Asymmetric macromolecular double-brushes (MDBs) are composed of two different side chains grafted on a linear backbone, possessing distinct assembly behaviors in comparison with conventional amphiphiles, owing to the Janus architecture and combined effects of backbone and hetero double-brushes. Additionally, the introduction of unique functionalities and responsiveness into the self-assembly system of MDBs endows extra opportunities to pursue morphologic diversity and intriguing properties. Herein, we report the synthesis of Janus-like MDBs of polyacrylate-g-poly(6-(4-butyl-4′-oxyazobenzene) hexyl acrylate)/poly(ethylene oxide) (PA-g-PAzo/PEO), in which hydrophilic PEO and hydrophobic PAzo brushes were grafted using the combination of concurrent ATRP and click reaction. Due to the special Janus topology and inter/intramolecular association of pendant azobenzene groups, amphiphilic PA-g-PAzo/PEO self-assembled into multimolecular rod and spindle-like aggregates. It is interesting that a transition of spindle-toroid-spindle was observed upon the alternative irradiation between UV and visible light, which is ascribed to the trans-to-cis isomerization of azobenzene molecular brushes. To our best knowledge, this is the first time that azobenzene-containing MDBs enable the fabrication of distinctive self-assembled morphologies and photoinduced toroid formation. The controlled synthesis of MDBs with unique functionalities and subsequent development of their structure–property relationships would shed light on the design and optimization of bottlebrush-based nanomaterials.
Hierarchical self-assembly is one of the most effective approaches to fabricate nature-inspired materials with subtle nanostructures.W er eport ad istinct hierarchical self-assembly process of molecular double brushes (MDBs) with each graft site carrying ap oly(azobenzene-acrylate) (PAzo)c hain and ap oly(ethylene oxide) (PEO) chain. Asymmetric tapered worm (ATW) nanostructures with chainend reactivity assembling from the azobenzene-derived MDBs serve as primary subunits to prepare branched supermicelles by increasing water content (C w )inTHF/water.Various natural Antedon-shaped multiarm worm-like aggregates (MWAs) can be created via the particle-particle connection of ATWs. Intriguingly,t he azobenzene moieties undergo trans-cis isomerization upon UV irradiation and further promote am orphology evolution of MWAs.M ultiscale supermicelles comprised of starfish shapes with differing central body and arm morphologies (e.g.,c ompare to the biological specimens Luidia ciliaris and Crossaster papposus) were prepared by manipulating irradiation time.
Hierarchical self-assembly is one of the most effective approaches to fabricate nature-inspired materials with subtle nanostructures.W er eport ad istinct hierarchical self-assembly process of molecular double brushes (MDBs) with each graft site carrying ap oly(azobenzene-acrylate) (PAzo)c hain and ap oly(ethylene oxide) (PEO) chain. Asymmetric tapered worm (ATW) nanostructures with chainend reactivity assembling from the azobenzene-derived MDBs serve as primary subunits to prepare branched supermicelles by increasing water content (C w )inTHF/water.Various natural Antedon-shaped multiarm worm-like aggregates (MWAs) can be created via the particle-particle connection of ATWs. Intriguingly,t he azobenzene moieties undergo trans-cis isomerization upon UV irradiation and further promote am orphology evolution of MWAs.M ultiscale supermicelles comprised of starfish shapes with differing central body and arm morphologies (e.g.,c ompare to the biological specimens Luidia ciliaris and Crossaster papposus) were prepared by manipulating irradiation time.
Molecular brushes (MBs) are a unique type of branched macromolecules which graft polymeric chains onto a linear polymeric backbone densely. Crowded tethered side chains generate strong steric repulsion and force the backbone to stretch out, resulting in a persistent cylindrical shape and low density of entanglements of brushes. Owing to the unique rheological and mechanical properties and self-assembly behaviors, MBs show a great potential in nanotechnology and surface science. Herein, the synthesis of novel MBs of polyacrylate-g-poly(6-(4-butyl-4'-oxyazobenzene)hexylacrylate)/barbituric acid (PA-g-PAzo/Bar) was reported, in which PAzo brushes and hydrogen-bonding barbituric acid were grafted using the combination of concurrent atom transfer radical polymerization (ATRP) and click reaction. MBs-based aggregates change from cylinder to compound micelle by increasing the concentration. It is interesting that morphology transitions of cylinder-to-porous nanosheet and compound micelle-to-pearl-necklace were observed upon UV irradiation, that was ascribed to the trans-to-cis isomerization of PAzo brushes.
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