Functionalized Stimuli-Responsive Nanocages from Photocleavable Block Copolymers

Abstract

The light-induced formation of pH and temperature-responsive poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) nanocages is demonstrated here. The strategy is based on the self-assembly in aqueous solutions of a photocleavable poly(tert-butyl acrylate)-hv-poly [2-(dimethylamino)ethyl methacrylate] block copolymer (PtBAhv-PDMAEMA, where -hv-is the photocleavable junction) into spherical micelles, followed by first PDMAEMA crosslinking by a bis-iodo compound and then by UV light irradiation. The exposure to light induces the cleavage of the junction between the PtBA core and the cross-linked PDMAEMA shell of the micelles. The PtBA block is then extracted to obtain the desired nanocages. The size change of the nanocages in response to pH and temperature is investigated by dynamic light scattering. Finally, the ability to functionalize the internal cavity of the nanocages is demonstrated. ■ INTRODUCTIONDuring the past decade, the formation of hollow nanocapsules (or nanocages) has attracted extensive attentions. 1−3 Indeed, such type of structure with an empty core domain allows the encapsulation of a large amount or guest molecules which is valuable for drug delivery systems 4,5 and nanoreactors. 6,7 Moreover, hollow nanocapsules open the door to compartmentalization and nature mimics (e.g., cells and viruses). 6,8 With such type of applications in mind, the development of methodologies to produce well-defined, functionalized and responsive, hollow nanocapsules is highly desired.Over the years, hollow polymeric nanocapsules were produced via several methodologies, which can be divided into two categories. The first one involves the direct polymerization of monomers, either in a scaffold 9−11 or onto the surface of a sacrificial nanoparticle. 12,13 The second category relies on the assembly of homopolymers or block copolymers. In this category, the layer-by-layer technique is one of the most attractive technique for the preparation of hollow nanocapsules because the process is environmentally friendly, inexpensive and versatile. 3,14,15 However, the functionality of the internal walls of the nanocage is difficult to control by this technique. The self-assembly of block copolymers has been also used for the production of nanocages since the size of the nanocage membrane and cavity can be easily tuned by the copolymer composition, molecular weight and self-assembly conditions or even by external stimuli. 16 Methodologies involving the self-assembly of copolymers into core−shell structures combined with the migration of the core forming chains into the corona were recently developed. 17,18 Other methodologies involve the self-assembly of copolymer precursors into a core−shell structure combined with the extraction 19−22 or the degradation 4,23−25 of the core forming polymer.Although this last method allows the production of responsive nanocages, the control of the nanocage internal wall functionality is not always trivial. 20 To solve this issue and obtain nanocages with well-defined chemical functionalities, O'Reilly...

Preparation of 2‐(dimethylamino) ethyl methacrylate copolymer micelles for shape memory materials

“…It is well known that poly(2‐(dimethylamino)ethyl methacrylate) (pDMAEMA) is widely used as a biomaterials double hydrophilic copolymer and environmentally sensitive coating due to its unique chemical structure containing–N(CH 3 ) 2 functional groups , which can be further quaternized or betainized . The literature reveals that the functional monomer 2‐(dimethylamino)ethyl methacrylate (DMAEMA) has been widely used to design stimuli‐responsive hydrogels, micelles, brushes, and other functional membranes grafted onto various substrates . In addition to their responsiveness to pH and temperature, DMAEMA‐based copolymers can also respond to external stimuli such as ion strength, selected ions and other factors in solution .…”

Cu(0)-mediated living radical polymerisation in dimethyl lactamide (DML); an unusual green solvent with limited environmental impact

“…In addition to the control over molecular weight and molecular weight distribution, CRPs gave access to the control of the chain-end functionality allowing, for example, for the coupling between polymer-polymer [28][29][30] and polymerprotein 31,32 . Several bromoisobutyrate derivatives were selected to demonstrate that a wide range of functional group can be inserted at the polymer chain-end ( Figure S8): ethyl-2-bromoisobutyrate (EBiB), cholesteryl-2-bromoisobutyrate (Chol-BiB), pyrenyl-2-bromisiobutyrate (Py-BiB), Nsuccinimidyl-2-bromoisobutyrate (Succ-BiB), 2-bromo-2-methyl propionic acid 2-(3,5-dioxo-10-oxa-4-azatricyclo[5.2.1.02,6]dec-8-en-4-yl) ethyl ester (Mal-BiB), adamantyl-2-bromoisobutyrate (Adam-BiB) and dihydroxypropyl-2-bromoisobutyrate (diOH-BiB).…”

Synthesis of amphiphilic poly(ethylene glycol)-block-poly(methyl methacrylate) containing trityl ether acid cleavable junction group and its self-assembly into ordered nanoporous thin films

“…However, most of these methods require harsh conditions, and are limited to certain degradable polymers. To overcome these drawbacks, the introduction of a cleavable linkage between two blocks has been proposed and developed (14)(15)(16)(17)(18), by which the block copolymers can be cleaved rapidly and efficiently under very mild conditions. The cleavage of the junction point of block copolymers in the ordered state followed by removal of the minority block has been proven to be a very useful strategy for the production of nanoporous structures.…”