Toward Unimolecular Micelles with Tunable Dimensions Using Hyperbranched Dendritic-Linear Polymers

Abstract

A library of amphiphilic, hyperbranched dendritic-linear polymers (HBDLPs) are successfully synthesized, and evaluated as potential unimolecular micelles. Hyperbranched macroinitiators (HBMI), extended with poly(ethylene glycol) methacrylate (P(OEGMA)), are afforded via a combination of self-condensing vinyl (co)polymerization (SCV(C)P) and atom transfer radical polymerization (ATRP), providing a versatile two-step synthetic route. The HBDLP architecture and chain lengths are varied, and the effect on the nanoparticle (NP) stability and properties are evaluated. The HBDLPs form predominantly stable and spherical NPs, and the NP dimensions could be tailored by the HBDLP characteristics. The NPs formed are of high molecular weight, and their stability varies with the properties of the corresponding HBDLP. Too small dendritic segment, or too low degree of PEGylation, results to some extent in NP aggregation, while higher molecular weight HBDLPs, with a high amount of hydrophilic segments, appears to form discrete unimolecular micelles. The versatility of the platform is further demonstrated by the convenience of forming a HBDLP with a more complex, linear copolymer extension instead of P(OEGMA).