By introducing strong directed hydrogen bonds to an amphiphilic polymer, we demonstrate that phase transitions from spherical to cylindrical morphologies in aqueous solutions can significantly be shifted to favor the assembly of supramolecular polymer bottlebrushes. In water, a forced self-assembly of polymers into cylindrical structures remains a challenge as the often required hydrophobic shielding induces forces, which tend to minimize the surface area. The herein presented novel benzene trisureas can overcome these limitations due to strong hydrogen bonds and alter the morphology to cylinders despite an unfavorable packing parameter, which dominated the previously reported trisamide analogues. The systematic variation of composition and architecture revealed that a transition to spherical morphologies still occurs, but the phase-transition boundaries appear to be shifted to tolerate larger hydrophilic polymer chains. The strength of the directing interactions appears to be decisive for the shift, though we additionally observed that any restrictions of lateral aggregation can diminish the effect of the directing hydrogen bonds. Overall, the straightforward synthesis and versatile design render the presented systems an interesting blueprint for the development of more advanced supramolecular polymer bottlebrushes and multifunctional nanostructures.

The assembly of polymer building blocks into supramolecular bottlebrushes by non-covalent forces represents an exciting new field of research. This review provides an overview on suitable motifs and requirements for the formation of such structures.

Reactive polymersomes represent av ersatile artificial cargo carrier system that can facilitate an immediate release in response to aspecific stimulus.The herein presented oxidation-sensitive polymersomes feature at ime-delayed release mechanism in an oxidative environment, whichc an be precisely adjusted by either tuning the membrane thickness or partial pre-oxidation. These polymeric vesicles are conveniently prepared by PISA allowing the straightforwarda nd effective in situ encapsulation of cargo molecules,asshown for dyes and enzymes.Kinetic studies revealed acritical degree of oxidation causing the destabilization of the membrane,w hile no release of the cargo is observed beforehand. The encapsulation of glucose oxidase directly transforms these polymersomes into glucose-sensitive vesicles,a ss mall molecules including sugars can passively penetrate their membrane. Considering the ease of preparation, these polymersomes represent av ersatile platform for the confinement and burst release of cargo molecules after ap recisely adjustable time span in the presence of specific triggers,s uch as H 2 O 2 or glucose.

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In contrast to covalent polymer brushes, directional supramolecular forces such as hydrogen bonds or π-π-interactions govern the formation of supramolecular polymer bottlebrushes (SPBs) in a self-assembly process starting from single...

Strong directional hydrogen bonds represent a suitable supramolecular force to drive the one-dimensional (1D) aqueous self-assembly of polymeric amphiphiles resulting in cylindrical polymer brushes. However, our understanding of the kinetics in these assembly processes is still limited. We here demonstrate that the obtained morphologies for our recently reported benzene tris-urea and tris-peptide conjugates are strongly pathway-dependent. A controlled transfer from solutions in organic solvents to aqueous environments enabled a rate-dependent formation of kinetically trapped but stable nanostructures ranging from small cylindrical or spherical objects (<50 nm) to remarkably large fibers (>2 μm). A detailed analysis of the underlying assembly mechanism revealed a cooperative nature despite the steric demands of the polymers. Nucleation is induced by hydrophobic interactions crossing a critical water content, followed by an elongation process due to the strong hydrogen bonds. These findings open an interesting new pathway to control the length of 1D polymer nanostructures.

Reaktive Polymersomen sind ein vielseitiges künstliches Nanotransportsystem, das eine Freisetzungals Reaktion auf einen bestimmten Stimulus ermçglichen kann. Die vorgestellten oxidationsempfindlichen Polymersomen zeigen einen zeitlich verzçgerten Freisetzungsmechanismus in einer oxidativen Umgebung,d er durch Anpassung der Membrandicke oder partielle Voroxidation variierbar ist. Diese polymeren Vesikel werden mittels PISA hergestellt, wodurch eine direkte, effektive In-situ-Einkapselung von Molekülen ermçglicht wird, wie z. B. fürF arbstoffe und Enzyme gezeigt wurde.K inetische Studien ergaben, dass ein kritischer Oxidationsgrad die Destabilisierung der Membran bewirkt, während vorab keine Freisetzung der Ladung erfolgt. Die Einkapselung von Glukoseoxidase verwandelt diese Polymersomen direkt in glukoseempfindliche Vesikel, da kleine Moleküle,wie Zucker, ihre Membran passiv durchdringen kçnnen. Dank der einfachen Herstellung bieten die Polymersomen eine vielseitige Plattform fürd en Einschluss und die Freisetzung von Molekülen nach einer genau einstellbaren Zeitspanne in Gegenwart spezifischer Verbindungen wie H 2 O 2 oder Glukose.

The self-assembly of amphiphilic polymers into worm-like micelles represents a versatile approach to create hydrogels, where interactions and functionalities are widely customizable by the chemistry of the hydrophilic block. However, processing options for such gels remain a bottleneck as fragmentation is often irreversible due to the limited dynamics of the assemblies. We demonstrate here that shear-thinning hydrogels can reversibly be formed by amphiphilic polymers, which assemble into supramolecular polymer nanofibers due to additional directing hydrogen bonds. The addition of bifunctional cross-linkers resulted in robust gels, which feature a surprisingly strong shear-thinning character but recover fully in the absence of shear stress despite the lack of a dynamic exchange of individual building blocks. In addition to increasing the concentration, the strength of the gel can be tuned by varying the content or the length of the bivalent cross-linker. Low viscosities under shear load and the rapid recovery (<5 s) after relief of the strain facilitates an effortless extrusion through even thin needles and subsequent formation of self-supporting structures in a printing process. The polymer covered fiber structure further bestows the gels with an excellent stability in various conditions and good biocompatibility while minimizing cell adhesion. The mesh sizes of the gel allow even large macromolecules to diffuse, but retardation is nevertheless observed for small molecules due to the dense polymer brush structure. This unique set of properties renders these polymer fiber hydrogels a versatile and easily processable scaffold for future applications, for example as an adaptable cell scaffold or injectable drug depots.