Nanostructured Heteroarm Star Block Terpolymers via an Extension of the “In-Out” Polymerization Route

Brush-First and ROMP-Out with Functional (Macro)monomers: Method Development, Structural Investigations, and Applications of an Expanded Brush-Arm Star Polymer Platform

The efficient synthesis of complex functional polymeric nanomaterials is often challenging. Ru-initiated ring-opening metathesis polymerization (ROMP) of multivalent macromonomers followed by cross-linking to form brush-arm star (BASP) polymers enables access to well-defined nano-structures with diverse functionality. This "brush-first" method leaves active Ru in the BASP microgel core, which could potentially be used in a subsequent "ROMP-out" (RO) step to introduce further modifications to the BASP structure via the addition of (macro)monomers. Here, we study this RO approach in depth. The efficiency of RO is assessed for a variety of BASP compositions using a combination of inductively coupled plasma mass spectrometry and gel permeation chromatography. To demonstrate the modularity of the RO process, arylboronic acid-functionalized BASPs were prepared; uptake of these RO-BASPs into hypersialylated cancer cells was enhanced relative to non-functionalized BASPs as determined by flow cytometry and fluorescence microscopy. In addition, the self-assembly of miktoarm BASPs prepared via brush-first and RO with different macromonomers is demonstrated. The combination of brush-first ROMP with RO provides a simple, modular strategy for access to a wide array of functional nanomaterials.

Star polymer-based unimolecular micelles and their application in bio-imaging and diagnosis

As a novel kind of polymer with covalently linked core-shell structure, star polymers behave in nanostructure in aqueous medium at all concentration range, as unimolecular micelles at high dilution condition and multi-micelle aggregates in other situations. The unique morphologies endow star polymers with excellent stability and functions, making them a promising platform for bio-application. A variety of functions including imaging and therapeutics can be achieved through rational structure design of star polymers, and the existence of plentiful end-groups on shell offers the opportunity for further modification. In the last decades, star polymers have become an attracting platform on fabrication of novel nano-systems for bio-imaging and diagnosis. Focusing on the specific topology and physicochemical properties of star polymers, we have reviewed recent development of star polymer-based unimolecular micelles and their bio-application in imaging and diagnosis. The main content of this review summarizes the synthesis of integrated architecture of star polymers and their self-assembly behavior in aqueous medium, focusing especially on the recent advances on their bio-imaging application and diagnosis use. Finally, we conclude with remarks and give some outlooks for further exploration in this field.

PNIPAM-based heteroarm star-graft quarterpolymers: synthesis, characterization and pH-dependent thermoresponsiveness in aqueous media

We report the design of PS_n(P2VP-b-PAA-g-PNIPAM)_n heteroarm star-graft quarterpolymers, the thermoresponsiveness of which is strongly dependent on pH ionic strength, and their macromolecular features, e.g. arm number and grafting density.