Synthesis of polymeric janus nanoparticles and their application in surfactant-free emulsion polymerizations

Abstract

A robust and simple synthesis of nano-size oblate to dumbbell shaped polymeric anisotropic particles using RAFT mediated emulsion polymerization is presented. The particle synthesis relies on the property that monomer swollen cross-linked polymer seed particles shrink and expel some of the monomer when heated. Thus, upon heating for polymerization, some of the swelling monomer is expelled and subsequently polymerizes to form a bulge on the side of the original crosslinked seed particle. The shape of the bulge, and the degree of contact that the expelled monomer maintains with the original seed particle, is controlled by controlling the wettability of the seed surface by the expelled monomer. Very small monodisperse cross-linked polymer particles are initially prepared by RAFT mediated emulsion polymerization, then swollen with monomer and further polymerized to form anisotropic particles with a long dimension as little as 25 nm. Both the shape of the anisotropic bulge and the polymer composition, of each end of the final Janus nanoparticle can be finely controlled. The surface active properties of the Janus nanoparticles are demonstrated by their ability to contribute as stabilizers and influence particle formation in a surfactant free ab-initio emulsion polymerization. The method provides a simple and reproducible process for the production of Janus colloidal nanoparticles readily achievable in a normal latex plant where batch size would be limited only by the size of the reactor.

Biodistribution and Clearance of Stable Superparamagnetic Maghemite Iron Oxide Nanoparticles in Mice Following Intraperitoneal Administration

“…We previously reported that our s-SPIONs are highly stable and well dispersed in fresh human red blood cells [44]. The prolonged stability of s-SPIONs in vitro under physiological conditions is favorable for potential biomedical applications.…”

In situ polarity functionalization and properties of styrenic triblock copolymers synthesized via RAFT emulsion polymerization

“…The in situ polarity functionalization of SBCs can be probably realized by RAFT (reversible addition‐fragmentation chain transfer) emulsion polymerization technique due to its advantages of the strong block designability and the great tolerance for polar monomer . At present, the polymerization mechanism, emulsion stability, and molecular weight controllability of RAFT emulsion polymerization have been widely investigated, which gives a deep comprehension over RAFT mechanism and process.…”

Tunable and noncytotoxic PET/SPECT-MRI multimodality imaging probes using colloidally stable ligand-free superparamagnetic iron oxide nanoparticles

“…11,24 Our recent publication further demonstrated that these sterically stabilized SPIONs were highly stable and well dispersed after being mixed with fresh human red blood cells. 25 This work presents a robust aqueous-based production of multimodality PET/SPECT-MRI probes on single core superparamagnetic iron oxide (maghemite γ-Fe 2 O 3 ) nanoparticles (SPIONs). Two types of sterically stabilized SPIONs are used in this study: 10 nm diameter (small core) and 25 10,11 This potentially offers better negative MRI contrast agents than all commercially and clinically available samples of similar core sizes.…”

“…25 This work presents a robust aqueous-based production of multimodality PET/SPECT-MRI probes on single core superparamagnetic iron oxide (maghemite γ-Fe 2 O 3 ) nanoparticles (SPIONs). Two types of sterically stabilized SPIONs are used in this study: 10 nm diameter (small core) and 25 10,11 This potentially offers better negative MRI contrast agents than all commercially and clinically available samples of similar core sizes. Ligand-free radiolabeling, which was developed recently for commercially available iron oxide nanoparticles with PET radiotracers, 26,27 is applied to incorporate metal ions of Co, Ga, and Cu as models for PET/SPECT radiotracers.…”