title: LCST and UCST in One: Double Thermoresponsive Behavior of Block Copolymers of Poly(ethylene glycol) and Poly(acrylamide-co-acrylonitrile).
abstract: The change in thermoresponsive behavior from a single phase transition of upper critical solution temperature (UCST)-type of an acrylamide-acrylonitrile copolymer (AAm-co-AN) to a double responsive behavior (LCST-UCST-type (LCST, lower critical solution temperature)) in water by the introduction of a poly(ethylene glycol) (PEG) block is highlighted in the present work. The polymer is synthesized in a simple way by free-radical polymerization of acrylamide and acrylonitrile using a poly(ethylene glycol) (PEG) macro-azoinitiator. The dual thermoresponsive behavior was observed in a wide range of concentrations repeatable for many cycles with very small hysteresis depending upon the ratio of AAm, AN and PEG. Static light scattering (SLS) and dynamic light scattering (DLS) together with turbidity photometry and transmission electron microscopy confirmed a unique phase transition behavior due to the temperature dependent change in the morphology from micelles to agglomerates. The low cytotoxicity and two-in-one thermoresponsive behavior makes the polymer promising for biomedical applications in the future.
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Käfer
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Fangyao
authors.initials: F
authors.lastname: Liu
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Ullrich
authors.initials: U
authors.lastname: Stahlschmidt
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Valérie
authors.initials: V
authors.lastname: Jérôme
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Ruth
authors.initials: R
authors.lastname: Freitag
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Karg
authors.affiliation: †Macromolecular Chemistry II and Center for Colloids and Interfaces, ‡Physical Chemistry I, and §Chair for Process Biotechnology, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Seema
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D000180:Acrylic Resins / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D010316:Particle Size; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D013696:Temperature; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D011092:Polyethylene Glycols; D012996:Solutions; D000099166:Polyacrylamides; C010504:polyacrylonitrile