Light-Enabled Reversible Shape Transformation of Block Copolymer Particles

Abstract

Confined self-assembly of block copolymers (BCPs) is effective to manipulate various shapes of particles. In emulsion confined self-assembly, reversibly light-trigged switchable BCP particles are extremely expected, yet rarely reported. Herein, a novel strategy is developed to realize reversibly light-responsive shape-transformation of BCP particles by constructing functional surfactants with light-active azobenzene (azo) groups in the confined self-assembly of BCPs within emulsion droplet. Ultraviolet and visible lights can reversibly modulate the amphiphilicity and interfacial affinity of the surfactants to different blocks, triggering the reversible microphase structure transformation of BCP particles with high temporal-spatial resolution. We can realize shape and morphological transitions of BCP particles from onion-shaped spherical particles to striped ellipsoids and, ultimately, to inverse onion-like particles by ultraviolet irradiation. More importantly, this shape transformation is reversible by the irradiation of visible light, attributed to the reversible trans–cis isomerization of azo groups. We also demonstrate that the light-triggered shape transformation of BCP particles can be employed in a controllable drug release through a noncontacted and programmed manner, showing promising potential in clinic and biomedicine.

Transformation of Amorphous Nanobowls to Crystalline Ellipsoids Induced by Trans‐Cis Isomerization of Azobenzene

“…The shape transformation of polymeric nanostructures also attracts much attention of scientists, which can change their rheological, optical and physiological properties, [4][5][6] DOI: 10.1002/marc.202200131 facilitating the exploitation of their potentials in diverse applications, including drug delivery, [7] catalysis, [8] antimicrobial, [9,10] imaging, [11] and so forth. Typically, external stimuli such as light, [12][13][14] temperature, [15,16] pH, [17][18][19] and redox [20] are used to trigger the shape transformation of stimuli-responsive polymeric nanostructures. [21] Comparing with other stimuli, light is a non-interventional stimulus and widely used to trigger the morphology and structure transformation, while maintains the physicochemical environment unchanged.…”

Self-Assembly of Homo-Polyarylene Ether Into Reactive Matrix for Fabrication of Hybrid Functional Microparticles

“…However, the wider application of emulsion confinement self-assembly, especially in large-scale production, is still limited by the tedious chemical synthesis of involved block copolymers. In addition, although there are plenty of published works dealing with the morphology modulation of polymeric microparticles by tuning block copolymer backbones structures, surfactants compositions, and concentrations ( Deng et al, 2016 ; Shin et al, 2018 ; Ku et al, 2019 ; Hu et al, 2021 ; Xu et al, 2021 ), the research work involving the post-modification and further application of these polymeric microparticles is still quite limited.…”

Light-Active, Reversibly Shape-Shifting Block Copolymer Particles Using Photo-switchable Au Nanoparticle Surfactants

“…Alternatively, azobenzene-based photoswitches are excellent candidates for developing reversible light-responsive particles. , Upon irradiation, azobenzene undergoes a photoisomerization process between its nonpolar trans- and polar cis- configurations according to the specific wavelength of light. , In addition, most azobenzene-containing molecules are highly stable during their reversible photoswitching cycles relative to other light-responsive moieties, , making them promising to achieve robust and reproducible shape-changing BCP particles. As an example, Zhu et al recently reported an excellent work using azobenzene-based organic molecules for achieving light-responsive BCP particles …”

“…As an example, Zhu et al recently reported an excellent work using azobenzene-based organic molecules for achieving light-responsive BCP particles. 36 Developing photoswitchable inorganic nanoparticles (NPs) in combination with azobenzene can provide additional important benefits for producing shape-changing BCP particles. Importantly, the structural complexity of BCPs can be exploited to confine NPs into desired locations, enhancing or suppressing the expression of the distinct physical properties of inorganic NPs through spatially controlled interactions with other constituents.…”