Convenient approach of nanohydroxyapatite polymeric matrix composites

Polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) were used to prepare polymeric matrix composites of nanohydroxyapatite (HAV and HAP), respectively, by using a biomimetic approach under 100 °C. A comparison with synthetic nanohydroxyapatite prepared by precipitation (SHA) was evaluated. Characterization of the prepared powders by differential thermal analysis (DTA) and thermogravimetric analysis (TGA) was achieved, X-ray diffraction (XRD), scanning electron microscope (SEM) with elemental analysis by (EDS) and inductively coupled plasma-optical emission spectrometer were used. DTA and TG showed the weight loss in the 400–1200 °C was almost attributed to carbonate decomposition which appeared apparently in the polymer associated samples due to the decomposition of polymer matrix. X-ray diffraction confirmed mainly the formation of hydroxyapatite. Specific surface area (BET) and scanning electron microscope and scanning electron microscopy (SEM) confirmed the range of nanosized of the prepared HA samples. The polymer matrix prefers orientation of the particles to rod-like shape. Elemental analysis showed mainly, Ca, P, C and O ions besides Na and Cl. Inductively coupled plasma showed the composition and the Ca/P atomic ratio of all samples ranging between 1.72 and 1.85.     

Polycaprolactone-blended gelatin microspheres and their morphological study

Polycaprolactone (PCL)-blended gelatin microspheres were prepared in the size ranges of 5–20 μm as well as 70–340 μm and modified through different compositions of PCL to gelatin in the oil-in-water emulsion solvent evaporation method. The formation of the polymer particles and particle morphology, stability, crystallinity, and thermal behavior of the polymer blends were studied. The changes in physiochemical properties of the blends were also studied with the addition of very less amount of polyvinylpyrrolidone (PVP), as it enhances the particle size distribution of microspheres as well as the surface morphology. Differential scanning calorimetry analysis shows the shifting of exothermic peak in the PCL/gelatin blend, and the PCL/gelatin blend stabilized by PVP results in the decrease in crystallinity. PCL-blended gelatin microspheres were smooth with definite shape and fine dispersibility with the increased concentration of gelatin to the polymer while lower concentration of the gelatin caused agglomeration. Optimization of the gelatin and PVP ratio to the polymer matrix results in large-size spherical stable microparticles. The stabilizing ability of microsphere decreases with the increased concentration of PCL during the solvent evaporation method. The addition of PVP to the PCL/gelatin blend enhanced the particle size distribution of microspheres as well as the surface morphology.     

O’O-月桂酰壳聚糖/聚乙烯吡咯烷酮网络凝胶的制备及释药作用

把壳聚糖改性成O’O-月桂酰壳聚糖,并通过交联法制备了O’O-月桂酰壳聚糖/聚乙烯吡咯烷酮(O’O-LCS/PVP)水凝胶,研究了聚乙烯吡咯烷酮质量比、反应温度、反应时间对水凝胶溶胀性能的影响,通过红外光谱法比较了CS和O’O-LCS结构上的不同。以布洛芬为模型药物研究了其释药性能。     

Natural hydroxyapatite—its behaviour during heat treatment

Natural origin hydroxyapatite (HAp) was extracted from animal bones by their treatment with hot NaOH solution. The remaining organic material oxidized in air atmosphere at moderate temperatures. In the material of this kind carbonate groups and small amounts of magnesium were found, usually not present in the synthetic HAp. Ca/P ratio in pig cortical bones was higher than that in the stoichiometric (synthetic) material. Fraction of carbonate groups decreased with temperature and CaO appeared at higher temperatures, but structure of hydroxyapatite became preserved even at 1000 °C, the highest temperature applied in this investigation. At temperatures >700 °C crystallite growth became intensive, specific surface area of the powder decreased and compacts of such powder started to shrink. Biological test showed that CAL-72 (human osteosarcoma) cells growth depended on heat treatment temperature of the natural HAp substrate.     

聚乙烯吡咯烷酮调控合成特殊形貌碳酸铈

以硝酸铈[Ce(NO₃)₃]为原料,碳酸氢铵（NH₄HCO₃）为沉淀剂,弱阳离子表面活性剂聚乙烯吡咯烷酮（PVP）为软模板剂,通过控制初始PVP浓度、加料反应时间、陈化时间制备得到颗粒均匀、类似花状结构的碳酸铈[Ce₂(CO₃)₃]粒子。采用扫描电子显微镜（SEM）、X射线衍射仪（XRD）、傅里叶红外光谱仪（FTIR）对制得的碳酸铈样品进行分析表征。结果表明,制备颗粒均匀、形状规则的花状碳酸铈粒子的最佳条件为：初始PVP浓度为2g/L,加料反应时间为1h,搅拌速度为300r/min,陈化时间为4h。并对PVP调控合成特殊形貌碳酸铈的调控机理进行了初步探究：PVP 通过酮基中的O吸附在碳酸铈晶体表面,阻碍了(002)和(040)晶面的生长,限制了晶体晶面的生长速度,从而调控碳酸铈的形貌。XRD结果表明最终产物为八水合碳酸铈。     

PA6/聚苯胺复合材料的研制

通过共混、原位聚合方法制备尼龙(PA)6/聚苯胺(PANI)复合材料,并利用不同的改性剂改性PA6/PANI复合材料.结果表明,改性复合材料中PANI的微观结构为纳米结构.当采用复合改性剂十六烷基三甲基溴化胺(CTAB)、1,5-萘二磺酸(1,5-NDA)改性PA6/PANI复合材料时,PANI的分散性最好,且具有较均一的纳米球结构.与未改性PA6/PANI复合材料相比,CTAB-1,5-NDA改性复合材料的电导率有显著提高,当PANI质量分数分别为20%、40%时,复合材料的室温电导率分别可达4.64×10-2S/cm和0.13 S/cm,该复合材料在电极材料方面具有广阔的开发和应用前景.     

Concentration of gelatin solution with polyethersulfone ultrafiltration membranes

In this work, polyethersulfone (PES) flat sheet ultrafiltration (UF) membranes were prepared by immersion precipitation phase inversion process with polyvinylpyrrolidone (PVP 30K) and acetone as additives. The best preparation condition for PES membranes with high water flux and rejection (to BSA) was decided. It was found that the optimal composition of the polymer casting solution was: 16 wt% (PES), 2 wt% (PVP 30K), and 1 wt% (acetone). Pure water flux of the membrane prepared at this condition reached to 373 L/m² h at 0.1 MPa, and the rejection to BSA was 91%. Compared with other reports, the rejection was slightly low but the flux of the PES membrane was high. When the membrane was used to concentrate gelatin solutions, the rejection value was over 75%. It was found that increasing the feed temperature and transmembrane pressure enhanced the permeation flux, but the rejection decreased slightly. However, increasing the cross-flow velocity of the feed solution simultaneously increased both the permeation flux and the rejection.     

Synthesis of hydroxyapatite fibers using electrospinning: A study of phase evolution based on polymer matrix

Hydroxyapatite (HA) is considered as the most promising biomaterial candidate to replace and regenerate hard tissues. A small amount of β-tricalcium phosphate (β-TCP) phase is advantageous for rapid bonding of the artificial bones to natural ones due to its high solubility compared to hydroxyapatite. Synthesizing HA nanofibers from electrospinning of sol-gel is considered as a widely researched topic. Motivation of the current work was to investigate the influence of polymeric binder in the final phase evolution after heat treatment of electrospun nanofibers. Calcium phosphate nanofibers were fabricated by electrospinning sols using gelatine and polyvinylpyrrolidone as carrier polymers and subjected to heat treatment. It was realized that carrier polymers facilitate preferential calcium phosphate phase formation by forming hydroxyapatite as major phase while PVP was used and β-TCP with HA as secondary phase while gelatine was employed. XRD and thermal analyses were performed to ascertain the reason behind this interesting behaviour.     

Preparation of LiNi0·6Co0·2Mn0·2O2 by PVP modified liquid-phase assisted solid-phase method and its electrochemical energy storage performance

During the preparation process of LiNi_0·6Co_0·2Mn_0·2O₂ (NCM622) material via solid-phase method, the obtained NCM622 particle size is often inconsistent due to the inhomogeneous phase mixing, which makes the NCM622 material have low specific capacity and poor rate performance, and thus restrict the application of solid-phase method. In order to solve this problem and make full use of the advantages of solid-phase method, liquid-phase assisted mixing is used to replace the traditional mechanical mixing. At the same time, polyvinylpyrrolidone (PVP) is introduced to control the crystal morphology and particle size, thus a NCM622 material with excellent electrochemical energy storage performance has been prepared by the PVP modified liquid-phase assisted solid-state method in this paper. X-ray diffraction, scanning electron microscopy and Raman spectroscopy are used to characterize the morphology structure of the obtained materials. Their electrochemical energy storage performance is tested by program-controlled battery tester and electrochemical workstation after being assembled into button cells. The research results show that with the introduction of PVP, the particle size of the obtained material becomes smaller, the particle size distribution is more uniform, and the degree of cation mixing is further reduced. When the PVP adding amount is up to 1.6 wt %, the obtained material shows the best electrochemical performance: its first discharge specific capacity and coulomb efficiency are 183.19 mAh.g⁻¹ and 88 % (0.1C), respectively. The capacity retention rate is 96.5 % after 100 cycles at 1C (half-cell system and laboratory conditions), which is comparable or better than those by other preparation methods, showing a good application prospect.     

盐酸浸取兽骨制备食品级磷酸氢钙

用盐酸浸取兽骨中的磷酸盐,通过脱色,中和,纯化,干燥等步骤制备了食品级磷酸氢钙,介绍了制备原理,工艺流程操作要点。     

羟基磷灰石/壳聚糖复合材料研究进展

综述了羟基磷灰石/壳聚糖复合材料的研究现状,对其制备、特点、性能进行了探讨,羟基磷灰石基人工骨作为最有前途的生物硬组织替代材料之一,在生物医用材料和医学研究领域有着广泛的应用前景。主要从化学的角度对材料复合、表征、应用进行了阐述。进而对壳聚糖/羟基磷灰石复合材料的研究发展前景予以展望。     

羟基磷灰石/聚乳酸复合材料制备的研究进展

聚乳酸是一类重要的生物降解聚合物,羟基磷灰石是人体骨骼的基本成分。以羟基磷灰石为增强材料、聚乳酸为基体制备的羟基磷灰石/聚乳酸复合材料,是无机/有机生物复合材料的典型代表,具有良好的力学性能与生物相容性,在很多领域有重要的应用。本文主要综述了羟基磷灰石/聚乳酸复合材料的制备方法。     

Improved dielectric properties and energy density of PVDF composites using PVP engineered BaTiO<Subscript>3</Subscript> nanoparticles

This work systematically investigates the effect of modifier polyvinylpyrrolidone (PVP) on the microstructure, dielectric and energy storage properties of BaTiO₃/PVDF composites. The results demonstrate that the BaTiO₃ nanoparticles modified by PVP are uniformly dispersed in the composites, and the defects including cracks and voids are obviously decreased in contrast to the composites with unmodified BaTiO₃ nanoparticles. Due to the enhanced interfacial polarization, the composites with BaTiO₃@PVP show improved dielectric properties compared with the composites with unmodified BaTiO₃ nanoparticles. For instance, at 1 kHz, the dielectric constant and dielectric loss of the composite with 50 vol% of BaTiO₃@PVP nanoparticles are 80.4 and 0.085, while of which the BaTiO₃/PVDF are 35 and 0.265, respectively. The discharge energy density of the composites is largely improved with PVP engineered BaTiO₃ nanoparticles. The composite with 30 vol% BaTiO₃@PVP achieves a discharged energy density of 4.06 J/cc at 240 kV/mm, which is 116% larger than that of pure PVDF (1.88 J/cc). This research provides an effect modifier to prepare high performance dielectric materials.     

Comparison of chitosan apatite composites synthesized by different methods

This article presents some results concerning chitosan apatite composites obtained by two different methods. First method is based on phosphorylation, calcification and soaking in different calcium phosphate growth media (1.5 × SBF (simulated body fluid), Ca‐PTris (calcium phosphorous tris) and the second method is based on mixing of calcium deficient apatite powder with a chitosan solution. This research is focused on studying and understanding the effect of using different methods on Ca:P ratio of composites. The Ca:P ratio of composites formed in 1.5 × SBF are closer to that of bone when compared with the Ca:P ratio of composites formed in Ca‐PTris solution and Ca:P ratio of composites formed by mixing of calcium deficient apatite powder with a chitosan solution. The Ca:P ratio of the composite (1.75) immersed in 1.5 × SBF for 35 day is similar to the theoretical value of hydroxyapatite (1.67) and equal to the theoretical value of human bone (1.75). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Synthesis and characterization of bioinspired nano-hydroxyapatite by wet chemical precipitation

In this work, nanometric hydroxyapatite was added with mineral traces naturally present in mammalian bones. It was synthesized by wet chemical precipitation using Ca(OH)₂ obtained from eggshells as a precursor. Subsequent calcination was performed at a low temperature of 250 °C to remove reaction by-products but avoiding the crystal size transition to micrometric sizes. Synthetic hydroxyapatite crystals exhibited irregular-spherical morphologies with a Feret's diameter ranging from 10 to 90 nm. Most importantly, this hydroxyapatite contains levels of Ca, Mg, P, Na, S, Sr, K, Si, Fe, Al, and Ba, close to those reported for mammalian bones. The analysis of the commercial synthetic hydroxyapatite revealed that its crystals form micrometric-like-flakes clusters that do not have additional ions but only Ca and P.     

Preparation and morphological investigation on bioactive ion-modified carbonated hydroxyapatite-biopolymer composite ceramics as coatings for orthopaedic implants

Bioactive ions (Mg, Sr, Zn) doped carbonated hydroxyapatite powders (dHAp) and pure carbonated hydroxyapatite (HAp) powders were prepared by wet chemical precipitation method. The bioactive ions were incorporated into the HAp matrix by co-precipitation from solution containing the appropriate amount of chloride salt of different ions. The morphology of pure HAp was mainly needle-like in nanometre size and the particles were disordered showing quasi-amorphous structure. The ion doping changed the morphology of particles, the dHAp particles had distorted spheroid shapes. Owing to the ion addition, the crystallinity of particles decreased. Particle aggregations can also be observed in both types of samples. HAp and dHAp loaded biopolymer polyvinylpyrrolidone (PVP) composite materials have also been developed by novel electrospinning technique. It has been shown that both the HAp and dHAp particles can be successfully incorporated into the PVP fibre web matrix and simultaneously the bioceramic powders were attached to the surface of polymer fibres. The surface of fibres was not fully covered with the particles. The ceramic powder addition to the polymer solution caused the polymer fibres to become more entangled and the diameters of fibres varied over a wider range compared to the base polymer fibres without bioceramic powder addition.     

High-flux PVDF/PVP nanocomposite ultrafiltration membrane incorporated with graphene oxide nanoribbones with improved antifouling properties

A novel polyvinylidene fluoride (PVDF) nanocomposite membrane containing graphene oxide nanoribbones (GONRs) as a new nanofiller and polyvinylpyrrolidone (PVP) as pore former agent was prepared via phase inversion method. GONRs were prepared by oxidative unzipping of multi-walled carbon nanotubes (MWCNTs) via chemical approach. Chemical vapor deposition method was used to synthesis MWCNTs. The effects of adding GONRs and PVP into the casting solution on morphology, hydrophilicity and pure water flux (PWF) of the prepared nanocomposite membranes were explored. Antifouling experiments were also performed. It was found that compared to the neat PVDF membrane, PWF of the PVDF/PVP, PVDF/(0.5GONRs) and PVDF/(0.5GONRs)/PVP membranes were improved 80%, 44.9%, and 241.6%, respectively. The obtained results showed that GONRs and PVP exhibit synergistic effects in controlling the membrane properties. This work shows that GONRs can be suitable as nanofiller for preparation of high performance PVDF ultrafiltration membranes with improved antifouling properties.     

Preparation and characterization of hydroxyapatite/chitosan–gelatin network composite

A novel composite composed of hydroxyapatite (HA) and a network formed via cocrosslinking of chitosan and gelatin with glutaraldehyde was developed. Two preparation methods are described in detail. A porous material, with similar organic–inorganic constituents to that of natural bone, was made by a unique sol–gel method. The formation of the network in the presence of HA was characterized using IR analysis. The morphology of the composites was also examined using SEM. In addition, XRD was applied to estimate the change in the component crystal. The results indicate that the presence of HA does not retard the formation of the chitosan/gelatin network. On the other hand, the polymer matrix has hardly any influence on the high crystallinity of HA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2929–2938, 2000     

聚砜平板超滤膜的制备及性能优化

采用相转化法制备聚砜(PSF)平板超滤膜,通过正交试验确定了较佳制膜条件和各影响因素对膜性能的影响程度(PSF含量>溶剂种类>PVP含量>蒸发时间).在综合考虑经济性和膜性能优化的前提下,由单因素试验探讨了PSF含量、添加剂聚乙烯吡咯烷酮(PVP)含量及第2种溶剂N-甲基吡咯烷酮、二甲基亚砜的添加量对膜性能的影响.结果表明,最优化制膜条件为:PSF和PVP的质量分数分别为13.5%和3%,溶剂为二甲基亚砜和二甲基甲酰胺混合物且体积比为1:5,蒸发时间为10 s.在此条件下,膜将保持原有高截留率并使纯水通量得到较大提高.     

Synthesis of intercalated lamellar hydroxyapatite/gelatin nanocomposite for bone substitute application

Hydroxyapatite (HAp)/polymer composites have been widely investigated for bone substitute applications in recent years. Inspired by the arrangement of ordered organic and inorganic layers in natural bones and seashells, for the first time a novel intercalated nanocomposite of gelatin and lamellar HAp was prepared via solution intercalation process. X‐ray diffraction (XRD) results showed that the basal spacing of HAp lamellas enlarged by 3.0 nm from 3.1 nm to 6.1 nm, indicating that the gelatin molecules had been intercalated into the gallery of lamellar HAp. The microstructures of pure lamellar HAp and intercalated gelatin/HAp nanocomposite were observed by transmission electron microscopy (TEM) analysis. Fourier transform infrared spectroscopy (FT‐IR) analysis revealed that there were chemical interactions between gelatin molecules and HAp. Thermogravimetric analysis (TGA) results confirmed that thermal stability of the composites was enhanced. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009