Synthesis of dendrimer‐like copolymers based on the star[Polystyrene‐Poly(ethylene oxide)‐Poly(ethoxyethyl glycidyl ether)] terpolymers by click chemistry

The dendrimer‐like copolymers PEEGE‐(PS/PEO)]_n (n ≥ 2) based on the starPolystyrene‐Poly(ethylene oxide)‐Poly(ethoxyethyl glycidyl ether)] star(PS‐PEO‐(PEEGE‐OH))] terpolymers were synthesized by click chemistry. First, the star‐shaped copolymers starPS‐PEO‐(PEEGE‐Alkyne)] (also termed as PEEGE‐(PS/PEO)]₁) were synthesized by the reaction of hydroxyl end group at PEEGE arm (on starPS‐PEO‐(PEEGE‐OH)]) with propargyl bromide. Then, the small molecule 1,4‐diazidobutane (DAB) with two azide groups and pentaerythritol tetrakis (2‐azidoisobutyrate) (PTAB) with four azide groups were synthesized and reacted with PEEGE‐(PS/PEO)]₁ by the click chemistry for dendrimer‐like PEEGE‐(PS/PEO)]₂ and PEEGE‐(PS/PEO)]₄, respectively. However, in the latter case, only the PEEGE‐(PS/PEO)]₃ was formed as the main product because of the steric effect. The final dendrimer‐like PEEGE‐(PS/PEO)]_n copolymers were characterized by SEC and ¹H‐NMR in detail. Comparing with the SEC of their precursor PEEGE‐(PS/PEO)]₁, the curves of PEEGE‐(PS/PEO)]₂ was shifted to the shorter elution time, while that of PEEGE‐(PS/PEO)]_n (n ≥ 3) was shifted to the longer elution time, which was attributed to the different hydrodynamic volume derived from their separate structures and compositions in THF solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4800–4810, 2009