Premium
Synthesis of Photoisomerizable Block Copolymers by Atom Transfer Radical Polymerization
Author(s) -
Huang ChihFeng,
Chen Wei,
Russell Thomas P.,
Balazs Anna C.,
Chang FengChih,
Matyjaszewski Krzysztof
Publication year - 2009
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.200900195
Subject(s) - copolymer , atom transfer radical polymerization , photoisomerization , polymer chemistry , azobenzene , polymerization , polystyrene , moiety , styrene , materials science , chemistry , photochemistry , polymer , stereochemistry , catalysis , organic chemistry , isomerization
A series of polystyrene‐ block ‐poly( n ‐butyl methacrylate) (PS‐ b ‐P n BMA) diblock copolymers (di‐BCPs) with an azobenzene moiety [ trans ‐4‐methacryloyloxyazobenzene (MOAB)] in the P n BMA segment was prepared by atom transfer radical polymerization (ATRP). P( n BMA‐ co ‐MOAB) macroinitiators were prepared by activators regenerated by electron transfer (ARGET) ATRP. The MOAB was slightly more reactive than n BMA, resulting in a weak gradient fashion of copolymer. The macroinitiators were subsequently chain‐extended with styrene. Acceleration of the ATRP rate was observed in the presence of a reducing agent. P( n BMA‐ co ‐MOAB)‐ b ‐PS di‐BCPs were obtained with relatively narrow molecular weight distributions ( $\overline M _{\rm w}$ / $\overline M _{\rm n}$ = 1.16–1.49) and the molecular weights were in good agreement with the theoretical values. The efficiency of photoisomerization of the MOAB units was above 80%. DSC traces showed a single T g suggesting the block copolymers were miscible before UV irradiation. After UV irradiation, the X‐ray reflectivity measurements showed the beating of two frequencies, indicating the formation of island‐hole structure.