Hybrid Photoiniferter and Ring-Opening Polymerization Yields One-Pot Anisotropic Nanorods

Polymerization-induced self-assembly (PISA) has emerged as a scalable one-pot technique to prepare block copolymer (BCP) nanoparticles. Recently, a PISA process, that results in poly(l-lactide)-b-poly(ethylene glycol) BCP nanoparticles coined ring-opening polymerization (ROP)-induced crystallization-driven self-assembly (ROPI-CDSA), was developed. The resulting nanorods demonstrate a strong propensity for aggregation, resulting in the formation of 2D sheets and 3D networks. This article reports the synthesis of poly(N,N-dimethyl acrylamide)-b-poly(l)-lactide BCP nanoparticles by ROPI-CDSA, utilizing a two-step, one-pot approach. A dual-functionalized photoiniferter is first used for controlled radical polymerization of the acrylamido-based monomer, and the resulting polymer serves as a macroinitiator for organocatalyzed ROP to form the solvophobic polyester block. The resulting nanorods are highly stable and display anisotropy at higher molecular weights (>12k Da) and concentrations (>20% solids) than the previous report. This development expands the chemical scope of ROPI-CDSA BCPs and provides readily accessible nanorods made with biocompatible materials.