Volume 98, 1994

Fluctuations, conformational asymmetry and block copolymer phase behaviour

Abstract

Phase behaviour near the order–disorder transition (ODT) of 58 model hydrocarbon diblock copolymers, representing four different systems, is summarized. Six distinct ordered-state microstructures are reported, including hexagonally modulated lamellae (HML), hexagonally perforated layers (HPL) and a bicontinuous cubic morphology with Ia3d space group symmetry. Two non-classical parameters, ε and N, control the occurrence and distribution of these phases, in addition to the classical variables ƒ and χN, where ƒ, χ and N are the composition, segment–segment interaction parameter and degree of polymerization, respectively. ε accounts for differences in the conformational and volume-filling characteristics of each block. Conformational asymmetry, ε≠ 1, produces an asymmetric phase diagram around ƒ= 1/2. The importance of fluctuation effects are inversely related to the magnitude of N, a type of Ginzburg parameter that is proportional to N. As N decreases, the bicontinuous Ia3d phase appears adjacent to the ODT. Development of this cubic phase can be rationalized based on chain-packing frustration near the lamellar hexagonal state. Apparently the Ia3d cubic state is stabilized by fluctuations since it disappears when N becomes large. These findings provide new insights into the origins of phase complexity in condensed soft matter.

Article information

Article type
Paper

Faraday Discuss., 1994,98, 7-18

Fluctuations, conformational asymmetry and block copolymer phase behaviour

F. S. Bates, M. F. Schulz, A. K. Khandpur, S. Förster, J. H. Rosedale, K. Almdal and K. Mortensen, Faraday Discuss., 1994, 98, 7 DOI: 10.1039/FD9949800007

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements