Effect of Degree of Branching on the Thermoresponsive Phase Transition Behaviors of Hyperbranched Multiarm Copolymers: Comparison of Systems with LCST Transition Based on Coil-to-Globule Transition of Hydrophilic-Hydrophobic Balance
writer：Cheng, H. X.; Xie, S. A.; Zhou, Y. F.*; Huang, W.; Yan, D. Y.; Yang, J.T.; Ji, B.
keywords：Phase Transition, Coil-to-Globule Transition, Hyperbranched
source：期刊
specific source：J. Phys. Chem. B 2010, 114, 6291. http://pubs.acs.org/doi/pdf/10.1021/jp100714j
Issue time：2010年
This work reports for the first
time the influence of degree of branching (DB) on the thermoresponsive phase
transition behaviors of hyperbranched multiarm copolymers. Two series of
PEHO-star-PEOs (series A) and PEHO-star-PDMAEMAs (series B) with the hydrophobic
DB-variable PEHO core and different kinds of linear arms (PEO arms or PDMAEMA
arms) were synthesized. It was found these two series demonstrate
thermoresponsive phase transitions with the lower critical solution temperature
(LCST). The studies on the LCST transition mechanism indicate that series A
belongs to the thermoresponsive polymer system with LCST transition based on
hydrophilic?hydrophobic balance, while series B belongs to the thermoresponsive
polymer system with LCST transition based on coil-to-globule transition.
Correspondingly, there is a big difference in the DB dependence of LCST
transition between series A and series B. For series A, the LCST phase
transition is highly dependent on the DB of the PEHO core in copolymers. For
series B, the LCST phase transition is independent of the DB but dependent on
solution pH. Such results may extend the knowledge on the structure?activity
relationship of thermoresponsive highly branched polymers.