Synthesis and fluorescence properties of hyperbranched poly(amidoamine)s with high density tertiary nitrogen

Hyperbranched poly(amidoamine)s with high density tertiary nitrogen (HPAMAMs-OH) were prepared via the two-step reactions. Firstly, hyperbranched poly(amidoamine)s (HPAMAMs) were synthesized by Michael addition of 1-(2-aminoethyl) piperazine (AEPZ) and methyl acrylate (MA) and then alkylation of the residual amino protons of hyperbranched poly(amidoamine)s (HPAMAMs) with propylene oxide (PO) in ethanol was performed. The fluorescence properties of HPAMAMs and HPAMAMs-OH were investigated. It was found that the fluorescence intensity of the polymers increased correspondingly with the increasing of the tertiary nitrogen in the molecular structure. The tertiary nitrogen with lone pair electrons inside the molecular structure played an important role in the photoluminescence. The complex with nano gold encapsulated in the interior of the HPAMAMs-OH presented greatly enhanced emission. Those results show that the nano gold may be used to adjust the fluorescence properties of HPAMAMs-OH and may extend potential applications of HPAMAMs-OH and gold nanoparticles. Hyperbranched poly(amidoamine)s with high density tertiary nitrogen (HPAMAMs-OH), obtained by alkylation of the residual amino protons of hyperbranched poly(amidoamine)s (HPAMAMs) in ethanol with propylene oxide (PO), can emit bright blue fluorescence under excitation wavelengths.