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Aqueous self‐assembly of amphiphilic block copolymers form diverse nanostructured morphologies depending on block volume fraction and solvophilicity. Stimuli‐responsive motifs have been combined with self‐assembled micelles to afford spatiotemporal, on‐demand encapsulation and payload release. However, the role of modular polymer architecture (i.e., bottlebrushes) in stimuli‐responsive aqueous self‐assembly is not fully understood. The synthesis, aqueous self‐assembly, and photoirradiation of photolabile, amphiphilic bottlebrush block copolymers is presented herein. Specifically, the efficient photoscission ofo‐nitrobenzene motifs at the junction of a poly(norborneneo‐nitrobenzene polystyrene)‐block‐poly(norbornene polyethylene glycol) diblock bottlebrush side chain and backbone cleaved away hydrophobic polystyrene side chains and artificially increased the volume fraction of poly(ethylene glycol) (f_PEG). In doing so, self‐assembled micelles readily degrade to micelle‐to‐micelle and micelle‐to‐aggregate structures after photoirradiation. Finally, this bottlebrush micelle system is used to demonstrate the efficient encapsulation and stimuli‐responsive release of Nile Red that is monitored by fluorescence spectroscopy and dynamic light scattering. The contribution of this work expands the utility of amphiphilic bottlebrush systems as highly efficient and responsive, hierarchically assembled nanomaterials.

 

Recent developments in the field of polymer vesicles, i.e. polymersomes, have demonstrated that disrupting the equilibrium conditions of the milieu could lead to shape transformation into stable non-spherical morphologies, bringing on-demand shape control to reality and bearing great promise for cell mimicry and a variety of biomedical applications. Here, we studied the self-assembly behavior of glassy amphiphilic triblock copolymers, poly(ethylene glycol)- block -polystyrene- stat -poly(coumarin methacrylate)- block -poly(ethylene glycol) (PEG- b -P(S- stat -CMA)- b -PEG), and their response to various stimuli. By changing the respective molecular weights of both the hydrophobic P(S- stat -CMA) and the hydrophilic PEG blocks, we varied the hydrophobic volume fraction thereby accessing a range of morphologies from spherical and worm-like micelles, as well as polymersomes. For the latter, we observed that slow osmotic pressure changes induced by dialysis led to a decrease in size while rapid osmotic pressure changes by addition of a PEG fusogen led to morphological transformations into rod-like and tubular polymersomes. We also found out that chemically crosslinking the vesicles before inducing osmotic pressure changes led to the vesicles exhibiting hypotonic shock, atypical for glassy polymersomes. We believe that this approach combining the robustness of triblock copolymers and light-based transformations will help expand the toolbox to design ever more complex biomimetic constructs. 

Polymersomes have gained a lot of attention in recent years. Their compartmentalized, hollow nature, stability and ability to transport both hydrophilic and hydrophobic cargo has made them attractive for increasingly complex applications in various fields of biomedicine, catalysis and diagnostics. Progress in these fields would therefore benefit from improvements in polymersome functionality. Recently, morphological control of polymersomes, namely the fabrication of various non‐spherical morphologies, has emerged as a means to enhance the usefulness of the polymersomes. In the present review, we highlight the most topical trends in this field and how these developments and the newly acquired knowledge about their nature can be leveraged towards applications. © 2021 Society of Chemical Industry

 

We introduce a novel synthetic strategy in which high molecular weight comb copolymers with aliphatic side chains can collapse into single-chain nanoparticles (SNCPs) via photodimerization of anthracene under ultraviolet (UV) irradiation. By deliberately selecting hydrophobic comonomers with disparate solvency, we demonstrated that we could control chain collapse. We attribute these results to the formation of pseudo-unimicellar structures, whereby polyisobutylene (PIB) side chains are preferentially solvated, thereby compressing anthracene moieties to form a denser crosslinked core. The control of hydrophobic interactions is a common occurrence in proteins and we believe that our approach can be further extended to achieve multi-compartment SCNPs whereby each section is responsible for a given function. 

We report on the use of visible light as the driving force for the intramolecular dimerization of pendant anthracene groups on a methacrylic polymer to induce the formation of single-chain nanoparticles (SCNPs). Using a 532 nm green laser light source and platinum octaethylporphyrin as a sensitizer, we first demonstrated the use of TTA-UC to dimerize monomeric anthracene, and subsequently applied this concept to dilute poly((methyl methacrylate)- stat -(anthracenyl methacrylate)) samples. A combination of triple-detection size-exclusion chromatography, atomic force microscopy, and UV-visible spectroscopy confirmed the formation of the SCNPs. This report pioneers the use of TTA-UC to drive photochemical reactions in polymeric systems, and showcases the potential for TTA-UC in the development of nanoobjects.