Multiresponsive Square Hybrid Nanosheets of POSS-Ended Hyperbranched Poly(ether amine) (hPEA)

We demonstrated a novel square hybrid nanosheet with a ultrathin thickness for the first time, which was fabricated by self-assembly of hyperbranched poly­(ether amine) (hPEA526) containing anthracene (AN) moieties and heptaisobutyl polyhedral oligomeric silsesquioxane (POSS). TEM and AFM images reveal that the average edge length and thickness of the hybrid nanosheets formed by <b>HP1</b> is 1.2 ± 0.2 μm and 4.5 ± 0.5 nm, respectively. POSS prefers the ordered crystallized aggregation in the formation of the regular square nanosheets, which is confirmed by WAXD and DSC studies. Moreover, these nanosheets are cross-linked through dimerization of anthracene moieties which makes the nanosheets more stable. The other functional moieties such as naphthalene, pyrene, and dodecane can also be easily introduced into the hybrid nanosheets through the same way. The obtained hybrid nanosheets exhibit the multiresponses to temperature and pH, and their dispersion in water can be controlled by temperature. The fluorescence of the hybrid nanosheets decreases with the increasing temperature and pH. The discovery of the hybrid nanosheets is believed to provide a potential guiding significance on the preparation of the functional nanosheets by self-assembly of polymers

Self-Wrinkling Patterned Surface of Photocuring Coating Induced by the Fluorinated POSS Containing Thiol Groups (F-POSS-SH) as the Reactive Nanoadditive

We here demonstrate a facile approach of one-step to obtain the complex wrinkling patterned surface of the photocuring coating by using thiol and fluorocarbon chains containing POSS (F₂-POSS-SH₆) as reactive nanoadditive. F₂-POSS-SH₆ can self-assemble into the top layer of the UV-curing liquid resin. As a result, the mismatch of shrinkage caused by the different types of photo-cross-linking reaction between the top layer and bulk layer leads to formation of the wrinkling pattern. The characteristic wavelength (λ) and amplitude (<i>A</i>) are linearly dependent on the concentration of F₂-POSS-SH₆. The resulting surface exhibits superlow surface energy (4.1 mN/m) when the concentration of F₂-POSS-SH₆ is only 1%. The feasibility and generality of this approach for the excellent hydrophobic and oleophobic surface will undoubtedly find practical application in photocuring coating with functions such as self-cleaning

Size-Tunable Nanosheets by the Crystallization-Driven 2D Self-Assembly of Hyperbranched Poly(ether amine) (hPEA)

We reported the preparation of uniform square nanosheets with tunable size by the living crystallization-driven 2D self-assembly of hyperbranched poly­(ether amine) capped with heptaisobutyl polyhedral oligomeric silsesquioxane (POSS). The nanosheets of <b>HP1</b> containing both anthracene (AN) and POSS moieties in a solution of 1,4-dioxane and water can be fragmented after the melting of the POSS moieties upon heating and can be regenerated after the recrystallization of POSS moieties, which was confirmed by microdifferential scanning calorimetry (μDSC) and dynamic light scattering (DLS) studies and transmission electron microscopy (TEM) images. The obtained fragmented nanosheets (<b>HP1-NSs</b>) with a relatively small size were used as seeds for the 2D epitaxial living growth of <b>HP1</b> unimers to fabricate uniform square nanosheets with tunable edge lengths from ∼0.5 to ∼4.5 μm, which is dependent on the unimer-to-seed ratio. Furthermore, dual-component nanosheets can also be obtained by random cocrystallization of <b>HP1</b> with another type of hPEA capped with POSS and ferrocene (<b>HP2</b>). This crystallization-driven 2D self-assembly behavior of POSS-capped hPEA might provide potential significance in the preparation of functional nanosheets with different sizes and components, which could be further used as templates for inorganic nanosheets and 2D-platforms for metal nanoparticles

One-Step Interfacial Thiol–Ene Photopolymerization for Metal Nanoparticle-Decorated Microcapsules (MNP@MCs)

We herein reported a one-step strategy to prepare the noble metal nanoparticle-decorated microcapsules (MNP@MCs) through the interfacial thiol–ene photopolymerization. In the presence of amphiphlic polyhedral oligomeric silsesquioxane (POSS) containing thiol groups (PTPS) as a reactive surfactant and trimethylolpropane triacrylate (TMPTA) as a cross-linker, the oil phase of toluene dissolved with a photoinitiator was emulsified into a water phase containing a metal precursor to form an oil-in-water (O/W) emulsion. Upon irradiation of ultraviolet (UV) light, the thiol–ene photoploymerization and photoreduction at the interface of toluene/water lead to the formation of the cross-linked wall and metal nanoparticles, respectively. A series of gold, silver, and platinum nanoparticle-decorated microcapsules (AuNP@MC, AgNP@MC, and PtNP@MC) were prepared through this one-step interfacial thiol–ene photopolymerization and were characterized carefully by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results revealed that the obtained MNP@MCs were 2.2–2.7 μm in diameter with a wall of 40–70 nm in thickness, which was covered with the metal nanoparticles. The size and amount of metal nanoparticles increased with the increasing concentration of the metal precursor in water. Furthermore, the catalyst performance of AuNP@MC was studied by reduction of aromatic nitro compounds and exhibited the enhanced catalytic activity and good stability in the reduction of hydrophobic nitrophenol. It is believed that this robust, convenient, simple strategy based on the one-step interfacial thiol–ene photopolymerization will provide an important alternative to fabricate the functional metal nanoparticle-modified microcapsules

Poly(vinyl alcohol) (PVA)-Enhanced Hybrid Hydrogels of Hyperbranched Poly(ether amine) (hPEA) for Selective Adsorption and Separation of Dyes

The unique selective adsorption of hydrophilic dyes gives the hybrid hydrogels of hyperbranched poly­(ether amine) (SiO_1.5-hPEA-Gels) potential in the separation. We here introduced poly­(vinyl alcohol) (PVA) to enhance the mechanical strength of hybrid hydrogels to extend them into the practical application. A series of PVA-enhanced hybrid hydrogels (PVA@SiO_1.5-hPEA-Gels) were prepared by chemically cross-linking between hydroxyl groups of PVA and trimethoxysilyl groups of hyperbranched poly­(ether amine) (TMS-hPEA) in water. The compress stress of PVA@SiO_1.5-hPEA-Gels increased significantly with the increasing content of PVA. Compared to hybrid hydrogel without PVA, the stress of PVA@SiO_1.5-hPEA-1/2-Gel containing 33% PVA increased hundreds of times. The adsorption behavior of the obtained PVA-enhanced hydrogels to ten hydrophilic dyes was investigated in detail. Regardless of their charge states, PVA@SiO_1.5-hPEA-Gels exhibited the quick adsorption to Ponceau S (PS), Rose Bengal (RB), Orange G (OG), and Ponceau SX (PSX) with a high adsorption capacity (<i>Q</i>_eq) and very slow adsorption of Bismarck brown Y (BY), Methylene Blue trihydrate (MB), and Rhodamine 6G (R6G) with a low adsorption capacity. The adsorption process was found to follow the pseudo-second-order kinetics, and the introduction of PVA has no obvious effect on the adsorption behavior in this study. The big difference in the adsorption to the different dyes is indicative of the selective adsorption of PVA@SiO_1.5-hPEA-Gels to dyes. A methodology of dynamic separation of dye’s mixtures (PS/BY and OG/MB) in water is finally demonstrated by using PVA@SiO_1.5-hPEA-Gels

Multi-Responsive Wrinkling Patterns by the Photoswitchable Supramolecular Network

Multiresponsive reversible wrinkling patterns provide an effective approach to dynamically tuning the properties of surface on-demand to realize a smart surface; however, their fabrication remains challenging. In this study, we report a simple yet robust method to fabricate multiresponsive wrinkles based on a supramolecular polymer network composed of copolymer (P4VP-PS-PnBA) and carboxyl containing anthracene (AN-COOH), which can be cross-linked dynamically through reversible photodimerization of anthracene (AN) and the hydrogen bond between carboxyl and pyridine groups. The wrinkle pattern can be generated and erased selectively by UV radiation of different wavelengths due to reversible dimerization of AN. The resulting wrinkles have an extremely sensitive response to hydrogen chloride (HCl) gas and can be erased by HCl with a concentration of 5 ppm in the atmosphere. The generation/elimination process responsive to light and HCl could be cycled many times without damaging characteristic wrinkles, which enables this dynamic wrinkle pattern to be employed for such potential applications as smart displays and nonink printing

Hybrid Core–Shell Microspheres from Coassembly of Anthracene-Containing POSS (POSS-AN) and Anthracene-Ended Hyperbranched Poly(ether amine) (hPEA-AN) and Their Responsive Polymeric Hollow Microspheres

We demonstrated a novel core–shell microsphere (CSM) fabricated from coassembly of anthracene-ended hyperbranched poly­(ether amine) (hPEA-AN) and anthracene containing polyhedral oligomer silsesquioxane (POSS-AN). The obtained CSMs are cross-linked through photodimerization of anthracene and possess the well-defined core–shell structure according to the images of SEM, TEM, and AFM. The shell of the obtained CSM is comprised of hPEA-AN, while POSS-AN prefers the ordered crystallized aggregation in the core. The size of the obtained CSMs is uniform and tunable. With the increasing content of hPEA-AN in the coassembly, the diameter of CSMs decreased from 930 to 616 nm, while the thickness of shell increased from 95 to 170 nm. Moreover, polymeric hollow microsphere (PHM) was prepared by removing the POSS-AN core of CSM in hydrofluoric acid (HF). The obtained PHM is amphiphilic and fluorescent, and its size is responsive to environmental stimulus such as temperature and pH. PHM can be used in the encapsulation and controlled release of guest molecules. Moreover, the controlled release of guest molecules from PHM can be monitored by itself fluorescence change

Polymerization-Induced Growth of Microprotuberance on the Photocuring Coating

Surface pattern on the nano- and microscale is of great interest due to its special optical effect, which might find potential application in optical devices such as LCD display, packaging of LED chip, and thin-film solar cell. We here developed a facile bottom-up approach to fabricate microprotuberance (MP) on surface by using curable resin via sequential photocuring at room temperature and thermal polymerization at high temperature. The curable resin is composed of random fluorinated polystyrene (PSF) as blinder and trimethylolpropane trimethacrylate (TMPTA) as cross-linker. The polymerization of TMPTA during the annealing process at high temperature induces phase separation between the PSF and TMPTA cross-linked network, resulting in the extrusion of PSF and the formation of protuberance on the surface. The formation mechanism of MP was studied in detail by investigating the effect of annealing time, temperature, thickness of film, and PSF on the size and morphology. MPs with size from one to tens of micrometers were fabricated through this one-pot strategy. Moreover, encapsulation of integrated GaN/InGaN-based LED chip by the cross-linked coating with MP can enhance the light extraction efficiency and light diffusion obviously

Multi-Responsive Wrinkling Patterns by the Photoswitchable Supramolecular Network

Multiresponsive reversible wrinkling patterns provide an effective approach to dynamically tuning the properties of surface on-demand to realize a smart surface; however, their fabrication remains challenging. In this study, we report a simple yet robust method to fabricate multiresponsive wrinkles based on a supramolecular polymer network composed of copolymer (P4VP-PS-PnBA) and carboxyl containing anthracene (AN-COOH), which can be cross-linked dynamically through reversible photodimerization of anthracene (AN) and the hydrogen bond between carboxyl and pyridine groups. The wrinkle pattern can be generated and erased selectively by UV radiation of different wavelengths due to reversible dimerization of AN. The resulting wrinkles have an extremely sensitive response to hydrogen chloride (HCl) gas and can be erased by HCl with a concentration of 5 ppm in the atmosphere. The generation/elimination process responsive to light and HCl could be cycled many times without damaging characteristic wrinkles, which enables this dynamic wrinkle pattern to be employed for such potential applications as smart displays and nonink printing

Responsive Fluorescent Nanorods from Coassembly of Fullerene (C₆₀) and Anthracene-Ended Hyperbranched Poly(ether amine) (AN-hPEA)

We herein demonstrated a novel multiresponsive fluorescent nanorod based on C₆₀, which is fabricated through the versatile coassembly of fullerene C₆₀ and anthracene-ended hyperbranched poly­(ether amine) (AN-hPEA). The supramolecular nanorods (C₆₀@AN-hPEA) can be further cross-linked through photodimerization of anthracene, and the size of the obtained nanorods is 2–12 μm in length and 50–90 nm in diameter. C₆₀@AN-hPEA nanorods are amphiphilic, responsive, and fluorescent. The fluorescence of C₆₀@AN-hPEA nanorods in aqueous solution is responsive to temperature and pH. The C₆₀@AN-hPEA-1/4 nanorods exhibit the interesting temperature-enhanced fluorescence, while the fluorescence intensity of AN-hPEA without C₆₀ decreases with the increasing temperature. Detailed fluorescence study revealed that the temperature-enhanced fluorescence behavior of C₆₀@AN-hPEA-1/4 nanorods might be ascribed to the static quenching of the excited anthracene by C₆₀