Host-Guest Interaction Mediated Interfacial Co-Assembly of Cyclodextrin and Bottlebrush Surfactants for Precisely Tunable Photonic Supraballs.

Investigations of host-guest interactions at water-oil (w/o) interfaces are limited in single emulsion systems producing simple self-assembled objects with limited uses. Here, within hierarchically ordered water-in-oil-in-water (w/o/w) multiple emulsion droplets, interfacial self-assembly of (polynorbornene-graft-polystyrene)-block-(polynorbornene-graft-polyethylene glycol) (PNPS-b-PNPEG) bottlebrush block copolymers can be precisely controlled through host-guest interactions. α-Cyclodextrin (α-CD) in the aqueous phase can thread onto PEG side chains of the bottlebrush surfactants adsorbed at the w/o interface, leading to dehydration and collapsed chain conformation of the PEG block. Consequently, spherical curvature of the w/o internal droplets increases with the increased asymmetry of the bottlebrush molecules, producing photonic supraballs with precisely tailored structural parameters as well as photonic bandgaps. This work provides a simple but highly effective strategy for precise manipulation of complex emulsion systems applicable in a variety of applications, such as photonic pigments, cosmetic products, pesticides, artificial cells, etc.

Photonic Pigments of Polystyrene-block-Polyvinylpyrrolidone Bottlebrush Block Copolymers via Sustainable Organized Spontaneous Emulsification.

Prior studies on photonic pigments of amphiphilic bottlebrush block copolymers (BBCPs) through an organized spontaneous emulsification (OSE) mechanism have been limited to using polyethylene glycol (PEG) as the hydrophilic side chains and toluene as the organic phase. Herein, a family of polystyrene-block-polyvinylpyrrolidone (PS-b-PVP) BBCPs are synthesized with PVP as the hydrophilic block. Biocompatible and sustainable anisole is employed for dissolving the obtained BBCPs followed by emulsification of the solutions in water. Subsequent evaporation of oil-in-water emulsion droplets triggers the OSE mechanism, producing thermodynamically stable water-in-oil-in-water (w/o/w) multiple emulsions with uniform and closely packed internal droplet arrays through the assembly of the BBCPs at the w/o interface. Upon solidification, the homogeneous porous structures are formed within the photonic microparticles that exhibit visible structural colors. The pore diameter is widely tunable (150∼314 nm) by changing the degree of polymerization of BBCP (69∼110), resulting in tunable colors across the whole visible spectrum. This work demonstrates useful knowledge that OSE can be generally used in the fabrication of ordered porous materials with tunable internal functional groups, not only for photonic applications, but also offers a potential platform for catalysis, sensing, separation, encapsulation, etc.

Sustainable DNA Data Storage on Cellulose Paper.

DNA is a promising material for high density and long-term archival data storage. In addition to algorithms for encoding digital information into DNA sequences, the DNA writing (chemical synthesis) and reading (DNA sequencing), the preservation of DNA mixtures with high sequence diversity is another critical issue for sustainable, long-term, and large-scale DNA data storage. Here, this work demonstrates a method for low-cost, convenient and sustainable DNA data storage on cellulose paper. A DNA pool comprising thousands of sequences, in which archival data are encoded, is conveniently stored on a cellulose paper with a calculated density as high as 15 TB per mm3 through electrostatic adsorption. This work demonstrates that these digitally encoded DNA pools can be stable for years on the cellulose paper after drying even when directly exposed to air. Furthermore, the reversible electrostatic adsorption enables repeated loading/retrieval of DNA on/off cellulose paper. Therefore, this sustainable DNA preservation on cellulose paper through the convenient electrostatic adsorption exhibits a great advantage in terms of storage capacity and cost that is crucial for practical systems to achieve large-scale and long-time data storage.

Self-Assembly and In Situ Quaternization of Triblock Bottlebrush Block Copolymers via Organized Spontaneous Emulsification for Effective Loading of DNA.

Microspheres bearing large pores are useful in the capture and separation of biomolecules. However, pore size is typically poorly controlled, leading to disordered porous structures with limited performances. Herein, ordered porous spheres with a layer of cations on the internal surface of the nanopores are facilely fabricated in a single step for effective loading of DNA bearing negative charges. Triblock bottlebrush copolymers (BBCPs), (polynorbornene-g-polystyrene)-b-(polynorbornene-g-polyethylene oxide)-b-(polynorbornene-g-bromoethane) (PNPS-b-PNPEO-b-PNBr), are designed and synthesized for fabrication of the positively charged porous spheres through self-assembly and in situ quaternization during an organized spontaneous emulsification (OSE) process. Pore diameter as well as charge density increase with the increase of PNBr content, resulting in a significant increase of loading density from 4.79 to 22.5 ng µg-1 within the spheres. This work provides a general strategy for efficient loading and encapsulation of DNA, which may be extended to a variety of different areas for different real applications.

Precise Tailoring of Polyester Bottlebrush Amphiphiles toward Eco-Friendly Photonic Pigments via Interfacial Self-Assembly.

Biodegradable photonic microspheres with structural colors are promising substitutes to polluting microbeads and toxic dyes. Here, amphiphilic polyester-block-poly(ethylene glycol) bottlebrush block copolymers (BBCPs) with polylactic acid or poly(ϵ-caprolactone) as the hydrophobic block are synthesized and used to fabricate eco-friendly photonic pigments. Molecular parameters of BBCPs, including rigidity and symmetry, are precisely tailored by variation of side chain lengths, which enables effective manipulation of interfacial tension (γ). Organized spontaneous emulsion mechanism is enabled only when γ falls in a suitable range (10.6-14.3 mN m-1 ), producing ordered water-in-oil-in-water multiple emulsions and ordered porous structures. Consequently, highly saturated and tunable structural colors are observed due to coherent light scattering from the porous structures. Such photonic materials are nontoxic as confirmed by careful safety tests using aquatic model organisms.

Interfacial Self-Assembly of Amphiphilic Core-Shell Bottlebrush Block Copolymers Toward Responsive Photonic Balls Bearing Ionic Channels.

Photonic balls can be facilely obtained through interfacial self-assembly of amphiphilic bottlebrush block polymers (BBCPs) within a water-in-oil-in-water (w/o/w) multiple emulsion system, and polystyrene (PS) has been employed as the skeleton of the balls showing no responsive properties. Here, the design and synthesis of core-shell BBCPs are demonstrated with a poly(tert-butyl acrylate)-block-polystyrene (PtBA-b-PS) block copolymer as the hydrophobic side chains and poly(ethylene glycol) as the hydrophilic block. Interfacial self-assembly of the core-shell BBCPs within shrinking droplets produces porous microspheres with full-spectrum structural colors through an organized spontaneous emulsification process. The PtBA core wrapped by PS in the skeleton of the balls can be converted into polyacrylic acid (PAA) forming an ionic channel responsive to pH variations. Consequently, the hydrolyzed photonic balls show different colors under different pH conditions dependent on varying degrees of ionization and hydration of the PAA channel. Reflected colors can be verified using an optical spectrometer, providing an effective strategy for precise pH indication.

Janus Photonic Microspheres with Bridged Lamellar Structures via Droplet-Confined Block Copolymer Co-Assembly.

Artificial self-assembly systems typically exhibit limited capability in creating nature-inspired complex materials with advanced functionalities. Here, an effective co-assembly strategy is demonstrated for the facile creation of complex photonic structures with intriguing light reflections. Two different lipophilic and amphiphilic bottlebrush block copolymers (BCPs) are placed within shrinking droplets to enable a cooperative working mechanism of microphase segregation and organized spontaneous emulsification, respectively. Layer assemblies of the lipophilic BCP and uniform water nanodroplets stabilized by the bottlebrush surfactant are both generated, and co-assembled into a bridged lamellar structure with the alternating arrangement of layers and closely packed nanodroplet arrays. Janus microspheres with diverse dual optical characteristics are successfully fabricated, and reflected wavelengths of light are highly tunable simply by changing the formulation or molecular weight of BCP.

Supersoft Elastic Bottlebrush Microspheres with Stimuli-Responsive Color-Changing Properties in Brine.

Solvent-free supersoft elastomer is highly desirable for building photonic structures with significant stimuli-responsive color changes. We report supersoft elastic porous microspheres with vivid structural colors obtained via self-assembly of amphiphilic bottlebrush block copolymers at the water/oil interface templated by ordered water-in-oil-in-water double emulsions. The porous structure is composed of cross-linked bottlebrush polydimethylsiloxane (PDMS) as the supersoft elastic skeleton and bottlebrush poly(ethylene oxide) (PEO) as the internal responsive layer. The obtained microspheres show large reversible volume changes through well-controlled dehydration or hydration of PEO in response to salt ions in an aqueous environment. As a result, full-spectrum colors are obtained dependent on different salt concentrations. In-situ observation of color reflection of a microsphere indicates a gradual structural transition from the outside to the inside corresponding to migration of water molecules and salt ions. Moreover, rod-like bottlebrush PEO exhibits an anion-induced salting-out behavior different from that of random coil polymers. The significantly responsive behaviors of bottlebrush block copolymer (BBCP) assemblies in the presence of salt ions primarily rely on the supersoft elastic skeleton of the porous structure, providing a facile route to the creation of stimuli-responsive photonic materials by low-cost self-assembly methods.

Rapid Responsive Mechanochromic Photonic Pigments with Alternating Glassy-Rubbery Concentric Lamellar Nanostructures.

Photonic pigment particles prepared via self-assembly have been suffering from their poor mechanical performances; i.e., they can easily be damaged and lose structural color under a compression force. This greatly limits their uses as mechanochromic pigments. Here, a nanoscale concentric lamellar structure of alternating glassy-rubbery microdomains is successfully created within photonic microparticles through a confined self-assembly and photo-cross-linking strategy. The glassy domain is composed of polystyrene, and cross-linked bottlebrush polydimethylsiloxane served as the supersoft elastic domain. The obtained photonic structure not only shows large deformation and visible color changes under a loaded compression force but also rapidly recovers to its original state in less than 1 s (∼0.16 s) upon unloading. Continuously loading-unloading micro compression test indicates that no obvious damage can be identified after 250 cycles, indicating the high durability of the pigments against deformation. These pigments with different reflected colors are simply obtained using bottlebrush block copolymer formulations with tunable weight percentages of polymer additives. The mechanical robust photonic pigments may be useful in many important applications.

Self-Assembled Photonic Microsensors with Strong Aggregation-Induced Emission for Ultra-Trace Quantitative Detection.

Ultratrace quantitative detection based on fluorescence is highly desirable for many important applications such as environmental monitoring or disease diagnosis, which however has remained a great challenge because of limited and irregular fluorescence responses to analytes at ultralow concentrations. Herein the problem is circumvented via local enrichment and detection of analytes within a microsensor, that is, photonic porous microspheres grafted with aggregation-induced emission gens (AIEgens). The obtained microspheres exhibit dual structural and molecular functions, namely, bright structural colors and strong fluorescence. Large fluorescence quenching induced by nitrophenol compounds in an aqueous environment is observed at ultralow concentrations (10-12-10-8 mol/L), enabling quantitative detection at a ppb level (ng/L). This is achieved within a porous structure with good connectivity between the nanopores to improve analyte diffusion, an internal layer of poly(ethylene oxide) (PEO) for analyte enrichment via hydrogen bonding, and homogeneous distribution of AIEgens within the PEO layer for enhanced fluorescence quenching. The fluorescent porous microspheres can be readily obtained in a single step templated by well-ordered water-in-oil-in-water double emulsion droplets with AIE amphiphilic bottlebrush block copolymers as the effective stabilizer.

Oxidation Control of Bottlebrush Molecular Conformation for Producing Libraries of Photonic Structures.

Self-assembly is important for creating photonic structures and structural color is typically tunable by varying the size of building blocks, which are themselves obtained after time-consuming chemical syntheses. The molecular conformation of bottlebrush block copolymers (BBCPs) in solution can be manipulated to create libraries of photonic structures. Amphiphilic BBCPs bearing oxidation-responsive ferrocene groups on the hydrophilic block are used to fabricate porous particles via evaporation-induced self-assembly of water-in-oil-in-water (W/O/W) double emulsions stabilized by the BBCP surfactant. In situ oxidation of the ferrocene groups by hydrogen peroxide at the W/O interface leads to enhanced hydrophilicity, more hydration, and chain extension of the hydrophilic block. Consequently, larger internal water droplets are spontaneously formed, yielding larger pores within the microparticles. The pore diameter is readily tunable from 144 to 301 nm with a single BBCP, thereby generating full-spectrum structural colors. This work provides a straightforward method for fabrication of libraries of photonic pigments in an easy and scalable manner.

Angular-Independent Photonic Pigments via the Controlled Micellization of Amphiphilic Bottlebrush Block Copolymers.

Photonic materials with angular-independent structural color are highly desirable because they offer the broad viewing angles required for application as colorants in paints, cosmetics, textiles, or displays. However, they are challenging to fabricate as they require isotropic nanoscale architectures with only short-range correlation. Here, porous microparticles with such a structure are produced in a single, scalable step from an amphiphilic bottlebrush block copolymer. This is achieved by exploiting a novel "controlled micellization" self-assembly mechanism within an emulsified toluene-in-water droplet. By restricting water permeation through the droplet interface, the size of the pores can be precisely addressed, resulting in structurally colored pigments. Furthermore, the reflected color can be tuned to reflect across the full visible spectrum using only a single polymer (Mn  = 290 kDa) by altering the initial emulsification conditions. Such "photonic pigments" have several key advantages over their crystalline analogues, as they provide isotropic structural coloration that suppresses iridescence and improves color purity without the need for either refractive index matching or the inclusion of a broadband absorber.

Hierarchical Photonic Pigments via the Confined Self-Assembly of Bottlebrush Block Copolymers.

Hierarchical, structurally colored materials offer a wide variety of visual effects that cannot be achieved with standard pigments or dyes. However, their fabrication requires simultaneous control over multiple length-scales. Here we introduce a robust strategy for the fabrication of hierarchical photonic pigments via the confined self-assembly of bottlebrush block copolymers within emulsified microdroplets. The bottlebrush block copolymer self-assembles into highly ordered concentric lamellae, giving rise to a near perfect photonic multilayer in the solid state, with reflectivity up to 100%. The reflected color can be readily tuned across the whole visible spectrum by either altering the molecular weight or by blending the bottlebrush block copolymers. Furthermore, the developed photonic pigments are responsive, with a selective and reversible color change observed upon swelling in different solvents. Our system is particularly suited for the scalable production of photonic pigments, arising from their rapid self-assembly mechanism and size-independent color.

Photonic Resins: Designing Optical Appearance via Block Copolymer Self-Assembly.

Despite a huge variety of methodologies having been proposed to produce photonic structures by self-assembly, the lack of an effective fabrication approach has hindered their practical uses. These approaches are typically limited by the poor control in both optical and mechanical properties. Here we report photonic thermosetting polymeric resins obtained through brush block copolymer (BBCP) self-assembly. We demonstrate that the control of the interplay between order and disorder in the obtained photonic structure offers a powerful tool box for designing the optical appearance of the polymer resins in terms of reflected wavelength and scattering properties. The obtained materials exhibit excellent mechanical properties with hardness up to 172 MPa and Young's modulus over 2.9 GPa, indicating great potential for practical uses as photonic coatings on a variety of surfaces.

Rapid, Large-Area Synthesis of Hierarchical Nanoporous Silica Hybrid Films on Flexible Substrates.

We report a simple strategy for the creation of large-area nanoporous hybrid films of silica, carbon, and gold on polyethylene terephthalate via photothermal processing. This method enables the selective heating of light-absorbing thin films on low-temperature substrates using sub-millisecond light pulses generated by a xenon flash lamp. The film contains gold nanoparticles as the nanoheaters to convert light energy to heat, a sacrificial block copolymer surfactant to generate mesopores, and cross-linked polyhedral oligomeric silsesquioxane as the silica source to form the skeleton of the porous structure. Hierarchical porous structures are achieved in the films after photothermal treatment, with uniform mesopores (44-48 nm) on the surface and interconnected macropores (>50 nm) underneath resulting from a foaming effect during release of gaseous decomposition products. The loading of gold nanoparticles is up to 43 wt % in the product, with less than 2 wt % organic residue. This rapid and large-area process for the synthetis of porous structures is compatible with roll-to-roll manufacturing for the fabrication of flexible devices.

Block Copolymer Nanocomposites with High Refractive Index Contrast for One-Step Photonics.

Photonic crystals (PhCs) prepared using the self-assembly of block copolymers (BCPs) offer the potential for simple and rapid device fabrication but typically suffer from low refractive index contrast (Δn ≤ 0.1) between the phase-segregated domains. Here, we report the simple fabrication of BCP-based photonic nanocomposites with large differences in refractive index (Δn > 0.27). Zirconium oxide (ZrO2) nanoparticles coated with gallic acid are used to tune the optical constants of the target domains of self-assembled (polynorbornene-graft-poly(tert-butyl acrylate))-block-(polynorbornene-graft-poly(ethylene oxide)) (PtBA-b-PEO) brush block copolymers (BBCPs). Strong hydrogen-bonding interactions between the ligands on ZrO2 and PEO brushes of the BBCPs enable selective incorporation and high loading of up to 70 wt % (42 vol %) of the ZrO2 nanoparticles within the PEO domain, resulting in a significant increase of refractive index from 1.45 to up to 1.70. Consequently, greatly enhanced reflection at approximately 398 nm (increases of ∼250%) was observed for the photonic nanocomposites (domain spacing = 137 nm) relative to that of the unmodified BBCPs, which is consistent with numeric modeling results using transfer matrix methods. This work provides a simple strategy for a wide range tuning of optical constants of BCP domains, thereby enabling the design and creation of high-performance photonic coatings for various applications. The large refractive index contrast enables high reflectivity while simultaneously reducing the coating thickness necessary, compared to pure BCP systems.

Large-Volume Self-Organization of Polymer/Nanoparticle Hybrids with Millimeter-Scale Grain Sizes Using Brush Block Copolymers.

We report that an exceptionally large volume of highly ordered arrays (single grains) on the order of millimeters in scale can be rapidly created through a unique innate guiding mechanism of brush block copolymers (BBCPs). The grain volume is over 10(9) times larger than that of typical self-assembled linear BCPs (LBCPs). The use of strong interactions between nanoparticles (NPs) and BBCPs enables high loadings of functional materials, up to 76 wt % (46 vol %) in the target domain, while maintaining excellent long-range order. Overall, this work provides a simple method to precisely control the spatial orientation of functionalities at nanometer length scales over macroscopic volumes, thereby enabling the production of hybrid materials for many important applications.

Controlled supramolecular self-assembly of large nanoparticles in amphiphilic brush block copolymers.

To date the self-assembly of ordered metal nanoparticle (NP)/block copolymer hybrid materials has been limited to NPs with core diameters (D(core)) of less than 10 nm, which represents only a very small fraction of NPs with attractive size-dependent physical properties. Here this limitation has been circumvented using amphiphilic brush block copolymers as templates for the self-assembly of ordered, periodic hybrid materials containing large NPs beyond 10 nm. Gold NPs (D(core) = 15.8 ± 1.3 nm) bearing poly(4-vinylphenol) ligands were selectively incorporated within the hydrophilic domains of a phase-separated (polynorbornene-g-polystyrene)-b-(polynorbornene-g-poly(ethylene oxide)) copolymer via hydrogen bonding between the phenol groups on gold and the PEO side chains of the brush block copolymer. Well-ordered NP arrays with an inverse cylindrical morphology were readily generated through an NP-driven order-order transition of the brush block copolymer.

Synthesis and controlled self-assembly of UV-responsive gold nanoparticles in block copolymer templates.

We demonstrate the facile synthesis of gold nanoparticles (GNPs) functionalized by UV-responsive block copolymer ligands, poly(styrene)-b-poly(o-nitrobenzene acrylate)-SH (PS-b-PNBA-SH), followed by their targeted distribution within a lamellae-forming poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer. The multilayer, micelle-like structure of the GNPs consists of a gold core, an inner PNBA layer, and an outer PS layer. The UV-sensitive PNBA segment can be deprotected into a layer containing poly(acrylic acid) (PAA) when exposed to UV light at 365 nm, which enables the simple and precise tuning of GNP surface properties from hydrophobic to amphiphilic. The GNPs bearing ligands of different chemical compositions were successfully and selectively incorporated into the PS-b-P2VP block copolymer, and UV light showed a profound influence on the spatial distributions of GNPs. Prior to UV exposure, GNPs partition along the interfaces of PS and P2VP domains, while the UV-treated GNPs are incorporated into P2VP domains as a result of hydrogen bond interactions between PAA on the gold surface and P2VP domains. This provides an easy way of controlling the arrangement of nanoparticles in polymer matrices by tailoring the nanoparticle surface using UV light.

Impact of antiovarian antibodies (AOA) on ovarian responsiveness in vitro fertilization and embryo transfer.

OBJECTIVE: This study was to investigate the effects of antiovarian antibodies (AOA) on ovarian responsiveness in vitro fertilization and embryo transfer (IVF/ET). METHODS: 233 infertility women younger than 36 years undergone IVF/ET because of single salpingemphraxis were attended in the study, whose fast blood was taken to detect serum AOA by ELISA. Among them there were 35 women with serum AOA positive composed the study group and the other with serum AOA negative composed the control. Ovarian volume, antral follicle number, basal FSH, gonadotropin dosage and recollected oocytes were compared between the 2 groups. RESULT(S): There's no difference in ovarian volume between serum AOA positive group with negative group, P>0.05. The number of antral follicles was less and basal FSH was higher in AOA positive group than in control, P<0.05; what's more, the ampoules of gonadotrophin consumed in AOA positive group exceed significantly in control, and less recollected oocytes in AOA positive group than in control, P<0.01. Of the 233 infertility women, the serum AOA positive rate was 73.08% in the women who got less than 5 recollected oocytes, significantly higher than the other women in the study, P<0.01. CONCLUSION(S): The existing of anti-ovarian antibodies had suppressive effects on the ovarian responsiveness in ovarian stimulation in IVF/ET cycle and on ovarian function. AOA should be detected before IVF/ET to evaluate ovarian responsiveness and further treatment seems necessary.