Monitoring morphology evolution within block copolymer microparticles during dispersion polymerisation in supercritical carbon dioxide: a high pressure SAXS study
Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerisation in supercritical carbon dioxide is an effective process for creating block copolymer microparticles with internal nanostructures. Here we report an alternative synthesis route involving completely independent steps by...
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Veröffentlicht in: | Polymer chemistry 2019-01, Vol.10 (7), p.860-871 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerisation in supercritical carbon dioxide is an effective process for creating block copolymer microparticles with internal nanostructures. Here we report an alternative synthesis route involving completely independent steps by exploiting the livingness of RAFT-terminated PMMA microparticles and their unique ability to be redispersed in scCO
2
. This not only enables a series of block copolymers to be created from a single RAFT dispersion synthesised PMMA homopolymer batch, thus improving reproducibility, but also adds flexibility by allowing the time and concentration requirements for each stage to be decoupled. The internal morphology development and evolution for a series of poly(methyl methacrylate-
block
-styrene) (PMMA-
b
-PS) block copolymer microparticles synthesised
via
this route was monitored
via in situ
small-angle X-ray scattering (SAXS) using an autoclave with diamond windows. Together with offline kinetics experiments and post-mortem transmission electron microscopy imaging, this study provides remarkably detailed insights into block copolymer self-organisation phenomena in scCO
2
. Specifically, the time period over which this block copolymer undergoes phase separation before progressing from an arrangement of spheres to lamellae
via
the hexagonal cylinder phase is elucidated, and the data are used to plot a detailed empirical phase diagram for this block copolymer system in scCO
2
. |
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ISSN: | 1759-9954 1759-9962 |
DOI: | 10.1039/C8PY01578C |