Polymerization of a new thermo-responsive copolymer with N-vinylcaprolactam and its application in recyclable aqueous two-phase systems with another thermo-responsive polymer

Junfen Wan,Zhenping Wang,Xuejun Cao,Daisong Hou,Wenying Dong

doi:10.1186/s40643-018-0231-7

Abstract

BackgroundThe recovery characteristics of phase-forming polymers are essential for aqueous two-phase systems (ATPS) to recycle in bioseparation engineering.ResultsA new thermo-responsive copolymer (PVBAm) is suggested based on N-vinylcaprolactam, acrylamide, and butyl methacrylate. Together with another thermo-responsive polymer, poly (N-isopropyl acrylamide) (PN), it has been applied to form a recyclable ATPS. PVBAm and PN were designed to obtain structures and molecular weights allowing a lower critical solution temperature (LCST). By polymerization optimization, both PN and PVBAm were obtained with recoveries 98.5% and 95% above their LCST (i.e., PN 32.5 °C and PVBAm 40.5 °C), respectively, which allows each ATPS phase to be effectively recycled. The recycled ATPS based on PVBAm and PN was applied to the partitioning of vitamin B12. Under optimized conditions (5% PVBAm/3.5 %PN ATPS, in the presence of 0.8 M KCl, pH 4.0), the partition coefficient of vitamin B12 reached a value of 5.81.ConclusionThe new ATPS based on the thermo-responsive copolymer PVBAm/PN possessed appropriate recycling characteristics regarding LCST, as well as recovery and phase separation characteristics.

Highlights

The recovery characteristics of phase-forming polymers are essential for aqueous two-phase systems (ATPS) to recycle in bioseparation engineering
We have recently developed new ATPS forming polymers based on N-isopropyl acrylamide (NIPA) or N-vinylcaprolactam (NVCL) as monomers
Viscosity average molecular weight During polymerization, the viscosity average molecular weight (Mv) of the polymer is strongly influenced by the reaction temperature and the amount of the initiator AIBN

Summary

Introduction

The recovery characteristics of phase-forming polymers are essential for aqueous two-phase systems (ATPS) to recycle in bioseparation engineering. Aqueous two-phase systems (ATPS) are promising alternatives to extract and purify biomolecules thanks to high biocompatibility and readiness to scaling up (Molino et al 2013). Conventional ATPS were traditionally prepared from polyethylene glycol and salts or dextran and applied for the extraction of different biomolecules (Ramesh and Murty 2015). Polymers based on ethylene oxide-propylene oxide (EOPO) have been extensively studied in TR ATPS (Koon et al 2015). In 1995, Berggren et al (1995) reported the first preparation of ATPS based on an ethylene oxide–propylene oxide (EOPO) TR copolymer. Persson et al (1999) used E O50PO50 to form ATPS with a hydrophobically modified random copolymer of EO and PO (HM-EOPO).

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Conclusion