Orthorhombic Fddd Network in Diblock Copolymer Melts

TL;DR

This paper reports the first experimental observation of an Fddd network structure in diblock copolymer melts, confirming theoretical predictions and expanding understanding of phase behavior in these materials.

Contribution

It provides the first experimental evidence of the Fddd network in S-I diblock copolymer melts, validating previous theoretical models.

Findings

Fddd network observed in S-I diblock copolymer melts

Phase diagram shows Disorder- Fddd-Lamellae sequence

Unit cell ratios match theoretical calculations

Abstract

For the first time a Fddd network structure is found in a poly(styrene-b-isoprene) (S-I) diblock copolymer melts by using small-angle X-ray scattering and transmission electron microscope, as predicted by Tyler et al. by using calculations with self-consistent field theory for diblock copolymer melts. The phase diagram of the S-I exhibits the sequence of Disorder- Fddd-Lamellae with decreasing temperature. The measured unit cell parameters ratios (a,b,c) are (1:2.02:3.46), which agrees with the result of the theoretical calculation.