Water-Soluble, Unimolecular Containers Based on Amphiphilic Multiarm Star Block Copolymers

Abstract

A new class of water-soluble, amphiphilic star block copolymers with a large number of arms was prepared by sequential atom transfer radical polymerization (ATRP) of n-butyl methacrylate (BMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA). As the macroinitiator for the ATRP, a 2-bromoisobutyric acid functionalized fourth-generation hyperbranched polyester (Boltorn H40) was used, which allowed the preparation of star polymers that contained on average 20 diblock copolymer arms. The synthetic concept was validated by AFM experiments, which allowed direct visualization of single molecules of the multiarm star block copolymers. DSC and SAXS experiments on bulk samples suggested a microphase-separated structure, in agreement with the core−shell architecture of the polymers. SAXS experiments on aqueous solutions indicated that the star block copolymers can be regarded as unimolecular micelles composed of a PBMA core and a diffuse PPEGMA corona. The ability of the polymers to encapsulate and release hydrophobic guests was evaluated using 1H NMR spectroscopy. In dilute aqueous solution, these polymers act as unimolecular containers that can be loaded with up to 27 wt % hydrophobic guest molecules.

Design and Use of Organic Nanoparticles Prepared from Star-Shaped Polymers with Reactive End Groups

“…ATRP was chosen as the polymerization technique for two reasons. First, by choosing the right reaction conditions, star-shaped polymers can be prepared in a controlled way with a minimal extent of star-star coupling [6][7][8][9][10][11][12][13][14][15] . Secondly, after ATRP of acrylates, a secondary bromine end group is available at the end of each arm of the stars for further conversion into reactive groups.…”

“…Recent developments in atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer polymerization (RAFT) made it possible to use radical polymerization for the controlled synthesis of star polymers [3][4][5] . For these techniques, a variety of multifunctional initiators has been developed and successfully used [6][7][8][9][10][11][12][13][14][15] .…”

“…star(PS-b-PEO) 6 ). Recently, we described the synthesis of star-shaped poly(tetrahydrofuran) with allyl and hydroxyl end groups 23 .…”

A unimolecular nanocapsule: Encapsulation property of amphiphilic polymer based on hyperbranched polythreitol

“…Therefore, there have been many studies on the design and synthesis of amphiphilic dendritic polymers as nanomaterials, such as a drug delivery agent, [5][6][7][8][9][10] nanoreactors, [11][12][13][14] and nanocapsules. [15][16][17][18][19][20][21][22][23] For example, Fréchet et al…”

Hyperbranched poly(ether sulfone)s: preparation and application to ion-exchange membranes

“…63,64 Hyperbranched polymers are frequently used as the core of core-shell block copolymers, where the shell block is grown from the functional groups of the hyperbranched polymer. [65][66][67] Hyperbranched polymers have also been grown from linear polymers to form diblock, 68 gridlock 69,70 and graft copolymers. 41,71,72 Hyperbranched polymers have also been prepared from one or more oligomeric monomers to yield products that have additional flexibility.…”