Elaboration of densely functionalized polylactide nanoparticles from <i>N</i>‐acryloxysuccinimide‐based block copolymers

Abstract

Abstract 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‐SG1 ( 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 ‐lactide) (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. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011