.

show abstract

Section: ■ Introductionmentioning

confidence: 82%

Water-Assisted Microphase Separation of Cationic Random Copolymers into Sub-5 nm Lamellar Materials and Thin Films

et al. 2022

View full text Add to dashboard Cite

show abstract

Dynamics of interacting edge defects in copolymer lamellae

et al. 2011

View full text Add to dashboard Cite

It is known that terraces at the air-polymer interface of lamella-forming diblock copolymers do not make discontinuous jumps in height. Despite the underlying discretized structure, the height profiles are smoothly varying. The width of a transition region of a terrace edge in isolation is typically several hundreds of nanometres, resulting from a balance between surface tension, chain stretching penalties, and the enthalpy of mixing. What is less well known in these systems is what happens when two transition regions interact with one another. In this study, we investigate the dynamics of the interactions between copolymer lamellar edges. We find that the data can be well described by a model that assumes a repulsion between adjacent edges. While the model is simplistic, and does not include molecular level details, its agreement with the data suggests that some of the the underlying assumptions provide insight into the complex interplay between defects.

show abstract