Morphology Control of Liposome - RAFT Oligomer Precursors to Complex Polymer Nanostructures

Abstract

Different types of butyl acrylate (BA)-co-acrylic acid (AA) oligomers were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization and mixed with extruded 200 nm dimethyldioctadecylammonium bromide vesicles. The resulting precursor structures form the basis for subsequent vesicle-templated polymerizations. Systematic variations in temperature, pH, oligomer length, and oligomer composition and their effects on precursor morphology were studied. Surprisingly, different morphologies were obtained, including capsules, protruded capsules, solid spheres, and multicompartment structures. For example, capsules and multicompartment structures were found to result from higher AA contents, and protruded capsules and solid particles resulted from lower AA contents. Subsequent chain extension of the RAFT oligomers resulted in polymer nanostructures resembling the precursor morphologies.

Synthesis of polymer-vesicle latex particles through an ATRP-based approach

“…9c-d), the same morphology, as after adsorption, was observed in the final latex particles. These results suggest that the morphology after polymerization is directly influenced by the morphology after adsorption as was previously also reported for RAFT polymerization [26].…”

“…As shown above, the co-oligomer composition and chain length affect the adsorption and the resulting morphology of ATRP macroinitiator stabilized vesicle dispersion. This 6 could potentially affect the polymerization process and the final morphology as was found in RAFT-based vesicle encapsulation studies [25,26]. For that reason, we studied the effect of the co-oligomer composition and chain length on the morphology of the resulting composite latex particle.…”

Vesicle-Templated Polymerization, a Review

“…Seldom is the quantification of the different morphologies in the samples presented. Only recently have Moradi et al. , presented a quantitative analysis of the morphologies leading to more solid and systematic conclusions.…”

“…Although it seems to be a method that distinguishes unpolymerized vesicles from vesicles fortified with polymer, some caution needs to be exerted at the conditions the lysis experiments are performed (e.g., temperature, concentration). More recently, the vesicle-RAFT oligomer precursors that are used for vesicle-templated RAFT polymerization, in most cases, also survived the lysis test at room temperature …”

“…Over the years, it has become more and more evident that the characterization of the resulting morphologies is often challenging, both from the very first papers and the more recent papers . Furthermore, the preparation of the vesicle template itself and intermediates in the case of transcriptive synthesis via the RAFT-oligomer approach and its relation to the final particle morphology only now seem to be better understood. − …”