Encapsulation of Gibbsite Platelets With Free Radical and Controlled Radical Emulsion Polymerization Approaches, a Small Review

Abstract

Summary: Water-borne anisotropic polymer-Gibbsite latex particles were prepared by a conventional and an atom transfer radical polymerisation (ATRP) based starvedfeed emulsion polymerisation without any chemical modification of the platelet surface. Anionic co-oligomers, synthesised via ATRP, were used in both approaches. In the conventional-based route charged co-oligomer acted as stabiliser for the initial platelets and the latex particles formed. In case of an ATRP-based approach the co-oligomer not only served as stabiliser, but also as a macroinitiator for Activator ReGenerated by Electron Transfer (ARGET) ATRP-based starved-feed emulsion polymerisation. Cryo-TEM characterization of the resulting nanocomposites showed successfully encapsulated platelets in the conventional-based approach and a "muffin-like" morphology in the ATRP-based one.

A Roadmap towards Successful Nanocapsule Synthesis via Vesicle Templated RAFT-Based Emulsion Polymerization

“…The interplay of kinetics and thermodynamics is paramount in determining the resulting morphology [8]. This was also shown in a parallel approach, utilizing Atom Transfer Radical Polymerization (ATRP) instead of RAFT, which was investigated for Gibbsite encapsulation [9,10,11]. From these studies we learned that the ATRP approach is most likely to result in obtaining equilibrium morphologies, whereas free radical polymerization under slow monomer addition can capture non-equilibrium morphologies.…”

“…The reason is that in ATRP and RAFT, the initial molecular weight is low and building up slowly whereas in free radical polymerization the initial molecular weight is already high from the start. As a result, forming high molecular weight polymer initially, in combination with a low monomer concentration in the growing particles restricts mobility of the molecules and particles and can capture non-equilibrium morphologies [7,8,10]. Alternatively, crosslinking can also capture non-equilibrium morphologies [11].…”