“Decoration” of Shell Cross-Linked Reverse Polymer Micelles Using ATRP:  A New Route to Stimuli-Responsive Nanoparticles

Abstract

We demonstrate the use of atom transfer radical polymerization (ATRP) to graft polymers onto preformed shell cross-linked reverse micelles (SCRM). Reverse polymer micelles are first obtained in organic solvents and stabilized by cross-linking of the shell using the photoinduced dimerization of coumarin groups (>310 nm). The structurally locked SCRM are then used as micellar macroinitiators for further polymerization from their surface of monomers such as styrene and dimethylaminoethyl methacrylate (DMAEMA) via ATRP. The decoration of an outer corona of PDMAEMA renders the nanoparticles containing a hydrophilic core soluble in water, with the solubility being sensitive to changes in pH and temperature. In addition, such decorated SCRM are light-responsive. The photoinduced cleavage of cyclobutane bridges (<260 nm) leads to the de-cross-linking of the shell and thus the disintegration of the micellar aggregates. The characterization results, using size-exclusion chromatography (SEC), dynamic light scattering (DLS), and transmission electron microscope (TEM), show an excellent control over the reactions, the molar mass, and the polydispersity of SCRM before and after the surfaceinitiated ATRP. The "decoration" of SCRM offers a new route to designing stimuli-responsive polymer nanostructures that cannot be prepared through only block copolymer self-assembly.

Polymeric micelles: authoritative aspects for drug delivery

“…Decorated shell cross-linked reverse polymer micelles constituted of poly(dimethylaminoethyl methacrylate)-b-poly(methyl methacrylate-random-coumarin methacrylate) and responsive to light were reported by Babin et al [373]. Jiang et al prepared amphiphilic block copolymer micelles whose core-shell structure was disrupted upon irradiation with different wavelengths of light [374,375].…”

Fluorescent Dyes Used in Polymer Carriers as Imaging Agents in Anticancer Therapy

“…The micelles could be disrupted by λ=794 nm NIR light excitation via two-photon absorption [258,259]. Disruption followed from the NIR light-induced removal of coumarin groups from the polypeptide block that shifted the hydrophilic-hydrophobic balance toward the destabilization of the micelles in aqueous solution [260].…”

Macroscopic Photoinduced and Reversible Sol-Gel Conversions of Polymer Materials Containing Photoreactive Coumarin Moieties

“…Subsequent irradiation of the coumarin dimer at λ<300 nm induces cleavage of the cyclobutane ring and the monomer coumarins reform. Various coumarin-functionalized polymer materials, in particular, photo-cross-linking polymers have been reported thus far [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Chujo et al reported photocontrollable swelling behavior of hydrogel films obtained from polyoxazoline having a coumarin moiety [1].…”

“…Zhao et al reported photoinduced size change of nanogels composed of hydrophilic block copolymers containing coumarin moieties. Most of these researches employed film-type gels on a substrate or microscopic gels for the examination of their swelling properties [2][3][4][5][6].…”