Synthesis and Characterization of Methoxy Poly(ethylene glycol)-co-poly(β-amino ester) formed by Linear and Cyclic Hexylamines as Polymeric Micelles

Methoxy poly(ethylene glycol)-co-poly(beta-amino ester) (MPEG-PbAE) was synthesized using pre-modified acrylated-end methoxy poly(ethylene glycol) (MPEG-ac), 1,6-hexanediol diacrylate, linear hexylamine (A) and cyclic hexylamine (B) as reactants. The MPEG-PbAE copolymer A and B were expected to form micelles where MPEG acts as the hydrophilic shell and the PbAE with hexyl groups acts as the hydrophobic core. The modified MPEG-ac, synthesized MPEG-PbAE copolymer A and B were then characterized. The Fourier transformed infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR) confirmed the modification of hydroxyl end group of MPEG to acrylate end group. It was found that the copolymer A is more suitable as drug carrier by the comparison between copolymer A formed by linear hexylamine and copolymer B formed by cyclic hexylamine. Gel permeation chromatography (GPC) showed that the number average molecular weight, Mn of the copolymer A was 11216 with polydispersity index (PDI) 1.1925. The critical micelle concentration (CMC) of copolymer A in aqueous solution at pH7.4 is 84.6 mg/L. The average micellar size that are obtained from dynamic light scattering (DLS) analysis was 26.25+/-0.149 nm.