title: A novel polymeric monolith prepared with multi-acrylate crosslinker for retention-independent efficient separation of small molecules in capillary liquid chromatography.
abstract: Low column efficiency for small molecules in reversed-phase chromatography is a major problem commonly encountered in polymer-based monoliths. Herein, a novel highly crosslinked porous polymeric monolith was in situ prepared by using a multi-acrylate monomer, dipentaerythritol penta-/hexa-acrylate (DPEPA), as crosslinker, which copolymerized with lauryl methacrylate (LMA) as functional monomer in a UV-transparent fused-silica capillary via photo-initiated free-radical polymerization within 5 min. The mechanical stability and permeability of the resulting poly(LMA-co-DPEPA) monolith were characterized in detail. One series of highly crosslinked poly(LMA-co-DPEPA) columns were prepared with relatively higher content of crosslinker (63.3%) in the precursor. Although they exhibited lower permeability, high column efficiency for alkylbenzenes was acquired in cLC, and the minimum plate height (column B) was in the range of 6.04-9.00 μm, corresponding to 111,000-165,000 N m(-1). Meanwhile, another series of poly(LMA-co-DPEPA) columns prepared with relatively lower content of crosslinker (52.7%) in the precursor exhibited higher permeability, but the minimum plate height (column E) was relatively low in the range of 10.75-20.04 μm for alkylbenzenes, corresponding to 50,000-93,000 N m(-1). Compared with common poly(LMA-co-EDMA) columns previously reported, the highly crosslinked poly(LMA-co-DPEPA) columns using a multi-acrylate monomer as crosslinker possessed remarkably high column efficiency for small molecules in cLC. By plotting of plate height (H) of alkylbenzenes versus the linear velocity (u) of mobile phase, the results revealed a retention-independent efficient performance of small molecules in the isocratic elution, indicating that the use of multi-functional crosslinker possibly prevents the generation of gel-like micropores in the poly(LMA-co-DPEPA) monolith, reducing the mass transfer resistance (C-term).
authors.affiliation: Key Laboratory of Synthetic and Natural Function Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710069, China; Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China. Electronic address: junjieou@dicp.ac.cn.
authors.forename: Junjie
authors.initials: J
authors.lastname: Ou
authors.affiliation: Key Laboratory of Synthetic and Natural Function Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710069, China. Electronic address: ymwei@nwu.edu.cn.
authors.forename: Yinmao
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhongshan
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Lianfang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China. Electronic address: hanfazou@dicp.ac.cn.
authors.forename: Hanfa
authors.initials: H
authors.lastname: Zou
keywords: Capillary liquid chromatography; Dipentaerythritol penta-/hexa-acrylate; Photo-initiated polymerization; Polymer monoliths