Influence of Incorporation of Gallium Oxide Nanoparticles on the Structural and Optical Properties of Polyvinyl Alcohol Polymer

In the present work, gallium oxide nanoparticles (nGa₂O₃) are synthesized via the thermal microwave combustion method, while nanocomposites of polyvinyl alcohol (PVA) polymer with various concentrations (0, 1, 2, 3, 4, and 5 wt%) of nGa₂O₃ are prepared by the casting technique. The structural characterization of nGa₂O₃, PVA, and films of PVA-Ga₂O₃ nanocomposites are studied using X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), and Fourier-transform infrared (FTIR) spectroscopy. The HRTEM and XRD examinations showed that the prepared nGa₂O₃ has an average crystallite size of?~?5.6 nm and particle size of?~?0.9 µm. The FTIR analysis reveals the occurrence of some interactions between nGa₂O₃ and the functional groups of the PVA structure. On another side, the refractive index, absorption coefficient, and optical bandgap (E_g) were determined using the Wemple-DiDomenico single oscillator model. It was shown that E_g slightly reduced from 3.61 to 3.55 eV with increasing the Ga₂O₃ content to 3 wt%, while raised again up to 3.58 eV for 5 wt% Ga₂O₃. Other optical characteristics such as the optical density, extinction coefficient, optical susceptibility, thermal emissivity, optical sheet resistance for the PVA?Ga₂O₃ nanocomposites are investigated. The linear and nonlinear optical parameters together with their dependencies on the doping ratio reveals the qualification of PVA?Ga₂O₃ nanocomposites for nonlinear optical applications.

     

氧化石墨烯改性聚乙烯醇纤维的制备及性能研究

采用凝胶纺丝制备了氧化石墨烯(GO)改性的高强聚乙烯醇(PVA)纤维,研究了GO的含量、纺丝工艺对GO-PVA纤维性能的影响。通过红外光谱、热失重和热失重速率、差示扫描分析、X射线衍射等方法对GO-PVA纤维的结构与性能进行了研究。结果表明:GO-PVA纤维具有更好的拉伸性能,当GO质量分数在0.1%的时候,GO-PVA纤维具有最好的拉伸性能,其最大拉伸倍数、强度和模量分别为41倍、15.6 c N/dtex和185 c N/dtex,比纯PVA纤维提高了36.7%、16.4%和79.6%。     

Influence of K2CrO4 Doping on the Structural,Optical and Dielectric Properties of Polyvinyl Alcohol/K2CrO4 Composite Films

Polyvinyl alcohol/potassium chromate (K₂CrO₄) composite films were prepared by solution casting technique using distilled water as a solvent, and were further investigated using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction, thermogravimetric analysis, optical microscopy, scanning electron microscopy, and dielectric measurements. Microscopic studies reveal that K₂CrO₄ was homogenously mixed with polyvinyl alcohol matrix due to interfacial interaction between polyvinyl alcohol and K₂CrO₄. The composite films showed very high dielectric constant and relatively low dielectric loss. Hence, such composite materials with improved dielectric properties could be useful for fabrication of electrical charge storage device.     

Functional Properties of Gelatin/Polyvinyl Alcohol Films Containing Black Cumin Cake Extract and Zinc Oxide Nanoparticles Produced via Casting Technique

This study aimed to develop and characterize gelatin/polyvinyl alcohol (G/PVA) films loaded with black cumin cake extract (BCCE) and zinc oxide nanoparticles (ZnONPs). The BCCE was also applied for the green synthesis of ZnONPs with an average size of less than 100 nm. The active films were produced by a solvent-casting technique, and their physicochemical and antibacterial properties were investigated. Supplementation of G/PVA film in ZnONPs decreased the tensile strength (TS) from 2.97 MPa to 1.69 MPa. The addition of BCCE and ZnONPs increased the elongation at the break (EAB) of the enriched film by about 3%. The G/PVA/BCCE/ZnONPs film revealed the lowest water vapor permeability (WVP = 1.14 × 10⁻⁹ g·mm·Pa⁻¹·h⁻¹·mm⁻²) and the highest opacity (3.41 mm⁻¹). The QUick, Easy, New, CHEap and Reproducible (QUENCHER) methodologies using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) and cupric ion reducing antioxidant capacity (CUPRAC) were applied to measure antioxidant capacity (AC) of the prepared films. The incorporation of BCCE and ZnONPs into G/PVA films enhanced the AC by 8–144%. The films containing ZnONPs and a mixture of BCCE and ZnONPs inhibited the growth of three Gram-positive bacterial strains. These nanocomposite films with desired functional properties can be recommended to inhibit microbial spoilage and oxidative rancidity of packaged food.     

Preparation and Properties of Biodegradable Polymer Film Based on Polyvinyl Alcohol and Tropical Fruit Waste Flour

In this study, two different types of tropical fruit waste flour, rambutan waste flour (RWF) and banana waste flour (BWF), were blended with polyvinyl alcohol (PVOH) by solution casting method. The structure of the blend film was characterised by Fourier Transform Infrared Spectroscopy. The tensile strength and elongation at break of tropical fruit waste flour-filled polyvinyl alcohol were lower, but the tensile modulus was higher, than that of PVOH film. At a similar blend ratio, the tensile properties of the PVOH/RWF film were higher than the PVOH/BWF film, but the PVOH/BWF film showed higher water uptake than PVOH/RWF film.     

Enhancing Photophysical Properties of MDMO-PPV-DMP Conjugated Polymer via Incorporation Anatase Titania Nanoparticles

Improving photophysical properties of poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene]-end capped with dimethylphenyl, MDMO-PPV-DMP, was achieved via incorporation anatase titania nanoparticles (TiO₂ NPs). Various contents of TiO₂ NPs (up to 50 wt%) were dispersed into fixed concentration of the MDMO-PPV-DMP (5 mg/mL) via solution blending method followed by spin coating onto cleaned glass substrates to form their thin films. The formation of MDMO-PPV-DMP/TiO₂ nanocomposites was evidenced from the results of X-ray diffractograms and Fourier transform infrared spectra, while the homogeneity of the films was detected by field emission-scanning electron microscopy (FE-SEM). Increasing the contents of TiO₂ NPs resulted in a slight decrease (up to ~?0.07 eV) in both direct and indirect energy band gaps of the MDMO-PPV-DMP in the nanocomposite thin films. A higher degree of disorder in the electronic structure of the MDMO-PPV-DMP/TiO₂ nanocomposite and increasing the localized states density within the forbidden gap can be achieved by increasing the energy tail values and decreasing the steepness parameter with rising the TiO₂ NPs content. The enhancement in emission intensity and broadening of emission spectra with increasing the TiO₂ NPs content can be explained by the charge trapping effect and particle size distribution, respectively. Moreover, the incorporation of TiO₂ NPs into the MDMO-PPV-DMP led to tuning its emitted light color which is of distinct interest in optoelectronic devices.

     

磷酸化聚乙烯醇修饰磁性纳米粒子对铀酰的吸附性能研究

在Fe3O4磁性纳米粒子表面复盖一层磷酸化聚乙烯醇制备了一种用于从水相选择性分离铀酰的复合型磁性纳米粒子。用平衡吸附法研究了纳米粒子对铀酰的吸附性能和选择识别能力,且探讨了实验条件对纳米粒子吸附性能的影响。结果表明在竞争金属离子存在下,纳米粒子对铀酰具有较高的吸附能力和选择识别能力,且可以循环使用。     

生物矿化法制备氧化镓颗粒及其性能表征

以蚕丝蛋白为模板,在相对温和的条件下通过生物矿化的手段形成具有特殊形貌的α-GaOOH颗粒,并通过在不同温度下煅烧α-GaOOH得到α-Ga2O3和β-Ga2O3.采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)和荧光分光光度计(PL)等手段研究了丝素蛋白多肽和矿化时间对颗粒的影响,对其生物矿化机理进行了初步探讨.结果表明,所制备的β-Ga2O3具有优良的发光特性,丝素蛋白多肽模板以无定形的结构与产物结合在一起,并且经过高温烧结后仍以碳膜的形式包覆在材料的表面.这种碳膜结构对于提高材料的生物学性能起着重要的作用.     

Structural Characterization and Optical Properties of Perovskite ZnZrO3 Nanoparticles

Perovskite ZnZrO₃ nanoparticles were synthesized by hydrothermal method, and their microstructures and optical properties were characterized. The crystallinity, phase formation, morphology and composition of the as‐synthesized nanoparticles were characterized by X‐ray diffraction (XRD), selected area electron diffraction (SAED), high‐resolutiontransmission electron microscopy (HRTEM), and energy‐dispersive X‐ray (EDX) spectroscopy analysis, respectively. TEM images demonstrated that the average particle size of the ZnZrO₃ powders was increased with increasing the Zn/Zr molar ratios in the precursors, and more large ZnZrO₃ particles with cubic morphology were observed at high Zn/Zr molar ratios. In addition, the phase structures of the ZnZrO₃ particles were also evolved from a cubic to tetragonal perovskite phase, as revealed by XRD and SAED patterns. HRTEM images demonstrate that surface structures of the ZnZrO₃ powders synthesized at high Zn/Zr molar ratios, are composed of corners bound by the {100} mini‐facets, and the surface steps lying on the {100} planes are frequently observed, whereas the (101) facet isoccasionally observed. The formation of such a rough surface structure is understood from the periodic bond chain theory. Quantitative EDX analyses demonstrated that the atomic concentrations (at.%) of Zn:Zr:O in the particles were 20.70:21.07:58.23, as close to the composition of ZnZrO₃. In the optical spectra, a significant red shift of the absorption edges (for the ZnZrO₃ nanopowders) from UV to visible region (from 394 to 417 nm) was observed as increasing the Zn/Zr molar ratios in the precursors, which corresponds to that the band gap energies of the ZnZrO₃ nanopowders can be continuously tuned from 3.15 to 2.97 eV. This opens an easy way to tune the band gap energies of the ZnZrO₃ nanopowders.     

Studying the Effect of Cobalt Doping on Optical and Magnetic Properties of Zinc Oxide Nanoparticles

Silicon - Nano-crystalline powders of Zn1−xCoxO with $left (0.0le xle 0.07 right )$ have been synthesized by sol-gel method. X-ray diffraction patterns of the prepared samples confirm the...     

聚乙烯醇改性水溶性高分子染料制备工艺研究

本课题以聚乙烯醇与活性蓝KN-R为原料合成大分子染料,并用硫酸钠和硼砂对其进行凝胶沉淀.用乙醛与大分子染料进行缩醛反应,以降低大分子染料的水溶性.通过考察大分子染料涂料染色织物的摩擦牢度、皂洗牢度来选择大分子染料的合成条件.通过单因子实验和正交实验确定了合成大分子染料的优化工艺:温度为 75℃,时间为2.5小时,pH值...     

聚乙烯醇脱氢酶的分离纯化及其酶学性质

采用(NH4)2SO4分级沉淀及Q-Sepharose HP柱层析两步纯化,首次从可高效降解聚乙烯醇(PVA)的混合菌系发酵产物中分离纯化获得了纯蛋白聚乙烯醇脱氢酶(PVADH),并对其酶学性质进行了研究. 结果表明,PVADH分子量为134.3 kDa,最适作用温度为35℃,最适作用pH值为7.5;PVADH以仲醇为底物时酶活性普遍高于以其他醇类为底物时,PVADH与PVA反应产物中检测到羰基化合物,证实PVADH对PVA有降解作用.     

Polyvinyl Alcohol Film Materials Containing Biopolymers: Preparation and Properties

The properties and conditions of fabrication of spinning solutions based on polyvinyl alcohol containing the enzyme protease C, a high-molecular-weight antimicrobial, polyhexamethyleneguanidine hydrochloride, and modifying additives of different kinds — the polysaccharide sodium alginate and sodium tetraborate, were investigated. A correlation was established between the proteolytic activity of the film materials, degree of swelling, and composition of the spinning solutions used to prepare them.     

改性剂PVA对Lyocen纤维结构和性能的影响

将聚乙烯醇（PVA）加入到纤维素／NMMO-H20溶液中进行纺丝,制备了不同PVA含量的Lyocell纤维,并对纤维的结构和性能进行了表征。结果表明,添加适量的PVA可以降低纺丝原液的黏度,提高纺丝液的可纺性,明显提高Lyocell纤维的强度和模量;通过x射线衍射测试,发现添加PVA之后Lyocell纤维仍然具有纤维素II晶型的结构;此外,PVA的加入还可以改善Lyocell纤维的抗原纤化性能,提高Lyocell纤维的热稳定性。     

Effect of Cobalt and Nickel Doping on Structural and Magnetic Properties of Iron Oxide Nanoparticles

Two series samples of Iron Oxide nanoparticles doped with nickel and cobalt with different doping values (x?=?0.01; 0.03; 0.05 and 0.07), were successfully synthesized by using sol–gel method, and then they were characterized by X-ray diffraction, scanning electron and vibrating sample magnetometer (VSM). X-ray diffraction analysis of two series samples showed the formation α-Fe₂O₃ nanoparticles, accompanied by two phases iron spinels, CoFe₂O₄ and NiFe₂O₄. In addition, the variations in grain size were observed for both two series. The observation by scanning electron microscopy reveals a change in the morphology of the grains of all the samples doped, which confirm the cobalt and nickel effect on the morphology of iron oxide nanoparticles. Magnetic measurements which were measured by VSM showed significant magnetic parameters such as coercivity and magnetization besides the ferromagnetic behavior of both two series doped with Cobalt and Nickel.

     

Eco-Friendly Synthesis of Graphene Oxide Reinforced Hydroxypropyl Methylcellulose/Polyvinyl Alcohol Blend Nanocomposites Filled with Zinc Oxide Nanoparticles for High-k Capacitor Applications

Polymer/inorganic nanocomposites comprising of hydroxypropyl methylcellulose and polyvinyl alcohol as a polymer matrix and unique combination of graphene oxide and zinc oxide nanoparticles as fillers have been prepared using colloidal processing technique and characterized using various analytical methods. The dielectric properties of the nanocomposites are investigated using impedance analyzer. The nanocomposites show improvement in the dielectric properties compared to hydroxypropyl methylcellulose/polyvinyl alcohol (50/50) blends, which results from the homogeneous dispersion of fillers into the polymer matrix. The results indicate that these nanocomposites have a potential to meet the technological demands of high-k dielectrics and/or embedded capacitors.     

Influence of Dose on Particle Size and Optical Properties of Colloidal Platinum Nanoparticles

Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size.     

Different Storage Conditions Influence Biocompatibility and Physicochemical Properties of Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic properties, stability and biocompatibility of the particles. A good knowledge of the effect of storage conditions on those parameters is of utmost importance for the translation of the therapy concept into the clinic and for reproducibility in preclinical studies. Here, core shell SPIONs with a hybrid coating consisting of lauric acid and albumin were stored at different temperatures from 4 to 45 °C over twelve weeks and periodically tested for their physicochemical properties over time. Surprisingly, even at the highest storage temperature we did not observe denaturation of the protein or colloidal instability. However, the saturation magnetisation decreased by maximally 28.8% with clear correlation to time and storage temperature. Furthermore, the biocompatibility was clearly affected, as cellular uptake of the SPIONs into human T-lymphoma cells was crucially dependent on the storage conditions. Taken together, the results show that the particle properties undergo significant changes over time depending on the way they are stored.     

Effect of Biologically Active Polymer Compounds on the Supramolecular Structure of Polyvinyl Alcohol Films

The supramolecular structure of polyvinyl alcohol films containing the proteolytic enzyme protease C, polyhexamethyleneguanidine salt as antimicrobial, and sodium alginate and/or tetraborate was investigated by electron microscopy and differential scanning calorimetry. The plasticizing effect of the biologically substances and determining effect of the conformation of polyhexamethyleneguanidine salt on the supramolecular structure of polyvinyl alcohol films was demonstrated.     

增塑剂改性聚乙烯醇的熔融加工性能研究

在聚乙烯醇(PVA)中加入二乙醇胺/一缩二乙二醇复合增塑剂,通过熔融挤出制备了PVA改性材料。采用傅里叶光谱仪、差示扫描量热仪、X射线衍射仪等研究了复合增塑剂对PVA拉伸性能、熔体的流动速率、表观黏度及微晶尺寸的影响,结果表明:增塑剂用量在30 phr以上时,PVA的熔体流动速率大幅增加,表观黏度降低,氢键作用减弱,结晶度和熔点明显下降。