title: 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 or hydrophilic-hydrophobic balance.
abstract: 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.
authors.affiliation: School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, PR China.
authors.forename: Haixing
authors.initials: H
authors.lastname: Cheng
authors.forename: Shaoai
authors.initials: S
authors.lastname: Xie
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Deyue
authors.initials: D
authors.lastname: Yan
authors.forename: Jintian
authors.initials: J
authors.lastname: Yang
authors.forename: Bing
authors.initials: B
authors.lastname: Ji
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008689:Methacrylates / Q000737:chemistry*; D009757:Nylons / Q000737:chemistry*; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013329:Structure-Activity Relationship; D044366:Transition Temperature
chemical_list: D000178:Acrylamides; D008689:Methacrylates; D009757:Nylons; D011108:Polymers; C407037:poly(2-(dimethylamino)ethyl methacrylate); C428028:poly(N,N-diethylacrylamide); D011092:Polyethylene Glycols