title: Continuous spin fractionation and characterization by size-exclusion chromatography for styrene-butadiene block copolymers.
abstract: Linear and star-shaped styrene-butadiene block copolymers synthesized by anionic polymerization of butadiene and styrene were fractionated by applying a newly developed large-scale fractionation technique, named continuous spin fractionation (CSF). Their molecular weight and polydispersity index (d=M(w)/M(n)) were measured with size-exclusion chromatography and static light scattering. For the linear triblock copolymer a fractionation via temperature variation turned out to be better suited than the usual isothermal procedure. The star-shaped polymer with the d value of 1.33 was fractionated in two CSF steps to get the targeted sample, which has a considerably more uniform structure and a narrower molecular weight distribution (d=1.11). The corresponding starting linear diblock copolymer was fractionated in one step reducing d from 1.68 to 1.17. With one set of simple laboratory equipment, 1kg polymer can be fractionated per day. Utilizing CSF, for the first time, we fractionated successfully the block copolymers.
authors.affiliation: Department of Chemistry, Wuhan University, 430072 Wuhan, China.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Xiong
authors.forename: John
authors.initials: J
authors.lastname: Eckelt
authors.forename: Bernhard A
authors.initials: BA
authors.lastname: Wolf
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Zhang
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
mesh_terms: D002070:Butadienes / Q000737:chemistry / Q000302:isolation & purification*; D002850:Chromatography, Gel / Q000379:methods*; D008970:Molecular Weight; D011137:Polystyrenes / Q000138:chemical synthesis / Q000302:isolation & purification*; D020058:Styrene / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D002070:Butadienes; D011137:Polystyrenes; D020058:Styrene; C024075:styrofoam