Abstract: In order to address the incomplete polymerization of different monomers resulted by their different reactivities, we perform a polymerization of β-lactam monomer bearing hydrophobic sidechains, 3, 3, 4, 4-tetramethylazetidine-2-one (TM) and another monomer having positively charged groups in the sidechain, 3-(tert-butyloxycarbonyl aminomethyl)-4, 4-dimethylazetidin-2-one (MM), which show slow reactivity during polymerization. The polymerization condition of these monomers was optimized by exploring different monomer concentrations, reaction solvents and initiators. The results indicated that initiators with potassium counter ion can initiate a faster polymerization of β-lactam monomers and result in a higher conversion of monomers compared with that with lithium counter ion. In addition, increasing the reactant concentration and optimizing the reaction solvent could also increase the reaction rate. The investigations on the minimum inhibitory concentration (ρ_MIC) of synthesized polymers revealed that the polymers obtained at the optimized reaction conditions presented slightly increased antimicrobial activities against some types of microbes.