Premium
Light controlled solubility change of polymers: Copolymers of N , N ‐dimethylacrylamide and 4‐phenylazophenyl acrylate
Author(s) -
Kröger Rainer,
Menzel Henning,
Hallensleben Manfred L.
Publication year - 1994
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1994.021950701
Subject(s) - lower critical solution temperature , azobenzene , copolymer , polymer chemistry , photoisomerization , acrylate , polymer , chemistry , materials science , isomerization , organic chemistry , catalysis
Copolymers of N , N ‐dimethylacrylamide (DMA) and 4‐phenylazophenyl acrylate (PAPA) have been prepared by free‐radical copolymerization in dioxane (DMAP‐ x ). The molecular weights of the copolymers show a strong decrease with increasing azobenzene content due to the retardation effect of the azobenzene group. An analogous decrease in molecular weight was found with a number of polymers of DMA which were polymerized in the presence of the non‐polymerizable model 4‐phenylazophenyl propionate (PAPP). We were able to induce a lower critical solution temperature (LCST) above a certain content of azobenzene moieties in the copolymers (DMAP‐ x ) in contrast to the good water solubility of poly(DMA). Due to the reversible photoisomerization and the concomitant change in the dipole moment of the azobenzene moieties, the LCST depends not only on the content of azobenzene but also on the degree of isomerization. A difference in the LCST up to 20°C was found for dark adapted polymer solutions (0% Z ‐isomer) and polymer solutions in the photostationary state (ca. 85% Z ‐isomer). Within this temperature range the polymer can be precipitated by irradiation with light.