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

Abstract

Background: The recovery characteristics of phase-forming polymers are essential for aqueous two-phase systems (ATPS) to recycle in bioseparation engineering. Results: A 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. Conclusion: The new ATPS based on the thermo-responsive copolymer PVBAm/PN possessed appropriate recycling characteristics regarding LCST, as well as recovery and phase separation characteristics.