Photochromic Carbon Nanomaterials: An Emerging Class of Light-Driven Hybrid Functional Materials

Photochromic molecules have remarkable potential in memory and optical devices, as well as in driving and manipulating molecular motors or actuators and many other systems using light. When photochromic molecules are introduced into carbon nanomaterials (CNMs), the resulting hybrids provide unique advantages and create new functions that can be employed in specific applications and devices. This review highlights the recent developments in diverse photochromic CNMs. Photochromic molecules and CNMs are also introduced. The fundamentals of different photochromic CNMs are discussed, including design principles and the types of interactions between CNMs and photochromic molecules via covalent interactions and non-covalent bonding such as π-π stacking, amphiphilic, electrostatic, and hydrogen bonding. Then the properties of photochromic CNMs, e.g., in photopatterning, fluorescence modulation, actuation, and photoinduced surface-relief gratings, and their applications in energy storage (solar thermal fuels, photothermal batteries, and supercapacitors), nanoelectronics (transistors, molecular junctions, photo-switchable conductance, and photoinduced electron transfer), sensors, and bioimaging are highlighted. Finally, an outlook on the challenges and opportunities in the future of photochromic CNMs is presented. This review discusses a vibrant interdisciplinary research field and is expected to stimulate further developments in nanoscience, advanced nanotechnology, intelligently responsive materials, and devices.

Trends in the Diversification of the Detergentome

Detergents are amphiphilic molecules that serve as enabling steps for today's world applications. The increasing diversity of the detergentome is key to applications enabled by detergent science. Regardless of the application, the optimal design of detergents is determined empirically, which leads to failed preparations, and raising costs. To facilitate project planning, here we review synthesis strategies that drive the diversification of the detergentome. Synthesis strategies relevant for industrial and academic applications include linear, modular, combinatorial, bio-based, and metric-assisted detergent synthesis. Scopes and limitations of individual synthesis strategies in context with industrial product development and academic research are discussed. Furthermore, when designing detergents, the selection of molecular building blocks, i. e., head, linker, tail, is as important as the employed synthesis strategy. To facilitate the design of safe-to-use and tailor-made detergents, we provide an overview of established head, linker, and tail groups and highlight selected scopes and limitations for applications. It becomes apparent that most recent contributions to the increasing chemical diversity of detergent building blocks originate from the development of detergents for membrane protein studies. The overview of synthesis strategies and molecular blocks will bring us closer to the ability to predictably design and synthesize optimal detergents for challenging future applications.

Multiheaded Cationic Surfactants with Dedicated Functionalities: Design, Synthetic Strategies, Self-Assembly and Performance

Contemporary research concerning surfactant science and technology comprises a variety of requirements relating to the design of surfactant structures with widely varying architectures to achieve physicochemical properties and dedicated functionality. Such approaches are necessary to make them applicable to modern technologies, such as nanostructure engineering, surface structurization or fine chemicals, e.g., magnetic surfactants, biocidal agents, capping and stabilizing reagents or reactive agents at interfaces. Even slight modifications of a surfactant's molecular structure with respect to the conventional single-head-single-tail design allow for various custom-designed products. Among them, multicharge structures are the most intriguing. Their preparation requires specific synthetic routes that enable both main amphiphilic compound synthesis using appropriate step-by-step reaction strategies or coupling approaches as well as further derivatization toward specific features such as magnetic properties. Some of the most challenging aspects of multicharge cationic surfactants relate to their use at different interfaces for stable nanostructures formation, applying capping effects or complexation with polyelectrolytes. Multiheaded cationic surfactants exhibit strong antimicrobial and antiviral activity, allowing them to be implemented in various biomedical fields, especially biofilm prevention and eradication. Therefore, recent advances in synthetic strategies for multiheaded cationic surfactants, their self-aggregation and performance are scrutinized in this up-to-date review, emphasizing their applications in different fields such as building blocks in nanostructure engineering and their use as fine chemicals.

Activation and Inhibition of Isomerization of a Cationic Azobenzene Surfactant in the Large Void Space of Polyglycerol Dendron Micelles

Owing to the unique geometric structure of dendritic amphiphiles with voluminous dendrons, their micelles can harbor a large void space, which provides a new research focus and approach for micellar functionalization. In this work, we used the void space to construct a UV responsive micelle system of the mixed dendritic amphiphile (C₁₂-(G3)₂) and cationic azobenzene surfactant (C4AzoTAB). The synthesized C₁₂-(G3)₂ that possesses double third generation polyglycerol (PG) dendrons and a single alkyl chain is expected to highlight the large void space within the inside of the micelles. Thus, the aims of this work are to achieve the isomerization of C4AzoTAB in situ and to deeply understand the intermolecular interaction in the mixed micelles. The effect of the large void room with a wall decorated with the ether oxygen atoms on the isomerization of C4AzoTAB was studied by isomerization kinetics, conductivity measurements, isothermal titration calorimetry (ITC), and ¹H NMR and 2D NOESY spectroscopies. The isomerization behavior of C4AzoTAB in C₁₂-(G3)₂ micelles was presented in terms of its kinetic constant, counterionic association, interaction enthalpy, and position and orientation of C4AzoTAB. The results of NMR and conductivity show that the quaternary ammonium group of C4AzoTAB situates on the surface of the mixed micelles with C₁₂-(G3)₂ both before and after UV-irradiation, while the position of azobenzene group in C₁₂-(G3)₂ micelles depends on its conformation. The C₁₂-(G3)₂ micelles can inhibit the UV response of the trans-isomer and activate the thermal relaxation of the cis-isomer, which has a potential application in the field of light-controlled smart nanocarriers.

Recyclable and re-usable smart surfactant for stabilization of various multi-responsive emulsions alone or with nanoparticles

A novel multi-responsive surfactant (abbreviated as N⁺-8P8-N) was synthesized, in which one octyl trimethylamine group (quaternary ammonium) and one octyl dimethylamine group are connected to a benzene ring through ether bonds. This novel surfactant can stabilize conventional oil-in-water (O/W) emulsions alone, and O/W Pickering emulsions and novel oil-in-dispersion emulsions together with oppositely and similarly charged nanoparticles, respectively. In all cases rapid demulsification can be achieved through either pH or CO₂/N₂ triggers, by which the surfactant is reversibly converted between a normal cationic surfactant form (N⁺-8P8-N) and a strongly hydrophilic and surface-inactive bola form (N⁺-8P8-NH⁺). Notably, the bola form N⁺-8P8-NH⁺ dissolves in the aqueous phase alone or together with nanoparticles after demulsification without contamination of the oil phase, and the aqueous phase can be recycled many times triggered by pH or CO₂/N₂ in accordance with the principle of green chemistry. This newly designed re-usable smart surfactant is significant for the development of various temporarily stable emulsions, which are extensively applied in emulsion polymerization, new material synthesis, heterogeneous catalysis and oil transportation.

Structural Diversity of Peptoids: Tube-Like Structures of Macrocycles

Peptoids, or poly-N-substituted glycines, are characterised by broad structural diversity. Compared to peptides, they are less restricted in rotation and lack backbone-derived H bonding. Nevertheless, certain side chains force the peptoid backbone into distinct conformations. Designable secondary structures like helices or nanosheets arise from this knowledge. Herein, we report the copper-catalysed alkyne-azide cycloaddition (CuAAC) of macrocycles to form innovative tube-like tricyclic peptoids, giving access to host-guest chemistry or storage applications. Different linker systems make the single tubes tuneable in size and enable modifications within the gap. An azobenzene linker, which is reversibly switchable in conformation, was successfully incorporated and allowed for light-triggered changes of the entire tricyclic structure.

Non-ionic small amphiphile based nanostructures for biomedical applications

Self-assembly of non-ionic amphiphilic architectures into nanostructures with defined size, shape and morphology has garnered substantial momentum in the recent years due to their extensive applications in biomedicine. The manifestation of a wide range of morphologies such as micelles, vesicles, fibers, tubes, and toroids is thought to be related to the structure of amphiphilic architectures, in particular, the choice of the hydrophilic and hydrophobic parts. In this review, we look at different types of non-ionic small amphiphilic architectures and the factors that influence their self-assembly into various nanostructures in aqueous medium. In particular, we focus on the explored structural parameters that guide the formation of various nanostructures, and the ways these structures can be used in applications ranging from drug delivery to cell imaging.

A new azobenzene-based design strategy for detergents in membrane protein research

Mass spectrometry enables the in-depth structural elucidation of membrane protein complexes, which is of great interest in structural biology and drug discovery. Recent breakthroughs in this field revealed the need for design rules that allow fine-tuning the properties of detergents in solution and gas phase. Desirable features include protein charge reduction, because it helps to preserve native features of protein complexes during transfer from solution into the vacuum of a mass spectrometer. Addressing this challenge, we here present the first systematic gas-phase study of azobenzene detergents. The utility of gas-phase techniques for monitoring light-driven changes of isomer ratios and molecular properties are investigated in detail. This leads to the first azobenzene detergent that enables the native mass spectrometry analysis of membrane proteins and whose charge-reducing properties can be tuned by irradiation with light. More broadly, the presented work outlines new avenues for the high-throughput characterization of supramolecular systems and opens a new design strategy for detergents in membrane protein research.

Dendronised Ni(ii) porphyrins as photoswitchable contrast agents for MRI

Light-responsive contrast agents for magnetic resonance imaging (MRI) based on Ni(ii) porphyrin molecular spin switches have recently been introduced. We present their implementation in water and methanol based gels leading to the first soft materials that are rewritable with light and readable with MRI. Light of two different wavelengths as non-invasive stimuli can be applied to switch MRI contrast on and off, with a high spatiotemporal resolution and without fatigue.

Switchable Solubility of Azobenzene-Based Bolaamphiphiles

The ability to design amphiphiles with predictable solubility properties is of everlasting interest in supramolecular chemistry. Relevant structural parameters include the hydrophobic-hydrophilic balance and structural flexibility. In this work, we investigate the water solubility of azobenzene-based triglycerol bolaamphiphiles (TGBAs). In particular, we analyzed the structural effects of backbone hydrophobicity, flexibility, and cis/trans isomerization on the water solubility of a subset of five TGBAs. This leads to the first example of a non-ionic bolaamphiphile whose water solubility can be changed by irradiation with light. The underlying kinetics were monitored using liquid chromatography and a closer analysis of the underlying aggregation processes provides a mechanistic understanding of the light-driven dissolution process. We anticipate that the results obtained will help to engineer bolaamphiphiles with predictable solution properties in the future.

Switchable Oil-in-Water Emulsions Stabilized by Like-Charged Surfactants and Particles at Very Low Concentrations

A novel CO₂/N₂ switchable n-decane-in-water emulsion was prepared, which is stabilized by a CO₂/N₂ switchable surfactant [ N'-dodecyl- N, N-dimethylacetamidine (DDMA)] in cationic form in combination with positively charged alumina nanoparticles at concentrations as low as 0.01 mM and 0.001 wt %, respectively. The particles do not adsorb at the oil-water interface but remain dispersed in the aqueous phase between surfactant-coated droplets. A critical zeta potential of the particles of ca. +18 mV is necessary for the stabilization of the novel emulsions, suggesting that the electrical double-layer repulsions between particles and between particles and oil droplets are responsible for their stability. By bubbling N₂ into the emulsions, demulsification occurs following transformation of DDMA molecules from the surface-active cationic form to the surface-inactive neutral form and desorption from the oil-water interface. Bubbling CO₂ into the demulsified mixtures, cationic DDMA molecules are re-formed, which adsorb to the droplet interfaces, ensuring stable emulsions after homogenization. Compared with Pickering emulsions and traditional emulsions, the amount of switchable surfactant and number of like-charged particles required for stabilization are significantly reduced, which is economically and environmentally benign for practical applications.

Nonionic Dendritic and Carbohydrate Based Amphiphiles: Self-Assembly and Transport Behavior

Herein, a new series of non-ionic dendritic and carbohydrate based amphiphiles is synthesized employing biocompatible starting materials and studied for supramolecular aggregate formation in aqueous solution. The dendritic amphiphiles 12 and 13 possessing poly(glycerol) [G2.0] as hydrophilic unit and C-10 and C-18 hydrophobic alkyl chains, respectively, exhibit low critical aggregation concentration (CAC) in the order of 10^-5 m and hydrodynamic diameters in the 8-10 nm range and supplemented by cryogenic transmission electron microscopy. Ultraviolet-visible (UV-Vis) and fluorescence spectroscopy suggests the effective solubilization of hydrophobic guests by the self-assembled architectures, with the nanotransporters 12 and 13 possessing the highest encapsulation efficiency of 80.74 and 98.03% for curcumin. Efficient uptake of encapsulated curcumin in adenocarcinomic human alveolar basal epithelial (A549) cells is observed by confocal laser scanning microscopy. Amphiphiles 12 and 13 are non-cytotoxic at the concentrations studied, however, curcumin encapsulated samples efficiently reduce the viability of A549 cells in vitro. Experimental studies indicate the ability of amphiphile 13 to encapsulate 1-anilinonaphthalene-8-sulfonic acid (ANS) and curcumin with binding constant of 1.16 × 105⁵ m^-1 and 1.43 × 10⁶ m^-1 , respectively. Overall, our findings demonstrate the potential of these dendritic amphiphiles for the development of prospective nanocarriers for the solubilization of hydrophobic drugs.

Photoswitchable Janus glycodendrimer micelles as multivalent inhibitors of LecA and LecB from Pseudomonas aeruginosa

The first example of the self-assembly and lectin binding properties of photoswitchable glycodendrimer micelles is reported. Light-addressable micelles were assembled from a library of 12 amphiphilic Janus glycodendrimers composed of variable carbohydrate head groups and hydrophobic tail groups linked to an azobenzene core. Spontaneous association in water gave cylindrical micelles with uniform size distribution as determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS). Trans-cis photoisomerization of the azobenzene dendrimer core was used to probe the self-assembly behaviour and lectin binding properties of cylindrical micelles, revealing moderate-to-potent inhibition of lectins LecA and LecB from Pseudomonas aeruginosa.

Light-induced dynamic shaping and self-division of multipodal polyelectrolyte-surfactant microarchitectures via azobenzene photomechanics

Light-induced shape transformations represent a fundamental step towards the emergence of adaptive materials exhibiting photomechanical behaviours. Although a range of covalent azobenzene-based photoactive materials has been demonstrated, the use of dynamic photoisomerization in mesostructured soft solids involving non-covalent co-assembly has received little attention. Here we prepare discrete micrometre-sized hydrated particles of a hexagonally ordered polyelectrolyte-surfactant mesophase based on the electrostatically induced co-assembly of poly(sodium acrylate) (PAA) and trans-azobenzene trimethylammonium bromide (trans-azoTAB), and demonstrate unusual non-equilibrium substrate-mediated shape transformations to complex multipodal microarchitectures under continuous blue light. The microparticles spontaneously sequester molecular dyes, functional enzymes and oligonucleotides, and undergo self-division when transformed to the cis state under UV irradiation. Our results illustrate that weak bonding interactions in polyelectrolyte-azobenzene surfactant mesophases can be exploited for photo-induced long-range molecular motion, and highlight how dynamic shape transformations and autonomous division can be activated by spatially confining azobenzene photomechanics in condensed microparticulate materials.

CO2/N2 triggered switchable Pickering emulsions stabilized by alumina nanoparticles in combination with a conventional anionic surfactant

Switchable n-decane-in-water Pickering emulsions were prepared using positively charged alumina nanoparticles in combination with a trace amount of the anionic surfactant sodium dodecyl sulfate (SDS) and equal moles of a CO₂/N₂ switchable surfactant.

Non-ionic self-assembling amphiphilic polyester dendrimers as new drug delivery excipients

Solubility enhancement of poorly soluble antibiotics via self-assembling nano systems could be a promising approach to effectively treat bacterial infections in the current scenario of evolving resistant species.

Azobenzenes and catalysis

Azobenzene is the most extensively used class of chromophore in a large variety of applications.

Easy directed assembly of only nonionic azoamphiphile builds up functional azovesicles

We reported that C₁₂OazoE₃OH is a functional molecule which directed assembly in water builds up into functional azovesicles.

Molecularly-defined macrocycles containing azobenzene main-chain oligomers: modular stepwise synthesis, chain-length and topology-dependent properties

Molecularly-defined cyclic azobenzene oligomers were prepared and chain-length and topology-dependent on photoresponsive properties were investigated.

Photoresponsive assemblies of linear-dendritic copolymers containing azobenzene in the dendron interior: the effect of the dendron structure on dye encapsulation and release

Linear-dendritic copolymers show differential dye encapsulation and photoinduced dye release based on the number and positions of azobenzenes in the dendritic backbone as well as substituents on the dendron periphery.

Photoisomerization and optical properties of a subphthalocyanine–azobenzene–subphthalocyanine triad

A novel subPc–AB–subPc triad exhibits on–off switching of the fluorescence emission intensity upon reversible trans ↔ cis photoisomerization of the azobenzene moiety. NMR spectroscopy provides additional evidence for the conformational change.

Supramolecular Architectures of Dendritic Amphiphiles in Water

Dendritic molecules are an exciting research topic because of their highly branched architecture, multiple functional groups on the periphery, and very pertinent features for various applications. Self-assembling dendritic amphiphiles have produced different nanostructures with unique morphologies and properties. Since their self-assembly in water is greatly relevant for biomedical applications, researchers have been looking for a way to rationally design dendritic amphiphiles for the last few decades. We review here some recent developments from investigations on the self-assembly of dendritic amphiphiles into various nanostructures in water on the molecular level. The main content of the review is divided into sections according to the different nanostructure morphologies resulting from the dendritic amphiphiles' self-assembly. Finally, we conclude with some remarks that highlight the self-assembling features of these dendritic amphiphiles.

Temperature-induced vesicle to micelle transition in cationic/cationic mixed surfactant systems

Temperature-induced vesicle to micelle transition (VMT), which has rarely been reported in cationic/cationic mixed surfactant systems, was systemically studied in a didodecyldimethylammonium bromide (DDAB)/dodecyltrimethylammonium chloride (DTAC) aqueous solution. We investigated the effect of temperature on DDAB/DTAC aqueous solutions by means of turbidity, conductivity, cryo-TEM, a UV-vis spectrophotometer, and a steady-state fluorescence spectrometer. It was found that increasing temperature could induce the transformation from the vesicle to the micelle in this cationic/cationic mixed surfactant system. The degree of transformation can be easily controlled by the operation temperature. Additionally, by adjusting the proportion of the mixed cationic/cationic systems and employing cationic surfactants with different chain-lengths, we were able to conclude that the hydrophobic tail length of the surfactant affects the aggregation behavior of cationic/cationic mixed surfactant systems as a function of temperature. It is universal to induce the transformation from the vesicle to the micelle by temperature in cationic/cationic mixed surfactant systems. A possible mechanism for the temperature-induced VMT was proposed based on the experimental results.

Photocontrolled release using one-photon absorption of visible or NIR light

Light is an excellent means to externally control the properties of materials and small molecules for many applications. Light's ability to initiate chemistries largely independent of a material's local environment makes it particularly useful as a bio-orthogonal and on-demand trigger in living systems. Materials responsive to UV light are widely reported in the literature; however, UV light has substantial limitations for in vitro and in vivo applications. Many biological molecules absorb these energetic wavelengths directly, not only preventing substantial tissue penetration but also causing detrimental photochemical reactions. The more innocuous nature of long-wavelength light (>400nm) and its ability at longer wavelengths (600-950nm) to effectively penetrate tissues is ideal for biological applications. Multi-photon processes (e.g. two-photon excitation and upconversion) using longer wavelength light, often in the near-infrared (NIR) range, have been proposed as a means of avoiding the negative characteristics of UV light. However, high-power focused laser light and long irradiation times are often required to initiate photorelease using these inefficient non-linear optical methods, limiting their in vivo use in mammalian tissues where NIR light is readily scattered. The development of materials that efficiently convert a single photon of long-wavelength light to chemical change is a viable solution to achieve in vivo photorelease. However, to date only a few such materials have been reported. Here we review current technologies for photo-regulated release using photoactive organic materials that directly absorb visible and NIR light.

Switchable Pickering emulsions stabilized by silica nanoparticles hydrophobized in situ with a conventional cationic surfactant

A stable oil-in-water Pickering emulsion stabilized by negatively charged silica nanoparticles hydrophobized in situ with a trace amount of a conventional cationic surfactant can be rendered unstable on addition of an equimolar amount of an anionic surfactant. The emulsion can be subsequently restabilized by adding a similar trace amount of cationic surfactant along with rehomogenization. This destabilization-stabilization behavior can be cycled many times, demonstrating that the Pickering emulsion is switchable. The trigger is the stronger electrostatic interaction between the oppositely charged ionic surfactants compared with that between the cationic surfactant and the (initially) negatively charged particle surfaces. The cationic surfactant prefers to form ion pairs with the added anionic surfactant and thus desorbs from particle surfaces rendering them surface-inactive. This access to switchable Pickering emulsions is easier than those employing switchable surfactants, polymers, or surface-active particles, avoiding both the complicated synthesis and the stringent switching conditions.

Self-assembly, photoresponsive behavior and transport potential of azobenzene grafted dendronized polymeric amphiphiles

An azobenzene based light responsive polymeric system was developed to study the transport potential and photo-controlled release of encapsulated guests.

Towards engineering of self-assembled nanostructures using non-ionic dendritic amphiphiles

We have reported on the formation of different self-assembled nanostructures by subtle changes in the structure of non-ionic dendritic amphiphiles.

Online monitoring the isomerization of an azobenzene-based dendritic bolaamphiphile using ion mobility-mass spectrometry

The isomerization process of a new azobenzene-based bolaamphiphile was monitored online using ion mobility-mass spectrometry.

Nonviral gene delivery with dendritic self-assembling architectures

In this review, we outline the concept and applicability of self-assembling dendrimers for gene-delivery applications. Low-molecular-weight, well-defined cationic dendritic arrays which have been modified with hydrophobic domains can form self-organized multivalent systems that have significant advantages over nonassembling, high-molecular-weight/polymeric gene vectors. Particular structural variations have been highlighted with respect to the individual components of the displayed dendritic amphiphiles, namely, the employed amine termini, the hydrophobic segment, the size of the dendritic array, and the integration of special features such as targeting ability and cleavability/degradability, which can all have a crucial effect on gene-transfection efficiencies. Accordingly, the scientific efforts to create new synthetic gene-delivery vectors to act as promising in vivo transfection agents in the future will be presented and discussed here.

Azobenzene–siloxane hybrids with lamellar structures from bridge-type alkoxysilyl precursors

Lamellar azobenzene–siloxane hybrids were prepared by self-directed assembly of three types of precursors where mono-, di- and triethoxysilyl groups are bridged by azobenzene groups with propylene linkers.

Coordination-Induced Spin-State-Switch (CISSS) in water

A water-soluble Ni-porphyrin switches the spin state and proton relaxation time of the surrounding water upon addition of an axial ligand.

A CO2-responsive surface with an amidine-terminated self-assembled monolayer for stimuli-induced selective adsorption

A novel amidine-based bifunctional molecule is synthesized for fabrication of a CO₂-responsive surface. Controlling reversible transition of surface charges and wettability in response to stimuli of dissolved CO₂ in water, the selective adsorption of hydrophobic/hydrophilic molecules can be easily achieved.

Photodegradable polyesters for triggered release

Photodegradable polyesters were synthesized with a photolabile monomer 2-nitrophenylethylene glycol and dioyl chlorides with different lengths. These polymers can be assembled to form polymeric particles with encapsulation of target substances. Light activation can degrade these particles and release payloads in both aqueous solutions and RAW 264.7 cells.

Photoresponsive surface molecularly imprinted poly(ether sulfone) microfibers

In the present study, photoresponsive surface molecularly imprinted poly(ether sulfone) microfibers are prepared via nitration reaction, the wet-spinning technique, surface nitro reduction reaction, and surface diazotation reaction for the selectively photoregulated uptake and release of 4-hydrobenzoic acid. The prepared molecularly imprinted microfibers show selective binding to 4-HA under irradiation at 450 nm and release under irradiation at 365 nm. The simple, convenient, effective, and productive method for the preparation of azo-containing photoresponsive material is also applied to the modification of polysulfone and poly(ether ether ketone). All three benzene-ring-containing polymers show significant photoresponsibility after the azo modification.

Controlled reversible debundling of single-walled carbon nanotubes by photo-switchable dendritic surfactants

Stimulus responsive surfactants based on dendritic glycerol azobenzene conjugates were used to solubilize and debundle single-walled carbon nanotubes in aqueous media. Their debundling property as well as their reaggregation behavior upon irradiation with light was examined and light triggered reversible bundling and precipitation are shown.

Micelle-to-vesicle morphological transition via light-induced rapid hydrophilic arm detachment from a star polymer

Micelle-to-vesicle morphological transition has been achieved by light-induced rapid hydrophilic arm detachment from a star polymer. This provides a remote and clean method to control morphology transition of polymeric assemblies.