Synthesis and reactions of cysteine-based telechelic polymers

Abstract

The radical polyaddition of N-4-vinylbenzoyl-L-cysteine methyl ester (VCM) was carried out in the presence of 2,2′-azobisisobutyronitrile (AIBN, 3 mol %) as an initiator in dimethyl formamide (DMF) with monomer concentrations of 0.5 and 1.0 M at 60 °C for 20 h under nitrogen atmosphere to afford the corresponding polymers [poly(VCM), PVCM] with number-average molecular weights (Mn)'s of 5300 and 18,000 in 92 and 95% yields, respectively. The obtained polymers had a heterotelechelic structure with thiol and olefin end moieties. The radical polymerization of methyl methacrylate and trityl methacrylate was carried out in the presence of PVCM with AIBN (3 mol %) as an initiator in DMF at 60 °C for 20 h to afford the block copolymers with Mn values in the range of 13,000–26,800 in good yields. PVCM [Mn = 18,000; polydispersity (Mw/Mn) = 1.56] was treated with 4 equiv of NaOH aq. (1.0 M) to afford the polymer having carboxyl groups in the side chain with a Mn of 17,300 and Mw/Mn of 1.88 in 95% yield and was also oxidized to polysulfoxide and polysulfone with 4 equiv of H2O2 per sulfide unit in CH2Cl2 (1.0 M) for 20 h. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 23–31, 2001