Copolymer of tetraethylenepentamine and ethylene glycol diacrylate: Synthesis and degradation

A degradable polycation with high density of discrete charge was synthesized from tetraethylenepentamine (TEPA) and ethylene glycol diacrylate (EGDA) based on Michael addition and amidation. The cationic polymer synthesized here was denoted as PTE. Polymerization was monitored by H-1 NMR spectroscopy. According to H-1 NMR spectra, Michael addition proceeded more rapidly than amidation. After 6 h, there were no double bonds left, while amidation existed throughout the polymerization. In addition, when PTE was synthesized in chloroform and dichloromethane, respectively, there were some structural differences as shown by H-1 NMR spectroscopy. The degradation laws of PTE in aqueous solution were studied by H-1 NMR and viscosity measurements. When PTE was dissolved in deionized water, degradation proceeded in high velocity. However, in NaH2PO4 aqueous solution, degradation was slowered. Degradation at 37 degrees C proceeded obviously more rapidly than that at 25 degrees C. A certain degree of amidation facilitated the reduction of degradation velocity. The effect of concentration on degradation was not obvious. Interestingly, PTE synthesized in CHCl3 was degraded more rapidly than that in CH2Cl2. (C) 2008 Elsevier Ltd. All rights reserved.