Transition mechanisms of three-dimensional nanostructures formed from geometrically constraining (AB)f star block copolymers

• Published in: Polymer (Guilford) Vol. 177; pp. 202 - 207
• Main Authors: Shao, Zhanwei, Zhang, Di, Hu, Weiguo, Xu, Yuci, Li, Weihua
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 26.08.2019; Elsevier BV
• Subjects: Block copolymer; Block copolymers; Confinement; Copolymers; Cylindrical confinement; Field theory; Nanostructure; Phase diagrams; Phase transition sequence; Phase transitions; Pore size; Porosity; Self consistent fields; Self-assembly; Star-like; Star-like; Cylindrical confinement; Phase transition sequence; Block copolymer
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2019.05.062

The self-assembly behavior of (AB)f star copolymers under a cylindrical confinement has been investigated using self-consistent field theory. Aiming to study the influence of the pore diameter on the order-order transitions as volume fraction varies, the phase diagram with respect to the volume fraction and the pore size is constructed. An interesting transition sequence of ordered nanostructures, H2A→P2A→L2A→ P3CB→H3CB, is predicted, which is corresponding to the phase transition of C→ G→L→G→C in bulk. Notably, this transition sequence is universal for both linear (AB diblock and BAB triblock) and star-like (AB)f block copolymer. In particular, we explore the formation mechanism of helical nanostructures as the volume fraction increases, where the P phase plays an important role in forming helical structures as an intermediate nanostructure. Finally, we construct the two-dimensional phase diagram, including pore size and volume fraction, of (AB)f star-like block under confinement at different number of arms, where P nanostructures was found to surrounded by other nanophases suggesting the importance of P nanostructure in the transition sequence. We, for the first time, identified the volume fraction independent phase transition sequence under cylindrical confinement at the full volume fraction space, that is, H1A→P2A→L2A→ P3CB→H3CB, which is corresponding to the phase transition of C→ G→L→G→C in bulk. This transition sequence is universal for both linear (AB diblock and BAB triblock) and star-like (AB)f diblock copolymer. The explored phase transition sequence under confinement is helpful to understand the transition mechanism of these nanostructures. [Display omitted] •We explored a new phase transition sequence (H1A.→P2A→L2A→P3CB→H3CB) under cylindrical confinement.•P nanostructures play a crucial role to the formation of helical structures.•The obtained transition sequence is universal for both linear and star like block architectures.