A method of synthesizing a random copolymer of polyethyleneimine and polyethylene glycol, comprising exposing ethanolamine in a solution to electromagnetic radiation for a sufficient time to polymerize the ethanolamine (OHCH2CH2NH2) and thereby resulting in formation of the randome copolymer comprising polyethyleneimine and poly(ethylene glycol), wherein the polyethyleneimine comprises ethyleneimine (—CH2CH2NH—) unit and the polyethylene glycol comprises ethylene glycol (—CH2CH2O—) unit, and the polyethylenimine of the random copolymer has a substantially linear backbone.
