title: Characterization of ultrahigh-molecular weight cationic polyacrylamide using frit-inlet asymmetrical flow field-flow fractionation and multi-angle light scattering.
abstract: In this study, frit inlet asymmetrical flow field-flow fractionation (FlFFF) with multi-angle light scattering (MALS) and differential refractive index (DRI) detection is utilized for size separation, determination of molecular weight (MW), and conformation of ultrahigh-MW (10(7)-10(9) g/mol) cationic polyacrylamides (C-PAMs), a class of water-soluble copolymers based on acrylamide and vinyl-type comonomers with quaternary ammonium cations that are widely used in wastewater treatment and in paper industries. Linear and branched C-PAM copolymers prepared in two different polymerization methods (solution and emulsion) from varying amounts of crosslinking agent and initiator were size fractionated by FlFFF with field-programming. It was found experimentally that the linear copolymers from both polymerization methods were less than 10(8) g/mol in MW with compact, nearly spherical structures, while the branched C-PAM copolymers from the emulsion polymerization showed a significant increase in average MW up to ∼ 10(9)g/mol, which was about 20-fold greater than those from the solution method, and the branched copolymers had more compact or shrunken conformations. While both linear and branched copolymers less than 10(8) g/mol MW were well resolved in an increasing order of MW (normal mode), it was noted that branched copolymers prepared through emulsion polymerization exhibited significantly larger MWs of 10(8-)10(9) g/mol and eluted in the steric/hyperlayer mode, in which the elution order is reversed in an extreme run condition (strong initial field strength followed by a fast field decay during programming).
authors.affiliation: Department of Chemistry, Yonsei University, Seoul 120-749, South Korea.
authors.forename: Sohee
authors.initials: S
authors.lastname: Woo
authors.affiliation: Department of Chemistry, Yonsei University, Seoul 120-749, South Korea.
authors.forename: Ju Yong
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Kolon Life Science Inc., 13 Kolon-ro, Gwacheon-si, Gyeonggi-do 427-709, South Korea.
authors.forename: Woonjin
authors.initials: W
authors.lastname: Choi
authors.affiliation: Department of Chemistry, Yonsei University, Seoul 120-749, South Korea. Electronic address: mhmoon@yonsei.ac.kr.
authors.forename: Myeong Hee
authors.initials: MH
authors.lastname: Moon
mesh_terms: D000180:Acrylic Resins / Q000032:analysis*; D002412:Cations; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D031521:Fractionation, Field Flow; D008027:Light; D008968:Molecular Conformation; D008970:Molecular Weight; D012031:Refractometry; D012542:Scattering, Radiation; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D002412:Cations; D000099166:Polyacrylamides
keywords: Branched; C-PAM; Cationic polyacrylamide; Field-flow fractionation; Molecular weight determination; Multi-angle light scattering