A novel acrylate-PDMS composite latex with controlled phase compatibility prepared by emulsion polymerization

In this paper, a series of acrylate-polydimethylsiloxane (PDMS) composite latexes was prepared and studied systematically to find the factors that affect their performances. At first, the modified PDMS was synthesized to react with acrylate monomers and participate in free radical polymerization. Then, the modified PDMS was blended with acrylate monomers, and the acrylate-PDMS composite latexes with different formulas were obtained by emulsion polymerization. Because the blending monomers were constrained in the micelle, the two components were interconnected with each other by a covalent bond and the phase compatibility between the two components could be controlled well. Chemical constitution and the morphology of acrylate-PDMS composite latexes were confirmed by using FTIR spectroscopy, TEM, and SEM measurements, respectively. Thermophysics and heat resistance of the dried coatings based on acrylate-PDMS composite latexes were studied using DSC and TGA tests, respectively. Anticorrosion properties of the cured coatings based on acrylate-PDMS composite latexes were confirmed by potentiodynamic polarization test. With low surface tension, good toughness, excellent weather-proof properties, and good high and low temperature stability, the modified PDMS component can improve the performance of the traditional acrylate latex-based waterborne resin effectively, and the prepared acrylate-PDMS composite latexes can be used in heavy-duty anticorrosion applications.     

Novel gamma irradiated agarose-gelatin-hydroxyapatite nanocomposite scaffolds for skin tissue regeneration

Agarose-gelatin-hydroxyapatite composites prepared by freeze-drying technique were gamma irradiated with various doses (25 kGy, 50 kGy and 100 kGy). X-ray Diffraction (XRD) analysis revealed the pure phase of HAp and the intensity of prominent planes of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAp) were found to decrease on irradiation. Fourier Transform Infrared spectra (FTIR) showed functional groups of HAp and polymer composites, and higher disorder of the polymer matrix on irradiation. In addition, gamma irradiation led to a drastic reduction in the wettability (62%) and the compressive modulus (76%) of the scaffolds. There was significant enhancement (113%) in pore size of the scaffolds at higher fluence (100 kGy). The swelling and the dissolution studies of the gamma irradiated scaffolds showed that it had an appreciable change in the scaffold's mechanical and biological properties viz., compressive modulus, cell proliferation, hemolysis etc. The irradiated biomaterials exhibited enhanced hemocompatibility, antimicrobial activity and cell viability. The above results clearly reveal that the gamma irradiation is a suitable tool to tailor the multifunctional properties of the composites and could be used for various biomedical applications.     

Influence of ethanol on the HAp coatings prepared by hydrothermal electrodeposition on C/C composites

Hydroxyapatite (HAp) coatings were prepared on carbon/carbon (C/C) composites with a novel hydrothermal electrodeposition method. The as-prepared HAp coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, and scanning electron microscope (SEM) analyses. The influence of ethanol on the phases and microstructures of HAp coatings was investigated. Results show that the coatings’ crystallization shows little change with the increase in ethanol content up to 15%, but the density, homogeneousness, and adhesion with the substrate of HAp coatings obviously improved. The deposition mechanism of the HAp coating is also discussed. Thus, it is helpful to get dense and good-adhesion HAp coatings when ethanol is added into the solution during the hydrothermal electrodeposition process.     

Fabrication of Hydroxyapatite with Bioglass Nanocomposite for Human Wharton’s-Jelly-Derived Mesenchymal Stem Cell Growing Substrate

Recently, composite scaffolding has found many applications in hard tissue engineering due to a number of desirable features. In this present study, hydroxyapatite/bioglass (HAp/BG) nanocomposite scaffolds were prepared in different ratios using a hydrothermal approach. The aim of this research was to evaluate the adhesion, growth, viability, and osteoblast differentiation behavior of human Wharton’s-jelly-derived mesenchymal stem cells (hWJMSCs) on HAp/BG in vitro as a scaffold for application in bone tissue engineering. Particle size and morphology were investigated by TEM and bioactivity was assessed and proven using SEM analysis with hWJMSCs in contact with the HAp/BG nanocomposite. Viability was evaluated using PrestoBlue^TM assay and early osteoblast differentiation and mineralization behaviors were investigated by ALP activity and EDX analysis simultaneously. TEM results showed that the prepared HAp/BG nanocomposite had dimensions of less than 40 nm. The morphology of hWJMSCs showed a fibroblast-like shape, with a clear filopodia structure. The viability of hWJMSCs was highest for the HAp/BG nanocomposite with a 70:30 ratio of HAp to BG (HAp70/BG30). The in vitro biological results confirmed that HAp/BG composite was not cytotoxic. It was also observed that the biological performance of HAp70/BG30 was higher than HAp scaffold alone. In summary, HAp/BG scaffold combined with mesenchymal stem cells showed significant potential for bone repair applications in tissue engineering.     

Structural and biological properties of novel Vanadium and Strontium co-doped HAp for tissue engineering applications

The development of novel bioactive materials with improved physical and biological properties is crucial for advancing tissue engineering applications. In this study, we synthesized a Vanadium and Strontium co-doped hydroxyapatite (V–Sr:HAp) nanoparticle intending to enhance the performance of pure HAp. The V–Sr:HAp nanoparticles were synthesized using a microwave-assisted reflux condensation method, and their structural and chemical characteristics were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The morphology and elemental composition of the nanoparticles were examined through scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The XRD analysis confirmed the presence of characteristic peaks of HAp in each sample. SEM images revealed well-connected and highly agglomerated small sphere-like morphology in both pure HAp and V–Sr:HAp nanoparticles. The Vickers hardness test demonstrated the improved mechanical strength in V–Sr:HAp compared to pure HAp. Antibacterial efficacy was evaluated using an agar diffusion test, which showed enhanced antibacterial activity in the co-doped HAp samples against S. aureus and P. aeruginosa. Moreover, the Ca–P deposition rate on the surface of the co-doped HAp samples during biomineralization was higher. Hemolysis assay results have indicated compatibility of both pure HAp and V–Sr:HAp with human blood (<5% lysis). The results of cell viability tests demonstrate that the V and Sr co-doped HAp samples do not exhibit any cytotoxic effects and instead promote cell proliferation. Overall, the incorporation of V and Sr metal ions into HAp presents a promising bio-functional tool for tissue engineering applications, offering improved mechanical and antibacterial properties.     

Corrosion protection of AISI 316 stainless steel by ALD alumina/titania nanometric coatings

Stainless steels are used today in a wide range of applications as a result of their combination of high corrosion resistance and good mechanical properties. In some applications, for example, temporary contact biomedical devices or solar water heaters, corrosion resistance may need further improvement, and surface coatings may be applied for enhanced protection. In this study, AISI 316 stainless steel samples with two different standard industrial finishes were coated using atomic layer deposition (ALD) of Al₂O₃/TiO₂ layers. The morphology, composition and corrosion protection was then investigated using different techniques. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to obtain a morphological characterization of coatings and substrates. Glow discharge optical emission spectrometry (GDOES) was used to obtain an in-depth profile of composition. Polarization curves in a 0.2 M NaCl solution were used to evaluate the corrosion protection given by the coatings. The deposited ALD layers were found to be almost flawless. The measured RMS roughness values were compared before and after the ALD, and were around 50 and 370 nm for the two samples. GDOES profiles were strongly influenced by the roughness of the substrate. The corrosion protection obtained on AISI 316 stainless steel by the application of nanometric coatings proved to be very effective in reducing the passive region current density from 10^?7 to less than 10^?9 A/cm² and increasing the passive region potential interval from 0.8 to 1.3 V before breakdown.     

Effect of irradiation on mechanical and structural properties of ethylene vinyl acetate copolymers hollow fibers

Effect of irradiation on mechanical and structural properties of ethylene vinyl acetate copolymers (EVA) hollow fibers was studied by the tests such as determination of gel content, density, tensile, FTIR, SEM, and DMA. These effects were discussed based on dose and irradiation environment. The results of gel content depicted that irradiated EVA in ambient conditions had tendency to chain scission while the crosslinking overcame in irradiated samples under nitrogen. Density insignificantly enhanced with irradiation dose. In tensile test, irradiation induced increase in tensile strength and decrease in elongation at break (especially in samples irradiated in nitrogen). Also, changing in layer orientation could be observed by SEM images. In addition, irradiation caused altering peak intensity in FTIR spectrum. DMA results demonstrated that irradiation broaden the elastic zone. Totally, irradiation enhances features especially in irradiated EVA18 in nitrogen. Since, according to stabilization of induced deformation and improvement of mechanical properties (that created by radiation), the irradiated samples can be used in different applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Composition,structure and mechanical properties of the titanium surface after induction heat treatment followed by modification with hydroxyapatite nanoparticles

Coatings of titania (TiO₂) and "titania–hydroxyapatite" were prepared by oxidation of commercially pure titanium VT1-00 using induction heat treatment (IHT), followed by modification with colloidal hydroxyapatite (HAp) nanoparticles. The IHT treatment was performed at temperatures within 600–1200 °C for 300 s. According to the results of scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray fluorescent analysis (EDX), nanoindentation and in vitro testing, titania coatings of high morphological heterogeneity, and high mechanical properties and biocompatibility were formed on the titanium surface after IHT. The coatings were found to consist of nano- and submicron crystals of oval, needle-like, plate and prismatic shapes. A subsequent modification with HAp nanoparticles of the coated titanium substrate leads to accelerated formation of mechanically strong oxidebioceramic composite coatings. It was established that the porous oxide coatings modified with nanoparticles of HAp that were formed at temperatures from 800 to 1000 °C and holding for at least 30 s had a high biocompatibility.     

Morphological,mechanical, and biological evolution of pure hydroxyapatite and its composites with titanium carbide for biomedical applications

Pure hydroxyapatite (HAp) was synthesized successfully via a wet chemical precipitation method. To study the influence of TiC (weight % of 5, 10, 15) substitution on the mechanical behavior of pure HAp, its composites with TiC were synthesized using a solid-state reaction method. Herein, detailed investigations of pure HAp and its composites using X-ray powder diffraction (XRD), FTIR spectroscopy, Raman spectroscopy, UV-VIS spectroscopy, SEM followed by EDAX and particle size analysis were carried out. XRD study reveals the phase stability of the prepared HAp and composite samples. However, FTIR and Raman spectroscopic studies revealed the bond formation among the various constituents. Mechanical behavior of HAp, and its composites with TiC were studied using numerous parameters like density, Young's modulus, fracture toughness, and load absorption capability. Based on these studies, it was revealed that the addition of 5 wt % substitution of TiC sintered at 1200 °C significantly enhanced the mechanical properties of pure HAp. Hence, 5 wt % of TiC composite 95HAp-5TiC showed the best mechanical characteristics such as density (2.3060 g/cm³), Young's modulus (14.53 MPa), fracture toughness (19.82 MPa m^1/2), maximum compressive strength (186 MPa) respectively. Cytotoxicity and osteogenic activities of the synthesized pure HAp and its composite, 95HAp-5TiC were performed using osteoblast cells (mouse calvarial) at different concentrations of the samples (0.01 μg, - 100 μg). From the above studies, the cell viability and ALP activities of the composite, 95HAp-5TiC found to be excellent than that of pure HAp. Hence, this composite sample may be utilized for bone implant applications.     

Effect of conducting composite carbon nanotube‐poly(o‐toluidine) coatings on the corrosion resistance of stainless steel material

This study examines the use of poly(o‐toluidine) (POT) coatings and poly(o‐toluidine)/oxidized multi‐walled carbon nanotubes (POT‐MWCNT) composite on 304 stainless steel for corrosion protection. The POT coatings and its composite were synthesized on steel substrates under cyclic voltammetric conditions. These coatings were characterized by cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The ability of POT and its composite to serve as a corrosion protective coating was examined by potentiodynamic polarization, CV, and potential‐time measurements. The nanocomposite layers as well as the pure POT layer keeps the stainless steel in a passive state. POLYM. COMPOS., 34:1180–1185, 2013. © 2013 Society of Plastics Engineers     

Synthesis and characterization of calcium phosphate coatings on Nitinol

In recent years, coating of metal orthopedic implants with bioactive layers to promote fixation with bones has become increasingly common. Calcium phosphate coatings on the Nitinol surface were formed using two low-temperature methods: sol–gel and electrochemically assisted deposition. The coatings formed were characterized using: X-ray diffraction analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. Cyclic voltammetry studies were carried out in the deposition solution to determine parameters for electrodeposition and to understand electrochemistry of deposition. The barrier properties and corrosion resistance of coatings were tested in the physiological Hanks’ solution using electrochemical impedance spectroscopy. The sol–gel deposited coating consisted of two phases, hydroxyapatite and tricalcium phosphate (TCP). Apatite coatings containing TCP offered the opportunity to create a grafting material with high bioactivity and bioresorbility. The electrodeposited coating consisted of Ca-deficient HAp which resembles to biological HAp.     

硅橡胶膜用于植物油/己烷胶团中溶剂回收的研究

Traditional solvent recovery in the extraction step of edible oil processing is distillation, which consumes large amounts of energy. If the distillation is replaced by membrane process, the energy consumption can be reduced greatly. In this work, two kinds of membrane, PDMS (polydimethylsiloxane) composite membrane and Zeolite filled PDMS membrane were prepared, in which asymmetric microporous PVDF (polyvinylidenefluoride) membrane prepared with phase inversion method was functioned as the microporous supporting layer in the flat-plate composite membrane. The different function compositions of the PDMS/PVDF com-posite membranes were characterized by reflection Fourier transform infrared (FTIR) spectroscopy. The surface and section of PDMS/PVDF composite membranes were investigated by scanning electron microscope (SEM). The PDMS NF (nanofiltration) membranes were then applied in the recovery of hexane from soybean oil/hexane miscellas (1︰3, mass ratio). The effects of pres-sure (0.5-1.5 MPa), cross-linking temperature and PDMS layer thickness on membrane performances were investigated. The results indicated that both two kinds of NF membranes were promising for solvent recovery, and zeolite filled in PDMS NF membrane could enhance the separation performance.     

Calcium phosphates of biological importance based coatings deposited on Ti-15Mo alloy modified by laser beam irradiation for dental and orthopedic applications

Ti-15Mo alloy samples were irradiated by pulsed Yb:YAG pulsed laser beam under air and atmospheric pressure. Sequentially, calcium phosphate coatings were deposited on the irradiated surfaces by the biomimetic method. The formation of calcium phosphates (CaP) under biological medium and SBF (Synthetic/Simulated Body Fluid) occurs in the presence of Ca²⁺ and PO₄^3- ions, as well as ions such as: Mg^2+, HCO₃^-, K⁺ and Na⁺, which facilitates the mimicking of the biological process. The biomimetic calcium phosphates-based surfaces were submitted to heat treatment conditions at 350?°C and 600?°C. The present study correlates four conditions of fluency (1.91, 3.17, 4.16 and 5.54?J/cm², respectively) as established have a sufficient energy to promote ablation on the laser beam irradiated surfaces. Likewise, it has been demonstrated the processes of fusion and fast solidification from the laser beam irradiation, under ambient atmosphere, inducing the formation of stoichiometric (TiO₂₎ and non-stoichiometric titanium oxides (TiO, Ti₃O, Ti₃O₅ and Ti₆O) with different oxide percentages depending on the fluency applied. Besides that, laser modification has allowed a clean and reproducible process, providing no traces of contamination, an important feature for clinical applications. The morphological and physico-chemical analysis indicated the formation of a multiphase coatings depending on the heat treatment temperature performed to 350?°C (ACP1–2, CDHA, HA phases) and 600?°C (CDHA, HA and β-TCP phases). It is worth noting multiphasic bioceramic systems has been gaining attention for biomedical applications. The laser beam irradiation associated to bioactive coatings of calcium phosphates of biological interest have shown to be promising and economically feasible for use in clinical applications.     

Bioactive Sol‐Gel Coatings

Recent sol‐gel techniques enable bioactive composite layers to be prepared by the embedding of bioactive compounds, biomolecules (BMs) and cellular systems within inorganic layers. These novel bioactive layers offer interesting new applications, e.g. biocompatible coatings on implants and medical products, the preparation of biosensors and biocatalysts, and coatings that can release biocides in a controlled manner.     

In vitro blood compatibility of modified PDMS surfaces as superhydrophobic and superhydrophilic materials

The surface of polydimethylsiloxane rubber (PDMS) was irradiated by a CO₂‐pulsed laser. The irradiated surfaces were grafted by hydroxyethylmethacrylate phosphatidylcholine (HEMAPC) by using the preirradiation method. The laser‐treated surfaces and HEMAPC‐grafted PDMS surfaces were characterized by using a variety of techniques including ATR‐FTIR spectroscopy, scanning electron microscopy (SEM), and wettability, which was measured by a water‐drop contact angle. Different surfaces with different wettability were prepared. These surfaces, including untreated PDMS (hydrophobic), laser‐treated PDMS (superhydrophobic), and HEMAPC‐grafted surfaces (superhydrophilic), were used for a platelet adhesion study. Results from in vitro testing indicated that chemical structures, such as negative‐charge polar groups and wettability, are important factors in blood compatibility of these surfaces and the superhydrophilic (the most wettable) and the superhydrophobic (the most unwettable) of modified PDMS surfaces have excellent blood compatibility compared to the unmodified PDMS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:2042–2047, 2004     

EIS study on failure process of two polyurethane composite coatings

The performance of acrylic polyurethane composite coating and aliphatic urethane composite coating in 3.5% NaCl solution under ultra-violet radiation was studied with methods of EIS, SEM and FTIR. For aliphatic polyurethane coating, the coating resistance decreased and the coating capacitance and porosity increased more quickly than acrylic polyurethane coating. The acrylic polyurethane composite coatings showed better performance than aliphatic polyurethane composite coatings. IR spectra showed that under UV irradiation conditions, the failure mechanism of the two polyurethane coatings was the transformation of sec-amide to primary amides. The fractured bonds in acrylic polyurethane were mainly C–O bonds, while in aliphatic polyurethane they were mainly C–N bonds. The lower protection property of aliphatic polyurethane coating may be mainly attributed to the C–N bonds which are more liable to be broken.     

Effect of Morphological Characteristics and Biomineralization of 3D-Printed Gelatin/Hyaluronic Acid/Hydroxyapatite Composite Scaffolds on Bone Tissue Regeneration

The use of porous three-dimensional (3D) composite scaffolds has attracted great attention in bone tissue engineering applications because they closely simulate the major features of the natural extracellular matrix (ECM) of bone. This study aimed to prepare biomimetic composite scaffolds via a simple 3D printing of gelatin/hyaluronic acid (HA)/hydroxyapatite (HAp) and subsequent biomineralization for improved bone tissue regeneration. The resulting scaffolds exhibited uniform structure and homogeneous pore distribution. In addition, the microstructures of the composite scaffolds showed an ECM-mimetic structure with a wrinkled internal surface and a porous hierarchical architecture. The results of bioactivity assays proved that the morphological characteristics and biomineralization of the composite scaffolds influenced cell proliferation and osteogenic differentiation. In particular, the biomineralized gelatin/HA/HAp composite scaffolds with double-layer staggered orthogonal (GEHA20-ZZS) and double-layer alternative structure (GEHA20-45S) showed higher bioactivity than other scaffolds. According to these results, biomineralization has a great influence on the biological activity of cells. Hence, the biomineralized composite scaffolds can be used as new bone scaffolds in bone regeneration.     

Halloysite nanotube reinforced polylactic acid composite

Polylactic acid (PLA) has a long history in medical applications. Reinforced PLA has the potential to be used in the medical applications that require high mechanical strength such as coronary stents and bone fixation devices. Halloysite nanotube (HNT) has received considerable attention recently due to its tubular structure, high aspect ratio, high mechanical strength, thermal stability, biocompatibility and sustained drug releasing properties. Halloysite has been investigated in compounding with many polymers. However, the research in compounding halloysite with biodegradable materials for use in biological applications is sparse. In this study various weight fractions of HNT was compounded with the biodegradable polymer PLA using a melt compounding method. Tensile test, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), contact angle test, scanning electron microscopy (SEM), void content and thermogravimetric analysis (TGA) were carried out to study the PLA/HNT composite. Tensile test results indicated that Young's modulus and stiffness of PLA were enhanced with the addition of HNT; FTIR spectra showed the interaction between the PLA and HNT; whereas contact angle measurements indicated that the wettability of the PLA/HNT composite was not affected by the addition of HNT. However, the thermal stability of PLA was adversely effected by the addition of HNT which may be related to the presence of voids between the polymer and matrix. Nevertheless, the reinforced PLA/HNT composite, which maintains the surface characteristics, may prove beneficial for use in biological applications. POLYM. COMPOS., 38:2166–2173, 2017. © 2015 Society of Plastics Engineers     

Study on preparation and anticorrosive performance of a new high hydrophobic anticorrosive coating

Water-based anticorrosive coatings have poor water resistance, which easily lead to coating deterioration and metal corrosion. In order to improve the anticorrosion performance of waterborne coating, herein, the polytetrafluoroethylene/dimethyl siloxane/epoxy resin (PTFE/PDMS/EP) hydrophobic anticorrosive coating was prepared by layer-by-layer construction. The spatial structure and microscopic morphology of the hydrophobic coating were analyzed by XRD, FTIR, and SEM. The hydrophobicity and corrosion resistance of the composite coating were analyzed by hydrophobicity test, electrochemical polarization curve, hydrophobicity and corrosion resistance test of the mixed layer, Tafel polarization curves, and AC impedance spectrum. The results showed that the water contact angle of PTFE/PDMS/EP coating reached 141° and the protection efficiency of PTFE/PDMS/EP coating was 98.62%. After soaking for 7 days, the corrosion process still stays at the initial stage, which was mainly due to the good sealing and barrier properties and high anticorrosion efficiency of PTFE/PDMS/EP coating. The coating has high corrosion protection efficiency and long service life, which is of great significance to metal corrosion protection in harsh marine environments.     

PTFE对PDMS复合膜在低浓度有机物水溶液中渗透汽化性能的影响

制备了聚四氟乙烯（PTFE）超细粉体填充聚二甲基硅氧烷（PDMS）复合膜,通过扫描电子显微镜、傅里叶变换红外光谱仪、热失重分析仪等测试仪器对复合膜进行了表征,利用低浓度有机物（乙醇、丙酮、正丙醇）水溶液体系进行渗透汽化,并由单组分溶解实验计算了有机物（乙醇、丙酮、正丙醇）在复合膜中的溶解度。结果表明,PTFE含量由0增加至10 %（质量分数,下同）时, 复合膜的表面积及热稳定性得到了提高,有机物乙醇、丙酮、正丙醇在复合膜中的溶解度分别由0.0923、0.1589和0.2691 g/g提高至0.0991、0.1678和0.2773 g/g;加入PTFE后提高了复合膜的渗透汽化性能。