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Effects of Spacers on Photoinduced Reversible Solid‐to‐Liquid Transitions of Azobenzene‐Containing Polymers
Author(s) -
Weis Philipp,
Hess Andreas,
Kircher Gunnar,
Huang Shilin,
Auernhammer Günter K.,
Koynov Kaloian,
Butt HansJürgen,
Wu Si
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902273
Subject(s) - photoisomerization , azobenzene , materials science , polymer , photochemistry , methylene , isomerization , chemistry , organic chemistry , composite material , catalysis
Photoisomerization in some azobenzene‐containing polymers (azopolymers) results in reversible solid‐to‐liquid transitions because trans ‐ and cis ‐azopolymers have different glass transition temperatures. This property enables photoinduced healing and processing of azopolymers with high spatiotemporal resolution. However, a general lack of knowledge about the influence of the polymer structure on photoinduced reversible solid‐to‐liquid transitions hinders the design of such novel polymers. Herein, the synthesis and photoresponsive behavior of new azopolymers with different lengths of spacers between the polymer backbone and the azobenzene group on the side chain are reported. Azopolymers with no and 20 methylene spacers did not show photoinduced solid‐to‐liquid transitions. Azopolymers with 6 or 12 methylene spacers showed photoinduced solid‐to‐liquid transitions. This study demonstrates that spacers are essential for azopolymers with photoinduced reversible solid‐to‐liquid transitions, and thus, gives an insight into how to design azopolymers for photoinduced healing and processing.