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

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 (P VBAm) is suggested based on N-vinylcaprolactam, acrylamide, and butyl methacrylate. Together with another thermo-responsive polymer, poly (N-isopropyl acrylamide) (P N), it has been applied to form a recyclable ATPS. P VBAm and P N were designed to obtain structures and molecular weights allowing a lower critical solution temperature (LCST). By polymerization optimization, both P N and P VBAm were obtained with recoveries 98.5% and 95% above their LCST (i.e., P N 32.5 °C and P VBAm 40.5 °C), respectively, which allows each ATPS phase to be effectively recycled. The recycled ATPS based on P VBAm and P N 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 P VBAm/P N possessed appropriate recycling characteristics regarding LCST, as well as recovery and phase separation characteristics.

Keywords

• Aqueous two-phase systems
• Thermo-responsive polymer
• N-isopropyl acrylamide
• N-vinylcaprolactam