Noncovalently Connected Micelles, Nanoparticles, and Metal-Functionalized Nanocages Using Supramolecular Self-Assembly

Abstract

An SCS "pincer"-based nitroxide-mediated polymerization (NMP) initiator has been synthesized and utilized to polymerize tert-butyl acrylate ( ( t )BuA), affording polymers with control over molecular weight and polydispersity. (1)H NMR spectroscopy indicates that the sulfur end group remains intact after deprotection of the P ( t )BuA segment to yield a poly(acrylic acid) segment. The hydrophilic polymer-tethered SCS ligand has been demonstrated to bind to palladium(II), as characterized by a distinctive Pd-C shift in the (13)C NMR spectrum and a diagnostic metal-to-ligand charge-transfer band in the UV-vis spectrum. A pyridine-functionalized NMP initiator has also been synthesized and used to initiate the NMP of styrene with good control and end group fidelity. The binding of these two chain end ligand-functionalized polymers to form an amphiphilic metallosupramolecular diblock copolymer is facile, as indicated through extended (1)H and (13)C NMR studies. The self-assembly of this diblock into well-defined, monodisperse, noncovalently connected micelles (NCCMs) is reported and has been characterized by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The NCCMs were selectively stabilized throughout the shell layer to produce stable noncovalently connected nanoparticles, resulting in a distinctive reduction in the solution hydrodynamic radius and zeta potential compared to those of the precursor micelle. The hydrophobic core domain was then readily removed via dialysis at low pH to afford a hollow polymeric nanocage with well-defined interior functionality. A significant increase in the solution hydrodynamic radius and shape by AFM analysis was observed upon removal of the core, and the hydrophilic nanocages were shown to be ineffective in the sequestration of hydrophobic dye molecules relative to the parent nanoparticle.

Well‐defined poly(oxazoline)‐b‐poly(acrylate) amphiphilic copolymers: From synthesis by polymer–polymer coupling to self‐organization in water

“…Solutions of P(MOx) nb-P(t-BA) m (0.3 mg.mL -1 ) were prepared in DMF which was a good solvent for both P(MOx) and P(t-BA) blocks, dialyzed against MilliQ water, and finally filtered through a membrane with a nominal pore size of 0.45 μm. 1,45 Thus, in water, we expected copolymers to form micelles composed of P(t-BA) micellar core surrounded by a P(MOx) corona. The morphology of polymer aggregates was first studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM).…”

Coordination Chemistry inside Polymeric Nanoreactors: Metal Migration and Cross-Exchange in Amphiphilic Core-Shell Polymer Latexes

“…In addition, the absence of free arm-micelle equilibrium reduces the degree of catalyst leaching. Unimolecular polymeric nanoreactors have been obtained by cross-linking linear polymers, after self-assembly in micellar form, at the level of either the outer shell [3][4][5][6], the inner core [7][8][9][10] or an intermediate corona [11,12]. Nanoreactors with a nanogel core have also been obtained by direct functionalization and cross-linking starting from linear polymers as macroinitiators [13][14][15][16][17][18][19][20].…”

Spacer‐length‐dependent association in polymers with multiple‐hydrogen‐bonded end groups

“…[1][2][3][4] Theoretical work has shown that the domain size and morphology of the phase-separated structures critically depend on the strength of the interpolymer noncovalent interactions. [5][6][7][8][9][10] To achieve these attractive enthalpic interpolymer interactions, end-functionalized homopolymers have been prepared with functional groups capable of noncovalent assembly such as hydrogen bonding, [11][12][13][14][15][16][17][18][19][20] ionic, 21 transition-metal, 22,23 host-guest, [24][25][26] and fluorophilic 27 interactions. Typically, these functional groups are attached to a homopolymer via a short, aliphatic spacer.…”