Synthesis of TiO(2)-PMMA nanocomposite: using methacrylic acid as a coupling agent

Preparation of high-performance anti-aging polypropylene by modified nano-TiO2 and calcium sulfate whisker grafted acrylonitrile composite PP

By employing the radical polymerization method, acrylonitrile (AN) was grafted on the surface of nano titanium dioxide (TiO2), and the calcium sulfate whisker (CSW) was modified using the coupling agent KH570 to provide ultraviolet (UV)-absorption capacity. The prepared TiO2-PAN and CSW-PAN materials can improve the anti-aging performance and mechanical properties of polypropylene (PP) and meet the application requirements of high-performance polypropylene. Further, the obtained PP composites show prolonged service life and application scope, which can effectively reduce white waste and avoid both resource waste and environmental pollution.

3D printed denture base material: The effect of incorporating TiO2 nanoparticles and artificial ageing on the physical and mechanical properties

OBJECTIVES

To evaluate the physical and mechanical properties of three-dimensional (3D) printed denture base resin incorporating TiO2 nanoparticles (NPs), subjected to a physical ageing process.

METHODS

Acrylic denture base samples were prepared by a Stereolithography (SLA) 3D printing technique reinforced with different concentrations (0.10, 0.25, 0.50, and 0.75) of silanated TiO2 NPs. The resulting nanocomposite materials were characterized in terms of degree of conversion (DC), and sorption/solubility flexural strength, impact strength, Vickers hardness and Martens hardness and compared with unmodified resin and conventional heat-cured (HC) material. The nanocomposites were reassessed after subjecting them to ageing in artificial saliva. A fractured surface was studied under a scanning electron microscope (SEM).

RESULTS

The addition of TiO2 NPs into 3D-printed resin significantly improved flexural strength/modulus, impact strength, Vickers hardness, and DC, while also slightly enhancing Martens hardness compared to the unmodified resin. Sorption values did not show any improvements, while solubility was reduced significantly. The addition of 0.10 wt% NPs provided the highest performance amongst the other concentrations, and 0.75 wt% NPs showed the lowest. Although ageing degraded the materials' performance to a certain extent, the trends remained the same. SEM images showed a homogenous distribution of the NPs at lower concentrations (0.10 and 0.25 wt%) but revealed agglomeration of the NPs with the higher concentrations (0.50 and 0.75 wt%).

SIGNIFICANCE

The outcomes of this study suggested that the incorporation of TiO2 NPs (0.10 wt%) into 3D-printed denture base material showed superior performance compared to the unmodified 3D-printed resin even after ageing in artificial saliva. The nanocomposite has the potential to extend service life of denture bases in future clinical use.

A PMMA bone cement with improved antibacterial function and flexural strength

A novel non-leaching antibacterial bone cement has been developed and evaluated. An antibacterial furanone derivative was synthesized and covalently coated onto the surface of alumina filler particles, followed by mixing into a conventional poly(methyl methacrylate) bone cement. Flexural strength and bacterial viability were used to evaluate the modified cements. Effects of coated antibacterial moiety content, coated alumina filler particle size and loading were investigated. Results showed that almost all the modified cements showed higher flexural strength (up to 10%), flexural modulus (up to 18%), and antibacterial activity (up to 67% to S. aureus and up to 84% to E. coli), as compared to original poly(methyl methacrylate) cement. Increasing antibacterial moiety and filler loading significantly enhanced antibacterial activity. On the other hand, increasing coated filler particle size decreased antibacterial activity. Increasing antibacterial moiety content and particle size did not significantly affect flexural strength and modulus. Increasing filler loading did not significantly affect flexural modulus but reduced flexural strength. Antibacterial agent leaching tests showed that it seems no leachable antibacterial component from the modified experimental cement to the surrounding environment. Within the limitations of this study, the modified poly(methyl methacrylate) bone cement may potentially be developed into a clinically useful bone cement for reducing in-surgical and post-surgical infection.

Synthesis and Characterization of Antifungal Nanocomposite AgSiO2 Polymethyl Methacrylate

Objectives  Polymethyl methacrylate as the most common material used in denture bases has some problems. The aim of this study was to introduce a new nanocomposite of PMMA to improve flexural strength and antifungal properties.

Materials and Methods  In this experimental study, AgSiO ₂ nanoparticles were prepared, and their characteristics were confirmed by scanning electron microscope and energy dispersive spectroscopy techniques. Then the nanoparticles in the weight ratio of 0.1, 0.3, 0.5, and 0.7% were incorporated to heat-cured PMMA and the control group included no nanoparticles.

To measure the flexural strength before and after thermocycling three-point bending test was used. Eight samples per group with dimensions of 65 × 10 × 2.5 mm were used. Antifungal activity against Candida albicans (PTCC 5027) was investigated through colony count method. Statistical analysis was done by SPSS at significance level of p -value ≤0.05.

Results  The mean flexural strength in groups 0.1, 0.3, and 0.7% was significantly higher than the control. After thermocycling flexural strength of the control group was significantly lower than 0.3 and 0.5% groups. As the concentration of nanoparticles increased the antifungal activity improved ( p < 0.05).

Conclusion  Addition of nanoparticles AgSiO ₂ improved flexural strength and antifungal characteristics of PMMA.

A Highly Controlled Organic-Inorganic Encapsulation Nanocomposite with Versatile Features toward Wearable Device Applications

Ultraviolet-curable polyurethane acrylate (PUA) materials can be used in a number of important applications spanning from microfluidics, surface patterning to wearable technology. For the first time, the potential of encapsulation of modified zirconia (ZrO₂ ) nanoparticles is reported in PUA-based hybrid films aimed to facilitate profoundly enhanced hardness and refractive index. By successfully manipulating the interfacial reaction conditions between ZrO₂ nanoparticles and PUA film, the PUA-based nanocomposites exhibit an ultrahigh hardness of 9 and superior refractive index of 1.64 (589.3 nm). The outcomes obtained pave the way for seamless application of nanozirconia/PUA as a potent encapsulating material that provides structurally morphable, water resistant, and optically transparent light emitting diodes toward wearables devices in healthcare.

Electrospun nanofibers of polyvinylidene fluoride incorporated with titanium nanotubes for purifying air with bacterial contamination

Polyvinylidene fluoride (PVDF) blended with varying concentrations of titanium nanotubes (TNT) was electrospun to result in a nanocomposite filter media. Sandwich structures were obtained by depositing the electrospun fibers between polypropylene (PP) nonwoven sheets. The synthesized tubular TNT was confirmed for its morphology through a transmission electron microscope (TEM). The prepared filter media was analyzed through a scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The effectiveness of the filter media was evaluated through the zone of inhibition and antibacterial activity against E. coli and S. aureus. The Box-Behnken design is experimented with three-level variables, namely areal density of substrate (GSM), electrospinning time (hours), and concentration of TNT (wt%) for investigating the bacterial filtration efficiency through an Andersen sampler. Among other statistical tests (STATs), PVDF + 15 wt% TNT has a bacterial filtration efficiency of 99.88% providing greater potentials upon application for clean air management. It can be noted that the future application of this formulation could be efficient filtration of other microbes and could be used in facemasks to industrial-scale air filters. Graphical abstract.

Metal Oxide-Related Dendritic Structures: Self-Assembly and Applications for Sensor, Catalysis, Energy Conversion and Beyond

In the past two decades, we have learned a great deal about self-assembly of dendritic metal oxide structures, partially inspired by the nanostructures mimicking the aesthetic hierarchical structures of ferns and corals. The self-assembly process involves either anisotropic polycondensation or molecular recognition mechanisms. The major driving force for research in this field is due to the wide variety of applications in addition to the unique structures and properties of these dendritic nanostructures. Our purpose of this minireview is twofold: (1) to showcase what we have learned so far about how the self-assembly process occurs; and (2) to encourage people to use this type of material for drug delivery, renewable energy conversion and storage, biomaterials, and electronic noses.

Synthesis, Optical, Chemical and Thermal Characterizations of PMMA-PS/CeO2 Nanoparticles Thin Film

We report the synthesis of hybrid thin films based on polymethyl methacrylate) (PMMA) and polystyrene (PS) doped with 1%, 3%, 5%, and 7% of cerium dioxide nanoparticles (CeO2 NPs). The As-prepared thin films of (PMMA-PS) incorporated with CeO2 NPs are deposited on a glass substrate. The transmittance T% (λ) and reflectance R% (λ) of PMMA-PS/CeO2 NPs thin films are measured at room temperature in the spectral range (250-700) nm. High transmittance of 87% is observed in the low-energy regions. However, transmittance decreases sharply to a vanishing value in the high-energy region. In addition, as the CeO2 NPs concentration is increased, a red shift of the absorption edge is clearly observed suggesting a considerable decrease in the band gap energy of PMMA-PS/CeO2 NPs thin film. The optical constants (n and k) and related key optical and optoelectronic parameters of PMMA-PS/Ce NPs thin films are reported and interpreted. Furthermore, Tauc and Urbach models are employed to elucidate optical behavior and calculate the band gaps of the as-synthesized nanocomposite thin films. The optical band gap energy of PMMA-PS thin film is found to be 4.03 eV. Optical band gap engineering is found to be possible upon introducing CeO2 NPs into PMMA-PS polymeric thin films as demonstrated clearly by the continuous decrease of optical band gap upon increasing CeO2 content. Fourier-transform infrared spectroscopy (FTIR) analysis is conducted to identify the major vibrational modes of the nanocomposite. The peak at 541.42 cm-1 is assigned to Ce-O and indicates the incorporation of CeO2 NPs into the copolymers matrices. There were drastic changes to the width and intensity of the vibrational bands of PMMA-PS upon addition of CeO2 NPs. To examine the chemical and thermal stability, thermogravimetric (TGA) thermograms are measured. We found that (PMMA-PVA)/CeO2 NPs nanocomposite thin films are thermally stable below 110 °C. Therefore, they could be key candidate materials for a wide range of scaled multifunctional smart optical and optoelectronic devices.

Effect of gamma radiation on the structural, thermal and optical properties of PMMA/Sn0.75Fe0.25S2 nanocomposite

Nanocomposite films of polymethylmethacrylate PMMA with Sn0.75Fe0.25S2 nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Changes in PMMA/Sn0.75Fe0.25S2 nanocomposite (NCP) due to gamma irradiation have been measured. XRD results indicate that the gamma doses of 10–80 kGy cause intermolecular crosslinking that reduces the ordered portion in the NPs. Bonding between the NPs and the host PMMA was confirmed by FTIR. TGA results indicate an enhancement in thermal stability in the NCP films irradiated with doses 20–80 kGy. The optical band gap was reduced from 3.23 to 2.47 eV upon gamma irradiation up to 80 kGy due bonding between the NPs and PMMA which enhanced the amorphous part of the NPs. Finally, the color variation between the blank and irradiated films (ΔE) was determined. Color changes immensely when the PMMA/Sn0.75Fe0.25S2 NCP films are gamma irradiated. Values of ΔE were as much as 31.6 which is an acceptable match in commercial reproduction on printing presses.

Sol-gel synthesis of 2-dimensional TiO2: self-assembly of Ti-oxoalkoxy-acetate complexes by carboxylate ligand directed condensation

2-Dimensional (2D) metal oxides have many potential industrial applications including heterogeneous catalysis, water splitting, renewable energy conversion, supercapacitor applications, biomaterials, gas separation and gas storage. Herein we report a simple and scalable method for the preparation of 2D TiO₂ nanostructures by reaction of titanium isopropoxide with acetic acid at 333 K in isopropanol, followed by calcination at 673 K to remove the organic ligands. Both the products and reaction intermediates have been studied using electron microscopy, X-ray diffraction, N₂ physisorption, nuclear magnetic resonance, thermogravimetric analysis, and X-ray photoelectron, Raman, and infrared spectroscopy. The anisotropic condensation of the planar Ti₆O₄(OⁱPr)₈(OAc)₈ complex is believed to be responsible for the formation of the 2D structure, where OⁱPr and OAc represent isopropoxide and acetate ligands, respectively. This research demonstrates that the metal complexes are promising building blocks for desired architectures, and the self-assembly of an acetate bidentate ligand is a versatile tool for manipulating the shape of final products.

A self-cured glass-ionomer cement with improved antibacterial function and hardness

A novel antimicrobial dental self-cured glass-ionomer cement has been developed and evaluated. Alumina filler particles were covalently coated with an antibacterial polymer and blended into a self-cured glass-ionomer cement formulation. Surface hardness and bacterial viability were used to evaluate the modified cements. Results showed that the modified cements exhibited a significantly enhanced antibacterial activity along with improved surface hardness. Effects of antibacterial moiety content, alumina particle size and loading, and total filler content were investigated. It was found that increasing antibacterial moiety content, particle size and loading, and total filler content generally increased surface hardness. Increasing antibacterial moiety, filler loading and total filler content increased antibacterial activity. On the other hand, increasing particle size showed a negative impact on antibacterial activity. The leaching tests indicate no cytotoxicity produced from the modified cements to both bacteria and 3T3 mouse fibroblast cells.

Synthesizing 1D and 2D metal oxide nanostructures: using metal acetate complexes as building blocks

1D and 2D metal oxide nanostructures are important for potential applications in alternative energy, batteries, supercapacitors, catalysts, biomaterials, and electronic nanodevices. Many current approaches for making the desired nanomaterials require multiple steps, which are often exotic and complex for production on a commercial scale. In contrast, the sol-gel reactions between metal alkoxides and organic acids have emerged as a simple protocol for producing metal oxides and inorganic/organic hybrid materials with a controllable 1D or 2D architecture. Our knowledge of this process continues to evolve through the fundamental goal of designing a desired nanostructure from the corresponding molecular building blocks. Our research was driven by the discovery of various morphologies by fine-tuning the synthesis parameters, such as the reaction temperature and molar ratio of the reactants, as well as switching solvents. These discoveries lead to several quesions: What are the building blocks of the 1D and 2D nanostructures and how does the self-assembly occur? What are the reaction kinetics and the mechanisms of nanostructure formation? What role does the solvent play in the assembly process? What are the effects of reaction temperature and pressure? How can we manipulate the nanostructure-for example, the parallel growth of 1D semiconductors-from a substrate surface? And lastly, what are the industrial applications of macroporous aerogels and xerogels? This minireview will highlight documented research accounts to answer these questions.

An antibacterial dental light-cured glass-ionomer cement with improved hardness

An antibacterial dental light-cured glass-ionomer cement has been developed and evaluated. An antibacterial furanone derivative was synthesized and covalently attached onto the surface of alumina filler particles. The formed antibacterial fillers were then mixed into a light-curable glass-ionomer cement formulation. Surface hardness and bacterial viability were used to evaluate the modified cements. Effects of coated furanone moiety content on the modified fillers, modified alumina filler particle size and loading, and total glass filler content were investigated. Results showed that increasing antibacterial furanone content, modified particle size and loading, and total glass filler content generally increased surface hardness. Increasing furanone moiety, filler loading and total filler content increased antibacterial activity. On the other hand, increasing particle size decreased antibacterial activity. The leaching tests indicate that the modified experimental cement showed no leachable antibacterial component to bacteria and cells.

Recent Developments in Magnesium Metal-Matrix Composites for Biomedical Applications: A Review

Recently, there is a growing interest in developing magnesium (Mg) based degradable biomaterial. Although corrosion is a concern for Mg, other physical properties, such as low density and Young's modulus, combined with good biocompatibility, lead to significant research and development in this area. To address the issues of corrosion and low yield strength of pure Mg, several approaches have been adopted, such as, composite preparation with suitable bioactive reinforcements, alloying, or surface modifications. This review specifically focuses on recent developments in Mg-based metal matrix composites (MMCs) for biomedical applications. Much effort has gone into finding suitable bioactive, bioresorbable reinforcements and processing techniques that can improve upon existing materials. In summary, this review provides a comprehensive overview of existing Mg-based composite preparation and their mechanical and corrosion properties and biological responses and future perspectives on the development of Mg-based composite biomaterials.

Design and Performance of Novel Self-Cleaning g-C3N4/PMMA/PUR Membranes

In the majority of photocatalytic applications, the photocatalyst is dispersed as a suspension of nanoparticles. The suspension provides a higher surface for the photocatalytic reaction in respect to immobilized photocatalysts. However, this implies that recovery of the particles by filtration or centrifugation is needed to collect and regenerate the photocatalyst. This complicates the regeneration process and, at the same time, leads to material loss and potential toxicity. In this work, a new nanofibrous membrane, g-C3N4/PMMA/PUR, was prepared by the fixation of exfoliated g-C3N4 to polyurethane nanofibers using thin layers of poly(methyl methacrylate) (PMMA). The optimal amount of PMMA was determined by measuring the adsorption and photocatalytic properties of g-C3N4/PMMA/PUR membranes (with a different PMMA content) in an aqueous solution of methylene blue. It was found that the prepared membranes were able to effectively adsorb and decompose methylene blue. On top of that, the membranes evinced a self-cleaning behavior, showing no coloration on their surfaces after contact with methylene blue, unlike in the case of unmodified fabric. After further treatment with H2O2, no decrease in photocatalytic activity was observed, indicating that the prepared membrane can also be easily regenerated. This study promises possibilities for the production of photocatalytic membranes and fabrics for both chemical and biological contaminant control.

Multifunctional composite hydrogel bolus with combined self-healing, antibacterial and adhesive functions for radiotherapy

TPU/PAAm hydrogel with excellent mechanical, adhesive, self-healing and antibacterial properties has been successfully prepared as a desirable bolus for radiotherapy.

Grafting Hyperbranched Polymers onto TiO2 Nanoparticles via Thiol-yne Click Chemistry and Its Effect on the Mechanical, Thermal and Surface Properties of Polyurethane Coating

In this study, we proposed a novel and facile method to modify the surface of TiO₂ nanoparticles and investigated the influence of the surface-modified TiO₂ nanoparticles as an additive in a polyurethane (PU) coating. The hyperbranched polymers (HBP) were grafted on the surface of TiO₂ nanoparticles via the thiol-yne click chemistry to reduce the aggregation of nanoparticles and increase the interaction between TiO₂ and polymer matrices. The grafting of HBP on the TiO₂ nanoparticles surface was investigated by means of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) and thermogravimetry analysis (TGA). The thermal and mechanical properties of nanocomposite coatings containing various amounts of TiO₂ nanoparticles were measured by dynamic mechanical thermal (DMTA) and tensile strength measurement. Moreover, the surface structure and properties of the newly prepared nanocomposite coatings were examined. The experimental results demonstrate that the incorporation of the surface-modified TiO₂ nanoparticles can improve the mechanical and thermal properties of nanocomposite coatings. The results also reveal that the surface modification of TiO₂ with the HBP chains improves the nanoparticle dispersion, and the coating surface shows a lotus leaf-like microstructure. Thus, the functional nanocomposite coatings exhibit superhydrophobic properties, good photocatalytic depollution performance, and high stripping resistance.

Patterning of ZnO Quantum Dot and PMMA Hybrids with a Solvent-Assisted Technique

Imprinting of nanoparticle-polymer hybrids has been a challenging task due to the agglomeration of nanoparticles, especially for metal oxides because of their highly hydrophilic and polar surfaces. We hereby report an effective submicron patterning process of ZnO quantum dot/poly(methyl methacrylate) hybrids with a solvent-assisted lithographic technique. Feature sizes down to 250 nm have been achieved with a ZnO content up to 50 vol %, about 10 times higher than the literature-reported inorganic contents. With higher ZnO contents, particles show a tendency to aggregate, and the samples have less flexibility as demonstrated by larger bending radii before failure. The higher ZnO content samples also produce stronger photoluminescence responses. This family of materials has a great potential to be used in flexible optical devices.

Behavior of PMMA Denture Base Materials Containing Titanium Dioxide Nanoparticles: A Literature Review

Titanium dioxide nanoparticles (TiO₂NP) have gained interest in the dental field because of their multiple uses in addition to their antimicrobial effect. One of the applications in dentistry involves the incorporation into poly methyl methacrylate (PMMA) resin. However, there is a lack of evidence on their effects on the behavior of the resulting nanocomposite. Therefore, the present review aims to screen literatures for data related to PMMA/TiO₂ nanocomposite to figure out the properties of TiO₂ nanoparticles, methods of addition, interaction with PMMA resin matrix, and finally the addition effects on the properties of introduced nanocomposite and evidence on its clinical performance. Regardless of the latest research progress of PMMA/TiO₂ nanocomposite, the questionable properties of final nanocomposite and the lack of long-term clinical evidence addressing their performance restrict their wide clinical use. A conclusive connection between nanoparticle size or addition method and nanocomposite properties could not be established.

Smart Textiles Coated with Eco-Friendly UV-Blocking Nanoparticles Derived from Natural Resources

Herein, eco-friendly iron titanate nanoparticles, FeTiO₃ (FT), derived from natural resources (like ilmenite sand) were coated onto cotton fabrics (CF) to develop smart textile with enhanced UV-shielding property. The FT nanoparticles were dispersed in a polyurethane (PU) matrix, and the resulting nanocomposite was coated on CF. In addition, few sandwich architectures were designed by rationally stacking CF coated with PU and FT nanoparticles. The resulting sandwich structures blocked UV rays mainly by absorption. FT nanoparticles were comprehensively characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis, vibrating sample magnetometer, and thermogravimetric analysis. FT was suitably surface-functionalized to enhance the quality of dispersion in PU, thereby facilitating effective coating on CF. The latter was systematically evaluated by microscopic and spectroscopic techniques. In addition, flammability of the coated CF was evaluated and the char was assessed to gain insight into the fire-retardant properties. Interestingly, CF coated with FT exhibited a strong UV-shielding ability in sharp contrast to CF coated with PU. Further, the sandwich architecture consisting of CF with FT and PU resulted in an increase in the ultraviolet-protecting factor value to >50 compared to only PU-coated CF. Our results indicate that the sandwich structure holds excellent promise in the quest of designing smart textiles with enhanced UV shielding.

Titanium Oxide (TiO₂)/Polymethylmethacrylate (PMMA) Denture Base Nanocomposites: Mechanical, Viscoelastic and Antibacterial Behavior

Currently, polymethylmethacrylate (PMMA) is the most popular denture base material. Most fractures of dentures that occur during function are due to its insufficient mechanical strength. The major drawbacks of PMMA are insufficient ductility, strength, and viscoelastic behavior. The purpose of this study was to evaluate a polymethylmethacrylate denture base material modified with TiO₂ nanoparticles in terms of nanomechanical, creep-recovery, and relaxation. Additionally, the effects of addition TiO₂ nanoparticles on the thermal and antimicrobial adhesion behaviors were investigated. Differential scanning calorimetry and thermogravimetric analysis indicated that the effect of small amounts of TiO₂ nanoparticles (1 wt. %, 2 wt. %, and 3 wt. %) on the degradation behavior of PMMA denture bases was insignificant. The nanomechanical test results of the PMMA and PMMA/TiO₂ nanocomposites indicated that the hardness and modulus in the nanoscale range improved due to TiO₂ addition. At a 1200-nm penetration depth, the modulus increased by 10%, 16%, and 29% and hardness increased by 18%, 24%, and 35% with the addition of 1 wt. %, 2 wt. %, and 3 wt. % TiO₂, respectively. Furthermore, the creep-recovery and relaxation behaviors of PMMA were significantly improved due to the addition of TiO₂. The creep strain decreased from 1.41% to 1.06%, 0.66%, and 0.49% with the addition of 1 wt. %, 2 wt. %, and 3 wt. % TiO₂, respectively. The relaxation test results showed that the initial stress under 1% strain improved to 19.9, 21.2, and 22 MPa with the addition of 1 wt. %, 2 wt. %, and 3 wt. % TiO₂, respectively. The improvement in the nanohardness, modulus, creep recovery, and relaxation behavior of PMMA due to the addition of TiO₂ nanoparticles indicated the role of the nanoparticles in increasing the PMMA matrix stiffness by reducing its mobility and free volume. TiO₂ nanoparticles also improved the antimicrobial behavior of PMMA by significantly reducing bacterial adherence with increasing TiO₂ ratio.

Suspension-based imprint lithography of ZnO-PMMA hybrids

Imprint lithography has been explored as a method to transfer arrays of patterned features onto pure polymers and polymer/metallic nanoparticle composites. Despite the success of this method for those materials, it has never been achieved on the sub-micron scale with polymer-oxide particle hybrids. This study patterns ZnO-PMMA (poly(methyl methacrylate)) hybrids via imprint lithography from co-suspensions of PMMA and ZnO nanoparticles in anisole from 1 vol% to 20 vol% ZnO solids loading. ZnO nanoparticles are functionalized with nonanoic acid to disperse the nanoparticles in anisole with dissolved PMMA. The feature fidelity of the patterned arrays decreases with increasing ZnO content, indicating an increase in particle agglomeration as the ZnO particle content increases. Feature size, ZnO content, and ZnO nanoparticle agglomeration are critical factors influencing the photoluminescence (PL) intensity. The ZnO solids loading at a 500 nm feature size needs to be 10 vol% or higher for the enhanced PL response. When the ridge size increases to 1 μm, ZnO solids loading as low as 1 vol% is feasible. This method of lithographic patterning of nanoparticle-polymer suspensions can be applied to a wide variety of hybrid devices and has the potential to open many applications including optical devices and biomedical screening.

Poly(methyl methacrylate) with TiO2 nanoparticles inclusion for stereolitographic complete denture manufacturing - the fututre in dental care for elderly edentulous patients?

OBJECTIVES

The aim of this study was to obtain a Poly(methylmethacrylate) (PMMA)-TiO₂ nanocomposite material with improved antibacterial characteristics, suitable for manufacturing 3D printed dental prosthesis.

METHODS

0.2, 0.4, 0.6, 1, 2.5 by weight% of TiO₂ nanoparticles have been added to the commercially available stereolithographic PMMA material and the obtained nanocomposites have been analyzed using FTIR, SEM and also tested for antimicrobial efficacy against bacterial cultures from Candida species (C. scotti).

RESULTS

SEM images and EDX results highlighted the presence of TiO₂ in PMMA nanocomposites. The elemental composition (EDX) also showed the presence of other fillers included in stereolithographic PMMA solution. FTIR analysis clearly revealed changes in polymeric matrix structure when adding TiO₂ nanoparticles. Sample containing 0.4, 1 and 2.5wt% TiO₂ nanoparticles inhibited the growth of Candida scotti strain in standard conditions according to the toxicity control method (DHA). Increasing quantity of nano-titania has resulted in particles fooling, forming new aggregates instead of the homogenous dispersion of nanoparticles with modified viscosity characteristics and expected lower mechanical parameters.

CONCLUSIONS

Significant improvements in polymer characteristics and nice dispersion of the TiO₂ nanoparticles have been noticed for 0.4wt%, therefore it was used for stereolitographic complete denture prototyping.

CLINICAL SIGNIFICANCE

Incorporation of TiO₂ nanoparticles in PMMA polymer matrix was proved to have antibacterial effects, specifically on Candida species. The newly obtained 0.4% nanocomposite was successfully used with stereolitographic technique for complete denture manufacturing. However, mechanical and biocompatibility tests need to be performed in order to extend the clinical usage.

A novel, low surface charge density, anionically modified montmorillonite for polymer nanocomposites

A new, low surface charge density, anionically modified montmorillonite (MMT) has been prepared and its polyurethane nanocomposites are prepared.

Design and Physicochemical Characterization of Novel Organic–Inorganic Hybrids from Natural Aluminosilicate Nanotubes

Surface functionalization of tubular nano-clays of imogolite and halloysite using the selective binding of organophosphonic acids and organosilane compounds, and the use of the surface modified nanotubes in polymer hybrids were studied. Surface modification of imogolite with alkyl phosphonic acid salt through the specific interaction of phosphonic acid and the exterior alumina sites of imogolite was presented. SI-ATRP was performed with the selectively adsorbed phosphonic acid functionalized ATRP-initiator to prepare polymer brushes on the imogolite surface. Selective modification of halloysite nanotube exterior and inner surfaces was demonstrated. Aqueous phosphonic acid binds to alumina sites at the tube lumen to make the lumen hydrophobic. Subsequent modification with organosilane affords bifunctionalized halloysites with both the lumen and exterior surface modified. Loading of hydrophobic organic compound to the modified lumen was confirmed. SI-ATRP was performed through the selectively adsorbed DOPA-functionalized ATRP-initiator to prepare polymer brushes on the nanotube lumen. Also, surface modified halloysite was applied for preparation of novel intelligent polyurethane nanocomposites with improved thermal stability and mechanical properties.

Angiogenic Rg1 /Sr-Doped TiO2 Nanowire/Poly(Propylene Fumarate) Bone Cement Composites

A new approach is provided for preparing radiopaque and angiogenic poly(propylene fumarate) (PPF) bone cements by integrating Sr-doped n-TiO₂ nanowires and ginsenoside Rg1 suitable for treating osteonecrosis. High aspect ratio radiopaque TiO₂ -nanowires are synthesized by strontium doping in supercritical CO₂ for the first time, showing a new phase, SrTiO₃ . PPF is synthesized using a transesterification method by reacting diethyl fumarate and propylene glycol, then functionalized using maleic anhydride to produce terminal carboxyl groups, which are subsequently linked to the nanowires. The strong interfacial adhesion between functionalized PPF and nanowires is examined by scanning electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, thermal analysis, and mechanical testing. An angiogenic modulator, ginsenoside Rg₁ , is integrated into the bone cement formulation with the mechanical properties, radiopacity, drug release, and angiogenesis behavior of the formed composites explored. The results show superior radiopacity and excellent release of ginsenoside Rg₁ in vitro, as well as a dose-dependent increase in the branching point numbers. The present study suggests this new methodology provides sufficient mechanical properties, radiopacity, and angiogenic activity to be suitable for cementation of necrotic bone.

Optimization of Injection Molding Parameters for HDPE/TiO₂ Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis

The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO₂ nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO₂), barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young’s modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L₉ orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO₂, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA) has also been applied to identify the most significant factor, and the percentage of TiO₂ nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO₂ nanocomposites fabricated through the injection molding process.

One-pot synthesis of pH-responsive hybrid nanogel particles for the intracellular delivery of small interfering RNA

This report describes a novel, one-pot synthesis of hybrid nanoparticles formed by a nanostructured inorganic silica core and an organic pH-responsive hydrogel shell. This easy-to-perform, oil-in-water emulsion process synthesizes fluorescently-doped silica nanoparticles wrapped within a tunable coating of cationic poly(2-diethylaminoethyl methacrylate) hydrogel in one step. Transmission electron microscopy and dynamic light scattering analysis demonstrated that the hydrogel-coated nanoparticles are uniformly dispersed in the aqueous phase. The formation of covalent chemical bonds between the silica and the polymer increases the stability of the organic phase around the inorganic core as demonstrated by thermogravimetric analysis. The cationic nature of the hydrogel is responsible for the pH buffering properties of the nanostructured system and was evaluated by titration experiments. Zeta-potential analysis demonstrated that the charge of the system was reversed when transitioned from acidic to basic pH and vice versa. Consequently, small interfering RNA (siRNA) can be loaded and released in an acidic pH environment thereby enabling the hybrid particles and their payload to avoid endosomal sequestration and enzymatic degradation. These nanoparticles, loaded with specific siRNA molecules directed towards the transcript of the membrane receptor CXCR4, significantly decreased the expression of this protein in a human breast cancer cell line (i.e., MDA-MB-231). Moreover, intravenous administration of siRNA-loaded nanoparticles demonstrated a preferential accumulation at the tumor site that resulted in a reduction of CXCR4 expression.

Polymeric nanobiocomposites for biomedical applications

Polymeric nanobiocomposites have recently become one of the most essential sought after materials for biomedical applications ranging from implants to the creation of gels. Their unique mechanical and biological properties provide them the ability to pass through the highly guarded defense mechanism without undergoing noticeable degradation and initiation of immune responses, which in turn makes them advantageous over the other alternatives. Aligned with the advances in tissue engineering, it is also possible to design three-dimensional extracellular matrix using these polymeric nanobiocomposites that could closely mimic the human tissues. In fact, unique polymer chemistry coupled with nanoparticles could create unique microenvironment that promotes cell growth and differentiation. In addition, the nanobiocomposites can also be devised to carry drugs efficiently to the target site without exhibiting any cytotoxicity as well as to eradicate surgical infections. In this article, an effort has been made to thoroughly review a number of different types/classes of polymeric nanocomposites currently used in biomedical fields. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1241-1259, 2017.

Solubility studies of inorganic-organic hybrid nanoparticle photoresists with different surface functional groups

The solubility behavior of Hf and Zr based hybrid nanoparticles with different surface ligands in different concentrations of photoacid generator as potential EUV photoresists was investigated in detail. The nanoparticles regardless of core or ligand chemistry have a hydrodynamic diameter of 2-3 nm and a very narrow size distribution in organic solvents. The Hansen solubility parameters for nanoparticles functionalized with IBA and 2MBA have the highest contribution from the dispersion interaction than those with tDMA and MAA, which show more polar character. The nanoparticles functionalized with unsaturated surface ligands showed more apparent solubility changes after exposure to DUV than those with saturated ones. The solubility differences after exposure are more pronounced for films containing a higher amount of photoacid generator. The work reported here provides material selection criteria and processing strategies for the design of high performance EUV photoresists.

Optoelectrical, morphological and mechanical features of nitrophenyl supported poly(1,3,4-oxadiazole)s and their nanocomposites with TiO2

Charge transfer phenomenon and redox behaviour, of PPNO/PNPPO nanocomposites, triggered by TiO₂ nanoparticles.

Synthesis of Water-Based Dispersions of Polymer/TiO₂ Hybrid Nanospheres

We develop a strategy for preparing water-based dispersions of polymer/TiO₂ nanospheres that can be used to form composite materials applicable in various fields. The formed hybrid nanospheres are monodisperse and possess a hierarchical structure. It starts with the primary TiO₂ nanoparticles of about 5 nm, which first assemble to nanoclusters of about 30 nm and then are integrated into monomer droplets. After emulsion polymerization, one obtains the water-based dispersions of polymer/TiO₂ nanospheres. To achieve universal size, it is necessary to have treatments with intense turbulent shear generated in a microchannel device at different stages. In addition, a procedure combining synergistic actions of steric and anionic surfactants has been designed to warrant the colloidal stability of the process. Since the formed polymer/TiO₂ nanospheres are stable aqueous dispersions, they can be easily mixed with TiO₂-free polymeric nanoparticle dispersions to form new dispersions, where TiO₂-containing nanospheres are homogeneously distributed in the dispersions at the nanoscale, thus leading to various applications. As an example, the proposed strategy has been applied to generate polystyrene/TiO₂ nanospheres of about 100 nm in diameter.

Nanomaterials: the next step in injectable bone cements

Injectable bone cements (IBCs) are biocompatible materials that can be used as bone defect fillers in maxillofacial surgeries and in orthopedic fracture treatment in order to augment weakened bone due to osteoporosis. Current clinically available IBCs, such as polymethylmethacrylate and calcium phosphate cement, have certain advantages; however, they possess several drawbacks that prevent them from gaining universal acceptance. New gel-based injectable materials have also been developed, but these are too mechanically weak for load-bearing applications. Recent research has focused on improving various injectable materials using nanomaterials in order to render them suitable for bone tissue regeneration. This article outlines the requirements of IBCs, the advantages and limitations of currently available IBCs and the state-of-the-art developments that have demonstrated the effects of nanomaterials within injectable systems.