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Photomediated RAFT step-growth polymerization was performed with and without the presence of a photocatalyst using a trithiocarbonate-based CTA and a maleimide monomer.

Commercially available N-aromatic substituted bismaleimides were used in RAFT step-growth polymerization with a bifunctional RAFT agent, affording polymers having moderate to high molecular weights.

Demonstrated is the successful A2 + B2 RAFT step-growth polymerization of bis-acrylamides. The synthesized poly(acrylamides) can be degraded by simply adding excess ethanolamine or PBu3.

Some of the main applications for synthetic polymers are found within the medical field (drug delivery, diagnostics, medical imaging). However, preparation of these macromolecules has been limited to those with access to chemistry facilities, potentially delaying biological evaluation. In this work, we aim to address this issue by utilising equipment typically found within a biological lab to establish a protocol for the preparation of well-defined macromolecules via RAFT polymerisation. By exploiting thermocycler technology, libraries of homopolymers, block- and statistical-copolymers were prepared in under 5 minutes per heating cycle using acrylamide monomers with ultrafast RAFT polymerisation. All the polymers prepared had excellent molar mass control and could be generated in under 15 min.

Cationic polymers have been widely employed as gene delivery vectors to help circumvent extracellular and intracellular delivery barriers. Among them, polyethylenimine (PEI) is the most commonly used despite its associated high cytotoxicity. PEI is typically obtained by uncontrolled ring opening polymerisation of aziridine, leading to either linear polymer architectures with only secondary amines, or branched architectures containing primary, secondary, and tertiary amines. In contrast, we describe the preparation of hyperbranched poly(ethylenimine-co-oxazoline) that contains only secondary amines, via a fast thiol–yne based one pot reaction. A small library of these compounds with varying PEI contents was then used to study the effect of polymer architecture on pDNA polyplex formation, cytotoxicity, and in vitro transfection studies with plasmid DNA. Hyperbranched poly(ethylenimine-co-oxazoline) was found to have reduced toxicity compared to the commercial standard 25 000 g mol−1 branched PEI (bPEI), with transfection efficiencies only slightly lower than its bPEI counterpart. Obtained results highlight the importance of the polymer architecture on the transfection efficiency of a gene delivery system, which was demonstrated by excluding other parameters such as molecular weight and charge density.

In this report we demonstrate methanol as an effective degenerative chain transfer agent to control the cationic polymerisation (initiated by triflic acid) of electron rich p-alkoxy-styrenes, such as p-methoxystyrene (p-MOS). Kinetic analysis revealed that an induction period occurs initially during which free cationic polymerisation occurs at low monomer conversion before proceeding through the pseudo first order rate, analogous to the RAFT mechanism. Ethanol and isopropanol also demonstrated excellent control (Đ > 1.30), however, with an apparent increase in experimental molecular weight. Furthermore, methanol controlled polymers were successfully chain extended upon sequential monomer addition, demonstrating the ‘livingness’ of the alcohol mediated cationic polymerisation.

Block copolymers containing an organic arsenical (AsAm) have been synthesised by aqueous SET-LRP. The block copolymers are pH and thermoresponsive, forming nanoparticles in aqueous solution. Under reductive conditions the particles are stabilised through the formation of As–As bonds and stability can be tuned as a function of the AsAm monomer feed.

Living systems are driven by molecular machines that are composed of folded polypeptide chains, which are assembled together to form multimeric complexes. Although replicating this type of system is a longstanding goal in polymer science, the complexity the structures impose is synthetically very challenging, and generating synthetic polymers to mimic the process of these assemblies appears to be a more appealing approach. To this end, we report a linear polymer programmable for stepwise folding and assembly to higher order structures. To achieve this, a diblock copolymer composed of 4-acryloylmorpholine and glycerol acrylate was synthesised with high precision via reversible addition fragmentation chain transfer polymerisation (Đ < 1.22). Both intramolecular folding and intermolecular assembly were driven by a pH responsive cross-linker, benzene-1,4-diboronic acid. The resulting intramolecular folded single chain nanoparticles were well defined (Đ < 1.16) and successfully assembled into a multimeric structure (Dh = 245 nm) at neutral pH with no chain entanglement. The assembled multimer was observed with a spherical morphology as confirmed by TEM and AFM. These structures were capable of unfolding and disassembling either at low pH or in the presence of sugar. This work offers a new perspective for the generation of adaptive smart materials.