# Architecture Effect on Network Phase Formation from Controlled Self-Assembly of High‑χ Block Copolymers

## TL;DR

This paper explores how the architecture of block copolymers affects their self-assembly into complex network phases.

## Contribution

The study demonstrates that star-shaped block copolymers can form diverse network phases more easily than linear ones.

## Key findings

- Star-shaped block copolymers form network phases with complex topologies like double gyroid and Frank–Kasper-like structures.
- Controlled self-assembly via solvent evaporation enables the formation of network phases with alternating strut nodes.
- The architecture effect reduces packing frustration, enabling richer phase behaviors in high-χ block copolymers.

## Abstract

This work aims to examine the architecture effect on
the self-assembly
of high-χ block copolymers (BCPs), polystyrene-block-polydimethylsiloxane (PS-b-PDMS). Lamellae-forming
diblock and star BCPs with three and six arms were synthesized for
self-assembly. A variety of self-assembled phases, especially network
phases, can be formed by tuning the solvent evaporation rate for solution
casting using PS-selective solvents (referred to as controlled self-assembly).
In contrast to diblocks with linear architecture, the formation of
network phases from star BCPs can be easily acquired via controlled
self-assembly. It is possible to enrich the topological features of
the forming network phases, giving double gyroid and Frank–Kasper-like
network phases, with alternating three- and four-strut nodes, as well
as a double diamond phase due to the alleviation of packing frustration
from network formation. As a result, the architecture effect on the
phase behaviors of high-χ BCPs via controlled self-assembly
gives easy access to acquire a variety of network phases.