Thermally Responsive Unimolecular Nanoreactors from Amphiphilic Dendrimer-Like Copolymer Prepared via Anionic Polymerization and Cross Metathesis Reaction

Abstract

Amphiphilic dendrimer-like polymers are expected to be promising candidates as micro containers or carriers due to their much larger size in relative to regular dendrimers. In the present study, we synthesize amphiphilic dendrimer-like copolymers possessing interior poly­(styrene) segments and peripheral poly­(ethylene oxide) (PEO) segments through iterative anionic polymerization, hydrosilylation, coupling, followed by olefin cross-metathesis with a PEO macromonomer bearing acrylic terminus (denoted as PEGMEA480). The molecular weight of the resulting dendrimer-like copolymer, G3-g-PEO2900, is as large as 2.16 × 106, with number of outer PEO arms up to 2900, and the average diameter 32.8 nm in solution. The behavior of the dendritic product as unimolecular micelles is investigated, using dynamic light scattering (DLS) and pyrene probing, together with the thermal responsiveness arising from the low critical solution temperature (LCST) of PEO segments. The amphiphilic dendrimer-like copolymers are used as nanoreactors for the nucleophilic displacement of benzyl halide by KSCN and the hydrolysis reaction of benzyl halide, in which significant increases in the reaction yields are observed. More interestingly, the nanoreactor can be regulated activation-and-deactivation due to thermoresponsiveness of peripheral PEO segments, and the dendritic nanoreactor is recyclable for at least 7 times.

pH-Switchable LCST/UCST-type thermosensitive behaviors of phenylalanine-modified zwitterionic dendrimers

“…16 LCST-type thermosensitive PAMAM dendrimers and dendritic polymers have been produced by modication with various compounds, oligo(ethylene glycol), N-isopropyl groups and elastin-like peptides, which are useful for drug delivery and substance separation. [17][18][19][20][21][22][23][24][25] PAMAM dendrimers modied with phenylalanine (Phe) are also thermosensitive, but their thermosensitivity depends on their terminal groups. The amino-terminal Phe-modied PAMAM dendrimer (PAMAM-Phe) exhibited LCSTtype thermosensitivity above pH 6.…”

The Role of Branch Cell Symmetry and Other Critical Nanoscale Design Parameters in the Determination of Dendrimer Encapsulation Properties

“…(b) Thermally responsive unimolecular reactors exhibiting low critical solution temperature (LCST) properties due to PEO periphery. Reprinted with permission from [196]. Copyright 2019 American Chemical Society.…”

A Sensitive and Simple Enzyme-Linked Immunosorbent Assay Using Polymer as Carrier

“…The specific synthetic route for G3-g-PEO 2900 is described in detail in the literature 22) and will not be repeated here. The general synthesis process is as follows.…”

“…[19][20][21] In this study, we report a new ELISA method using a polymer as a carrier (Polymer-ELISA) instead of traditional 96-microzone plates and current 96-microzone paper plates. 22,23) Polymers have many advantages over other reaction carriers, such as their abundant functional groups, numerous branched chains and large internal voids. 24,25) In addition, the polymer used in this study has no effect on the activity of biological molecules.…”

“…The polymer used in this study is G3-g-PEO 2900 . 22) The molecular weight of the dendrimerlike copolymer peripheral polyethylene oxide (PEO) is as large as 2.16×10 6 , with up to 2900…”