Toward transparent nanocomposites based on polystyrene matrix and PMMA-grafted CeO2 nanoparticles

NIR triggered polydopamine coated cerium dioxide nanozyme for ameliorating acute lung injury via enhanced ROS scavenging

Acute lung injury (ALI) is a life threatening disease in critically ill patients, and characterized by excessive reactive oxygen species (ROS) and inflammatory factors levels in the lung. Multiple evidences suggest that nanozyme with diversified catalytic capabilities plays a vital role in this fatal lung injury. At present, we developed a novel class of polydopamine (PDA) coated cerium dioxide (CeO2) nanozyme (Ce@P) that acts as the potent ROS scavenger for scavenging intracellular ROS and suppressing inflammatory responses against ALI. Herein, we aimed to identify that Ce@P combining with NIR irradiation could further strengthen its ROS scavenging capacity. Specifically, NIR triggered Ce@P exhibited the most potent antioxidant and anti-inflammatory behaviors in lipopolysaccharide (LPS) induced macrophages through decreasing the intracellular ROS levels, down-regulating the levels of TNF-α, IL-1β and IL-6, up-regulating the level of antioxidant cytokine (SOD-2), inducing M2 directional polarization (CD206 up-regulation), and increasing the expression level of HSP70. Besides, we performed intravenous (IV) injection of Ce@P in LPS induced ALI rat model, and found that it significantly accumulated in the lung tissue for 6 h after injection. It was also observed that Ce@P + NIR presented the superior behaviors of decreasing lung inflammation, alleviating diffuse alveolar damage, as well as promoting lung tissue repair. All in all, it has developed the strategy of using Ce@P combining with NIR irradiation for the synergistic enhanced treatment of ALI, which can serve as a promising therapeutic strategy for the clinical treatment of ROS derived diseases as well.

Modification of polylactide by poly(ionic liquid)-b-polylactide copolymer and bio-based ionomers: Excellent toughness, transparency and antibacterial property

Polylactide (PLA) is one of the most attractive bioplastics as it can be produced from nontoxic renewable feedstock. However, its inherently poor toughness greatly limits its large-scale application. Cost-effectively toughening PLA without sacrificing its transparency remains a big challenge. We herein prepared an imidazolium-based poly(ionic liquid)-b-PLA copolymer (ILA) and ionomers as toughening agent for PLA through an integrative approach including continuous-monomer-feeding copolymerization, quaternization reaction, ion exchange and inter-ionomers blending. By blending PLA with the ILA and ionomers, we successfully obtained PLA materials with combined features including high toughness, good transparency and antibacterial properties. The effects of regulated ionomer composition and ILA compatibilizer on phase morphology, mechanical properties and transparency of the blends were systematically studied. The optimum formulation (PLA/E12/ILA 60/40/5) shows an impressive transmittance of 89-93 %, high impact strength of 45 kJ/m² and elongation at break at 170 %, which are about 17 and 24 times that of pure PLA, respectively. More interestingly, the presence of imidazolium cation and anion groups endows the blends with attractive antibacterial properties. Ion exchange between ILA copolymer and the imidazolium-containing ionomeric system leads to a synergistic effect of compatibilization and efficient toughening, providing a new strategy for develop high performance PLA materials.

High Photoluminescence Quantum Yield Perovskite/Polymer Nanocomposites for High Contrast X-ray Imaging

A surface modified-CsPbBr₃/polybutylmethacrylate (PBMA) nanocomposite is reported to be a scintillator that enables us to provide a high contrast X-ray image using a common charge-coupled device (CCD) camera. Bis(2-(methacryloyloxy)ethyl) phosphate (BMEP) was employed to alter the ratio of the original ligands on the CsPbBr₃ nanocrystal (NC) surface for optimizing the optical performance of the CsPbBr₃/PBMA nanocomposites. The nanocomposites with a concentration of 0.02 wt % NCs exhibit more than 70% transmittance in the visible region and show a green emission at 515 nm, the fast decay time is 13 ns, while the photoluminescence quantum yield value is 99.2%. Under X-ray excitation, the emission peak wavelength is centered at 524 nm and shows a narrow full width at half-maximum of 26.6 nm; the result nicely matches with the peak quantum efficiency of most commercial CCD/complementary metal oxide semiconductor cameras. The high contrast X-ray image is recorded at a low dose rate of 4.6 μGy_air/s, which enables read out with software. Our results demonstrate that these CsPbBr₃/PBMA nanocomposites have promising application prospects for ionizing radiation detection, especially for X-ray imaging.

Block copolymer-nanodiamond coassembly in solution: towards multifunctional hybrid materials

Polymer-nanodiamond composites are excellent candidates for the fabrication of multifunctional hybrid materials. They integrate polymer flexibility and exceptional properties of nanodiamonds (NDs), such as biocompatibility, mechanical strength, color centers, and chemically-tailored surfaces. However, their development is hindered by the challenge of ensuring that NDs are homogeneously distributed in the composites. Here, we exploit colloidal coassembly between poly(isoprene-b-styrene-b-2-vinyl pyridine) (ISV) block copolymers (BCPs) and NDs to avoid ND self-agglomeration and direct ND spatial distribution. NDs were first air oxidized at 450 °C to obtain stable dispersions in dimethylacetamide (DMAc). By adding ISV into the dispersions, patchy hybrid micelles were formed due to H-bonds between NDs and ISV. The ISV-ND coassembly in DMAc was then used to fabricate nanocomposite films with a uniform sub-50 nm ND distribution, which has never been previously reported for an ND loading (φND) of more than 50 wt%. The films exhibit good transparency due to their well-defined nanostructures and smoothness and also exhibit an improved UV-absorption and hydrophilicity compared to neat ISV. More intriguingly, at a φND of 22 wt%, ISV and NDs coassemble into a network-like superstructure with well-aligned ND strings via a dialysis method. Transmission electron microscopy and dynamic light scattering measurements suggest a complex interplay between polymer-polymer, polymer-solvent, polymer-ND, ND-solvent, and ND-ND interactions during the formation of structures. Our work may provide an important foundation for the development of hierarchically ordered nanocomposites based on BCP-ND coassembly, which is beneficial for a wide spectrum of applications from biotechnology to quantum devices.

Polymer Brush Coating and Adhesion Technology at Scale

Creating strong joints between dissimilar materials for high-performance hybrid products places high demands on modern adhesives. Traditionally, adhesion relies on the compatibility between surfaces, often requiring the use of primers and thick bonding layers to achieve stable joints. The coatings of polymer brushes enable the compatibilization of material surfaces through precise control over surface chemistry, facilitating strong adhesion through a nanometer-thin layer. Here, we give a detailed account of our research on adhesion promoted by polymer brushes along with examples from industrial applications. We discuss two fundamentally different adhesive mechanisms of polymer brushes, namely (1) physical bonding via entanglement and (2) chemical bonding. The former mechanism is demonstrated by e.g., the strong bonding between poly(methyl methacrylate) (PMMA) brush coated stainless steel and bulk PMMA, while the latter is shown by e.g., the improved adhesion between silicone and titanium substrates, functionalized by a hydrosilane-modified poly(hydroxyethyl methacrylate) (PHEMA) brush. This review establishes that the clever design of polymer brushes can facilitate strong bonding between metals and various polymer materials or compatibilize fillers or nanoparticles with otherwise incompatible polymeric matrices. To realize the full potential of polymer brush functionalized materials, we discuss the progress in the synthesis of polymer brushes under ambient and scalable industrial conditions, and present recent developments in atom transfer radical polymerization for the large-scale production of brush-modified materials.

Supertough and Transparent Poly(lactic acid) Nanostructure Blends with Minimal Stiffness Loss

This contribution is an attempt to explore the effectiveness of a series of newly obtained thermoplastic elastomers (TPEs) as a toughening agent for modifying poly(lactic acid) (PLA). The TPEs, including ionically modified isotactic polypropylene-graft-PLA (iPP-g-PLA) copolymers with explicit graft length, graft density, and ionic group content, and an iPP-g-PLA copolymer with a very high molecular weight and explicit graft density, were elaborately designed and synthesized. The semicrystal or rubbery copolymer backbone originated from iPP was designed to improve the toughness and maintain a relatively high strength, while the grafted PLA side chain was to ensure a high level of compatibility with the PLA matrix. To obtain further enhancement in interfacial reinforcement, the imidazolium-based ionic group was also added during graft onto reaction. All of these graft copolymers were identified with randomly distributed PLA branches, bearing a very high molecular weight ((33-398) × 10⁴) and very high PLA content (57.3-89.3 wt %). Unprecedentedly, with a very small amount of newly designed TPE, the modified PLA blends exhibited a significantly increased elongation at break (up to about 190%) and simultaneously retained the very high stiffness and excellent transparency. The nanometer-scale phase-separated particles with good compatibility and refractive index matching to the PLA matrix were demonstrated to play a crucial role in the excellent performance. The findings suggested that the newly designed iPP-g-PLA copolymers are very economic, promising, and effective modifying agents for developing highly transparent and tough PLA-based sustainable materials.

The synthesis of monodispersed M-CeO2/SiO2nanoparticles and formation of UV absorption coatings with them

CeO₂/polymer nanoparticles have drawn considerable attention for their excellent UV absorption properties. However, many challenges still exist in the successful incorporation of ceria into the polymer matrix for the easy agglomeration and photocatalytic activity of CeO₂ nanoparticles. Herein, we address these issues by constructing three-layer structured nanoparticles (M-CeO₂@SiO₂) and incorporating them into a polymer matrix through a mini-emulsion polymerization process. During this process, small-sized nano-ceria became uniformly anchored on the surfaces of monodisperse silica particles first, and then the particles were coated with an MPS/SiO₂ shield. The morphology and dispersion of the nanoparticles were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The performance of the hybrid films was characterized using UV-vis absorption spectroscopy (UV-vis) and water contact angle (WCA) measurements. Results showed that the M-CeO₂@SiO₂ nanoparticles exhibited a three-layer structure with a mean diameter of 360 nm, and they possess good compatibility with acrylic monomers. After the addition of M-CeO₂@SiO₂, hybrid films exhibited enhanced UV absorption capacity as expected, accompanied by an obvious improvement in hydrophobicity (the water contact angle increased from 84.2° to 98.2°). The results showed that the hybrid films containing M-CeO₂@SiO₂ particles possess better global performance as compared with those containing no particles.

Herein, we report the synthesis of monodispersed M-CeO₂/SiO₂ nanoparticles and their use in the construction of a UV absorption coating.

Synthesis and characterization of cellulose acetate naphthoate with good ultraviolet and chemical resistance

Commercial cellulose diacetate with a degree of substitution (DS) of 2.45 was partly deacetylated to cellulose acetate (CA) with different DSs by acid-catalyzed hydrolysis and then reacted with 1-naphthoyl chloride (NpCl) to synthesize CA naphthoate (CANp). Fourier transform infrared and 1H-NMR were used to characterize the chemical structure of CANp. The DS of naphthoate moiety (DSCANp) could be varied from 0.18 to 0.98 by adjusting the molar ratio of –OH in CA unit to NpCl, the DS of CA (DSCA), and the reaction time and temperature. When DSCA was 2.01 and the molar ratio was 1:6, the maximum DSCANp of the product was achieved after a reaction at 80°C for 2 h. With the increase of DSCANp, the thermal stability decreased slightly whereas the anti-ultraviolet property was enhanced. Moreover, the obtained films containing CANp exhibited good ultraviolet resistance as well as chemical resistance.

Photochemical synthesis of CeO2 nanoscale particles using sodium azide as a photoactive material: effects of the annealing temperature and polyvinylpyrrolidone addition

The size of CeO₂ nanoparticles can be controlled by VUV irradiation time and post annealing temperature.

Superhydrophobic Au/polymer nanocomposite films via AACVD/swell encapsulation tandem synthesis procedure

A synthetic route is presented for creating well-attached Au/polymer nanocomposite thin films on glass which exhibit superhydrophobicity.

Null Extinction of Ceria@silica Hybrid Particles: Transparent Polystyrene Composites

Scattering of light in optical materials, particularly in composites based on transparent polymer and inorganic pigment nanoparticles, is a chronic problem. It might originate mainly from light scattering because of a refractive index mismatch between the particles and transparent polymer matrix. Thus, the intensity of light is rapidly diminished and optical transparency is reduced. Refractive index matching between the pigment core and the surrounding transparent matrix using a secondary component at the interface (shell) has recently appeared as a promising approach to alter light scattering. Here, CeO2 (ceria) nanoparticles with a diameter of 25 nm are coated with a SiO2 (silica) shell with various thicknesses in a range of 6.5-67.5 nm using the Stöber method. When the hybrid core-shell particles are dispersed into transparent polystyrene (PS), the transmission of the freestanding PS composite films increases over both the ultraviolet (UV) and visible region as the shell thickness increases particularly at 37.5 nm. The increase of transmission can be attributed to the reduction in the scattering coefficient of the hybrid particles. On the other hand, the particles in tetrahydrofuran (THF) absorb over UV and the intensity of absorption shows a systematic decrease as the shell thickness increases. Thus, the silica shell suppresses not only the scattering coefficient but also the molar absorptivity of the core ceria particles. The experimental results regarding the target shell thickness to develop low extinction (scattering + absorption) composites show a qualitative agreement with the predictions of Effective Medium Theory.

Enabling low amounts of YAG:Ce(3+) to convert blue into white light with plasmonic Au nanoparticles

We report a new strategy to directly attach Au nanoparticles onto YAG:Ce(3+) phosphor via a chemical preparation method, which yields efficient and quality conversion of blue to yellow light in the presence of a low amount of phosphor. Photoluminescent intensity and quantum yield of YAG:Ce(3+) phosphor are significantly enhanced after Au nanoparticle modification, which can be attributed to the strongly enhanced local surface electromagnetic field of Au nanoparticles on the phosphor particle surface. The CIE color coordinates shifted from the blue light (0.23, 0.23) to the white light region (0.30, 0.33) with a CCT value of 6601 K and a good white light CRI value of 78, which indicates that Au nanoparticles greatly improve the conversion efficiency of low amounts of YAG:Ce(3+) in WLEDs.

High-transparency polymer nanocomposites enabled by polymer-graft modification of particle fillers

The role of polymeric ligands on the optical transparency of polymer-matrix composites is analyzed by evaluating the effect of surface modification on the scattering cross-section of particle fillers in uniform particle dispersions. For the particular case of poly(styrene-r-acrylonitrile)-grafted silica particles embedded in poly(methyl methacrylate), it is shown that the tethering of polymeric chains with appropriate optical properties (such as to match the effective refractive index of the brush particle to the embedding matrix) facilitates the reduction of the particle scattering cross-section by several orders of magnitude as compared to pristine particle analogues. The conditions for minimizing the scattering cross-section of particle fillers by polymer-graft modification are established on the basis of effective medium as well as core-shell Mie theory and validated against experimental data on uniform liquid and solid particle dispersions. Effective medium theory is demonstrated to provide robust estimates of the "optimum polymer-graft composition" to minimize the scattering cross-section of particle fillers even in the limit of large particle dimensions (comparable to the wavelength of light). The application of polymer-graft modification to the design of large (500 nm diameter) silica particle composites with reduced scattering cross-section is demonstrated.

Thermal dewetting behavior of polystyrene composite thin films with organic-modified inorganic nanoparticles

The thermal dewetting of polystyrene composite thin films with oleic acid-modified CeO2 nanoparticles prepared by the supercritical hydrothermal synthesis method was investigated, varying the nanoparticle concentration (0-30 wt %), film thickness (approximately 50 and 100 nm), and surface energy of silanized silicon substrates on which the composite films were coated. The dewetting behavior of the composite thin films during thermal annealing was observed by an optical microscope. The presence of nanoparticles in the films affected the morphology of dewetting holes, and moreover suppressed the dewetting itself when the concentration was relatively high. It was revealed that there was a critical value of the surface energy of the substrate at which the dewetting occurred. In addition, the spatial distributions of nanoparticles in the composite thin films before thermal annealing were investigated using AFM and TEM. As a result, we found that most of nanoparticles segregated to the surface of the film, and that such distributions of nanoparticles contribute to the stabilization of the films, by calculating the interfacial potential of the films with nanoparticles.

Shape-controlled synthesis and catalytic application of ceria nanomaterials

Because of their excellent properties and extensive applications, ceria nanomaterials have attracted much attention in recent years. This perspective provides a comprehensive review of current research activities that focus on the shape-controlled synthesis methods of ceria nanostructures. We elaborate on the synthesis strategies in the following four sections: (i) oriented growth directed by the crystallographic structure of cerium-based materials; (ii) oriented growth directed by the use of an appropriate capping reagent; (iii) growth confined or dictated by various templates; (iv) other potential methods for generating CeO(2) nanomaterials. In this perspective, we also discuss the catalytic applications of ceria nanostructures. They are often used as active components or supports in many catalytic reactions and their catalytic activities show morphology dependence. We review the morphology dependence of their catalytic performances in carbon monoxide oxidation, water-gas shift, nitric oxide reduction, and reforming reactions. At the end of this review, we give a personal perspective on the probable challenges and developments of the controllable synthesis of CeO(2) nanomaterials and their catalytic applications.

Directed polystyrene/poly(methyl methacrylate) phase separation and nanoparticle ordering on transparent chemically patterned substrates

We investigate the surface-directed phase separation of spin-coated polystyrene/poly(methyl methacrylate) (PS/PMMA) blends on prepatterned octadecyltrichlorosilane (OTS)-glass substrates under various experimental conditions. As a result of tandem processes of spinodal decomposition and selective wetting of polymer components during spin-coating, low-energy OTS stripes and high-energy glass surfaces laterally arrange the phase-separated polymers according to the chemical pattern on the substrate. Optimal pattern replication was achieved when the length scale of phase separation, controlled via the polymer concentration of the spin-coating solution, matched the smallest feature dimension in a striped chemical pattern possessing two alternating distances between stripes. It was also shown that polymer blend patterns were most closely registered with the underlying substrate when the PS/PMMA composition ratio (30/70, w/w) matched the areal fraction of OTS on the glass surface (∼30%). The influence of solvents demonstrated that a solvent with a relatively low volatility, such toluene, was required for patterning so that domain feature sizes were able to coarsen to the size of the patterned features before film vitrification. As well, we showed that the technique and optimized conditions developed in this study could be applied to pattern photoluminescent CdS quantum dots into microscale arrays of parallel lines via spin-coating onto transparent OTS-glass substrates.