posted on 2021-11-09, 20:06authored byLinda Salminen, Erno Karjalainen, Vladimir Aseyev, Heikki Tenhu
Poly(diisopropylaminoethyl
methacrylate) (PDPA) is a pH- and thermally
responsive water-soluble polymer. This study deepens the understanding
of its phase separation behavior upon heating. Phase separation upon
heating was investigated in salt solutions of varying pH and ionic
strength. The effect of the counterion on the phase transition upon
heating is clearly demonstrated for chloride-, phosphate-, and citrate-anions.
Phase separation did not occur in pure water. The buffer solutions
exhibited similar cloud points, but phase separation occurred in different
pH ranges and with different mechanisms. The solution behavior of
a block copolymer comprising poly(dimethylaminoethyl methacrylate)
(PDMAEMA) and PDPA was investigated. Since the PDMAEMA and PDPA blocks
phase separate within different pH- and temperature ranges, the block
copolymer forms micelle-like structures at high temperature or pH.