Monodisperse Cylindrical Micelles of Controlled Length with a Liquid‐Crystalline Perfluorinated Core by 1D “Self‐Seeding”

Abstract

Abstract:Precise control over the morphology and dimensions of block copolymer (BCP) micelles has attracted widespread interest due to the potential of this approach to generate functional nanostructures. Incorporation of liquid crystalline (LC) block can provide additional opportunities for varying micellar morphologies, but the formation of uniform micelles with controllable dimensions from LC BCPs has not yet been realized. Here, we report the preparation of monodisperse cylindrical micelles with a LC poly(2-(perfluorooctyl)ethyl methacrylate (PFMA) core via a fragmentationthermal annealing (F-TA) process, resembling the "self-seeding" process of crystalline BCP micelles. The average length of the cylinders increases with annealing temperature from 50 nm (at 35 °C) to 800 nm (at 75 °C) , with a narrow length distribution (Lw / Ln < 1.1). The cylinders exhibit end-to-end coupling behaviour at high concentration and after long-term aging. We also demonstrate the potential application of the cylinders with LC cores as a cargo-carrier by the successful incorporation of a hydrophobic fluorescent dye tagged with a fluorooctyl group.

Semi‐Fluorinated Methacrylates: A Class of Versatile Monomers for Polymerization‐Induced Self‐Assembly

“…The cylindrical morphology was further confirmed by scanning electron microscopy (SEM) characterization in Figure S13 (Supporting Information). Such peculiar self‐assembly behavior is originated from the liquid crystalline (LC) ordering of PFOEMA, which was reported to form smectic phase liquid crystals by our group and others . Different from the self‐assembly of coil–coil block copolymers, which tends to spherical nanoparticles, the smectic LC ordering of PDMA‐ b ‐PFOEMA assemblies entails the layered stacking of the polymer chains, favoring the formation of cylindrical micelles …”

“…Such peculiar self-assembly behavior is originated from the liquid crystalline (LC) ordering of PFOEMA, which was reported to form smectic phase liquid crystals by our group [21] and others. [51,52] Different from the self-assembly of coil-coil block copolymers, which tends to spherical nanoparticles, the smectic LC ordering of PDMA-b-PFOEMA assemblies entails the layered stacking of the polymer chains, favoring the formation of cylindrical micelles. [21] We further surveyed the diameters of the PFOEMA core of the PDMA-b-PFOEMA cylinders and plotted them against the DP of PFOEMA.…”

“…[48][49][50] Besides, their corresponding polymers have tunable lipophobicity depending on the side-chain length of the monomers. As a result, they have significant applications in self-assembly, [51,52] 19 F NMR imaging, [53] coating, [54] etc. [55,56] More importantly, they are soluble in the common organic solvents, such as alcohols, toluene, and dioxane, while the corresponding polymers are not, which meets the criterion of the monomers for PISA.…”

One‐dimensional growth kinetics for formation of cylindrical crystalline micelles of block copolymers

“…Preparation of cylindrical micelles via self‐seeding is reported for other BCPs with PCL, P3HT, polyselenophene, OPV, and so forth as the core‐forming block as well. The self‐seeding method can also be applied to prepare cylindrical micelles with a liquid crystalline core …”

Recent advances in the solution self‐assembly of amphiphilic “rod‐coil” copolymers

“…A number of review articles are available for the self‐assembly of rod‐coil BCPs based on mesogen‐jacketed LC polymers and main‐chain LC polymers . In recent years, side‐chain liquid crystalline polymers (SCLCPs) have been incorporated into rod‐coil BCPs, which show unique self‐assembly behavior in solution . In addition, BCPs containing stimuli‐responsive SCLCPs render their assemblies potential applications in controllable drug release, optoelectronic devices, and so forth.…”