2.3. Synthesis of Poly(N,N-(dimethylamino)ethyl methacrylate) Chain Transfer Agent (PDMAEMA-CTA)

The PDMAEMA-CTA with a targeted polymerization degree of 160 were prepared as follows: DMAEMA (11.32 g, 0.072 mol), 2-cyano-2-propyl benzodithioate (CPDB) (0.10 g, 0.45 mmol) and azobisisobutyronitrile (AIBN) (0.01g, 0.06 mmol), were dissolved in 2 mL of toluene. The mixture was purged with nitrogen for 30 min and then heated at 60 °C for 24 h. The reaction was quenched by rapid cooling with ice-water. After the removal of toluene using a rotary evaporator, the mixture was dissolved in THF and precipitated in n-hexane. The polymer was filtered and dried under vacuum at room temperature overnight yield final product of 9.17 g (81 %). The molecular weight (M_n = 25,000 g·mol⁻¹) and molecular weight distribution (PDI = 1.20) of the product were determined by SEC with PS standards. ¹H NMR (400 MHz, CDCl₃, δ): 0.86-1.10 (d, 370 H, CCH₃ from PDMAEMA), 1.81 (270 H, CCH₃CH₂ from PDMAEMA), 2.22 (s, 820 H, N(CH₃)₂ from PDMAEMA), 2.50(t, 266 H, NCH₂CH₂O from PDMAEMA), 3.99(t, 266 H, NCH₂CH₂O from PDMAEMA), 7.79(m, 2H, o-ArH, from chain transfer agent), 7.46(m, 1H, p-ArH, from chain transfer agent). Polymerization degree of PDMAEMA was determined to be 133. Number-average molecular weight of PDMAEMA-CTA was determined to be 157 g·mol⁻¹ × 133 + 221 g·mol⁻¹ = 21,102 g·mol⁻¹.