2.2. Synthesis of PBMP

The dimethyl methacryloyloxyethyl phosphate (DMOEP) monomer and the PBMP polymer were synthesized according to a previously reported procedure [16,21]. First, the mixture of DCP (120 mmol) and pyridine (120 mmol) was slowly added to 250 mL of chloroform containing 100 mmol of HEMA on ice. The mixture was stirred for 2 h and washed with 0.01 M HCl, NaHCO₃ and brine. The organic layer was collected and evaporated to obtain the DMOEP monomer as pale-yellow oil.

Then, DMOEP (14 mmol) and BMA (14 mmol) were dissolved in the mixture of EtOH and THF (28 mL, v/v = 4:1). For the initiation of radical polymerization, AIBN (0.28 mmol) was added to the solution and the mixture was incubated with overnight stirring at 60 °C. After evaporization of the solvent, poly(BMA-co-DMOEP) was obtained as a transparent oil form. The polymer was demethylated by using TMSBr. The polymer in anhydrous chloroform (40 mL) was slowly added with TMSBr (56 mmol). The mixed solution was first stirred in an ice bath for 1 h and at ambient temperature for another 2 h. Following the evaporation of the solvent, 100 mL of H₂O/THF with a volume ratio of 1:7 was added. After overnight reaction at ambient temperature, the solvent was evaporated. The resulting product was dialyzed against MeOH and deionized water using a dialysis membrane (MWCO = 3000 g/mol; Spectrum Labs, USA). After freeze drying, PBMP was obtained as a white powder with the purified yield of 68.5%.