https://doi.org/10.1039/D1MA01072G
“Preparation of cross-linked PEI sorbents
Sorbents were named according to the ratios of amine : alkyl bromide groups in the starting materials. Sorbents were either prepared in a 40 mL vial, indicated by (V), or a 250 mL round-bottom flask (R).
1 : 1 (V), 3 : 1 (V), 5 : 1 (V), 10 : 1 (V), 25 : 1 (V) were prepared in a 40 mL vial by adding a solution of PEI (31 mg, 0.72 mmol; 91 mg, 2.11 mmol; 140 mg, 3.25 mmol; 301 mg, 6.99 mmol; 731 mg, 16.97 mmol, respectively) dissolved in 6 mL THF at 82 °C, to a solution of 4BMFPT (150 mg, 0.234 mmol) dissolved in 29 mL THF at 82 °C. The PEI was washed from the vial with an additional volume of THF (3 mL; 3 mL; 3 mL; 6 mL; 6 mL, respectively) on combination of the reagents. The reaction mixtures were stirred at 82 °C for three nights, then the obtained solid products were separated from the solvent by centrifugation. Approx. 200 mL acetone was added to the products and the mixtures were stirred for 3 days then centrifuged to remove acetone. The products were stirred overnight in a solution of approximately 66 mg of KOH (1.18 mmol) dissolved in 106 mL of a 50 : 50 mixture of ethanol and water to remove the HBr formed during the reaction. The products were then washed in 106 mL of a 50 : 50 mixture of ethanol and water for 2.5 hours then this step was repeated. The products were stirred in approx. 112 mL ethanol for three nights, then centrifuged and dried in an oven overnight at 80 °C. The products were gently ground in a mortar prior to analysis. Yields: 1 : 1 (V), 8.0 mg; 3 : 1 (V), 109.9 mg; 5 : 1 (V), 123.1 mg; 10 : 1 (V), 326.7 mg; 25 : 1 (V), 544.8 mg.
10 : 1 (R) was prepared in a 250 mL round-bottom flask by adding a solution of PEI (317 mg, 7.36 mmol) dissolved in 5 mL THF at 60 °C to a solution of 4BMFPT (162 mg, 0.252 mmol) dissolved in 16 mL THF at 60 °C. The solution was stirred at 66 °C overnight, then the obtained solid product was separated from the solvent by centrifugation. Approx. 50 mL acetone was added to the product and the mixture stirred for approx. 1 hour, then centrifuged to remove the acetone. The product was stirred overnight in a solution of approximately 65 mg of KOH (1.18 mmol) dissolved in 100 mL of a 50 : 50 mixture of ethanol and water to remove the HBr formed during the reaction. The product was then washed in 100 mL of a 50 : 50 mixture of ethanol and water for 3 hours then this step was repeated. The product was stirred in approx. 75 mL ethanol overnight, centrifuged, and then dried in an oven for 3 nights at 70 °C. The product was gently ground in a mortar prior to analysis. 334.5 mg of product was obtained.”