Pyridine-functional diblock copolymer nanoparticles synthesized via RAFT-mediated polymerization-induced self-assembly: effect of solution pH

Polymerization-induced self-assembly (PISA) via reversible addition-fragmentation chain transfer (RAFT) polymerization has become widely recognized as a versatile and efficient strategy to prepare complex block copolymer nanoparticles with controlled morphology, size, and surface functionality. In this article, we report the preparation of cationic sterically-stabilized poly(2-vinylpyridine)-poly(benzyl methacrylate) (P2VP-PBzMA) diblock copolymer nanoparticles via RAFT-mediated PISA under aqueous emulsion polymerization conditions. It is demonstrated that the solution pH during PISA has a dramatic effect on the resulting P2VP-PBzMA nanoparticles, as judged by dynamic light scattering (DLS), disc centrifuge photosedimentometry (DCP) and transmission electron microscopy (TEM). Varying the solution pH results in the P2VP stabilizer having different solubilities due to protonation/deprotonation of the pyridine groups. This allows P2VP-PBzMA nanoparticles with tunable diameters to be prepared by altering the DP of the stabilizer (P2VP) and/or core-forming block (PBzMA), or simply by changing the solution pH for a fixed copolymer composition. For example, P2VP-PBzMA nanoparticles with larger diameters can be obtained at higher solution pH as the protonation degree of the P2VP stabilizer has a large effect on both the aggregation of polymer chains during the PISA process, and the resulting behavior of the diblock copolymer nanoparticles. Changing the dispersion pH post-polymerization has a relatively limited effect on particle diameter. Furthermore, aqueous electrophoresis studies indicate that these P2VP-PBzMA nanoparticles had good colloidal stability and high cationic charge (>30 mV) below pH 5 and can be dispersed readily over a wide pH range.

Enabling technologies in polymer synthesis: accessing a new design space for advanced polymer materials

This review discusses how developments in laboratory technologies can push the boundaries of what is achievable using existing polymer synthesis techniques.

Flow mediated metal-free PET-RAFT polymerisation for upscaled and consistent polymer production

A slug flow process has been utilised in conjunction with metal-free photopolymerisation to produce well-defined polymers with outstanding consistency.

Sequence Control as a Powerful Tool for Improving the Selectivity of Antimicrobial Polymers

Antimicrobial polymers appear as a promising alternative to tackle the current development of bacterial resistance against conventional antibiotics as they rely on bacterial membrane disruption. This study investigates the effect of segmentation of hydrophobic and cationic functionalities on antimicrobial polymers over their selectivity between bacteria and mammalian cells. Using RAFT technology, statistical, diblock, and highly segmented multiblock copolymers were synthesized in a controlled manner. Polymers were analyzed by HPLC, and the segmentation was found to have a significant influence on their overall hydrophobicity. In addition, the amount of incorporated cationic comonomer was varied to yield a small library of bioactive macromolecules. The antimicrobial properties of these compounds were probed against pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis), and their biocompatibility was tested using hemolysis and erythrocyte aggregation assays, as well as mammalian cell viability assays. In all cases, diblock and multiblock copolymers were found to outperform statistical copolymers, and for polymers with a low content of cationic comonomer, the multiblock showed a tremendously increased selectivity for P. aeruginosa and S. epidermidis compared to its statistical and diblock analogue. This work highlights the remarkable effect of segmentation on both the physical properties of the materials as well as their interaction with biological systems. Due to the outstanding selectivity of multiblock copolymers toward certain bacteria strains, the presented materials are a promising platform for the treatment of infections and a valuable tool to combat antimicrobial resistance.

RAFT multiblock reactor telescoping: from monomers to tetrablock copolymers in a continuous multistage reactor cascade

Well-defined multiblock copolymers were synthesized via reversible addition-fragmentation chain transfer radical polymerization in a fully continuous multireactor cascade.

Looped flow RAFT polymerization for multiblock copolymer synthesis

A flexible, robust and time-efficient scale-up of multiblock copolymers with low dispersity and high livingness.

Progress in reactor engineering of controlled radical polymerization: a comprehensive review

Controlled radical polymerization (CRP) represents an important advancement in polymer chemistry. It allows synthesis of polymers with well-controlled chain microstructures.

Fast RAFT aqueous polymerization in a continuous tubular reactor: consecutive synthesis of a double hydrophilic block copolymer

Utilizing a continuous tubular reactor, well-defined double hydrophilic block copolymer PSPMA-b-PPEGMA was successfully synthesized with an extremely high monomer conversion in water without handling the intermediate macro-RAFT agent.