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Poly(N-acryloxysuccinimide) (PNAS) and poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (P(NAS-co-NVP)) of adjustable molecular weights and narrow polydispersities were prepared by nitroxide-mediated polymerization (NMP) in N,N-dimethylformamide in the presence of free SG1 (N-tert-butyl-N-1-diethylphosphono-)2,2-dimethylpropyl) nitroxide), with MAMA-SG 1 (N-(2-methylpropyl)-N-(1-diethylphosphono-2,2-dimethylpropyl)-O-(2-carboxylprop-2-yl)hydroxylamine) alkoxyamine as initiator. The reactivity ratios of NAS and NVP were determined to be r(NAS) = 0.12 and r(NVP) = 0, indicating a strong alternating tendency for the P(NAS-co-NVP) copolymer. NAS/NVP copolymerization was then performed from a SG1-functionalized poly(D,L-lactice) (PLA-SG1) macro-alkoxyamine as initiator, leading to the corresponding PLA-b-P(NAS-co-NVP) block copolymer, with similar NAS and NVP reactivity ratios as mentioned above. The copolymer was used as a surface modifier for the PLA diafiltration and nanoprecipitation processes to achieve nanoparticles in the range of 450 and 150 nm, respectively. The presence of the functional/hydrophilic P(NAS-co-NVP) block, and particularly the N-succinimidyl (NS) ester moieties at the particle surface, was evidenced by ethanolamine derivatization and zeta potential measurements.

New monoalkyl-substituted lactides were synthesized by reaction of α-hydroxy acids with 2-bromopropionyl bromide, and polymerized with various catalysts in the presence of benzyl alcohol by ring-opening polymerization (ROP). The classic tin(II) 2-ethylhexanoate (Sn(Oct)2) catalyst was leading to polymers with narrow distribution and predictable molecular weights, in polymerizations in bulk or toluene at 100 °C. The polymerization rate was corresponding to the steric hindrance of the alkyl substituents, such as butyl, hexyl, benzyl, isopropyl, and dimethyl groups. A yield of 83% was obtained with the hexyl-substituted lactide after 1 h of polymerization. Excellent conversions (97%) could be achieved by using the alternative catalyst 4-(dimethylamino)pyridine (DMAP). This latter organic catalyst was most efficient in polymerizing the more steric-hindered lactides with good molecular weight and polydispersity control, in comparison to the tin(II) 2-ethylhexanoate and tin(II) trifluoromethane sulfonate [Sn(OTf)2] catalysts. The efficiency of the DMAP catalyst and the variability of the monomer synthesis route for new alkyl-substituted lactides allow to prepare and to envision a wide range of new functionalized polylactides for the elaboration of tailored materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4379–4391, 2004