Morphology and electrical properties of hybrid and sulphonated oxalic acid-doped polyaniline

Polyaniline–polyethylene glycol2000 (PAni–PEG2000) hybrid and sulphonated polyaniline (SPAni) were prepared using oxalic acid as dopant and potassium permanganate as oxidant. The properties of these two conductive polymers were studied in comparison with pure polyaniline (PAni) prepared using the same conditions. The investigated polymers were characterized using FTIR, UV–vis, TGA, TEM, SEM, XRD and their electrical conductivities were also investigated. The morphology of pure polymer was found to be flat ribbon-like form, while presence of polyethylene glycol led to the formation of separate nanospheres. The three polymer samples have different degrees of crystallinity, the highest degree is for SPAni. Unexpectedly, electrical conductivity is in the order SPAni > PAni–PEG2000 > PAni, aging of PAni increases gradually the conductivity of the polymer from 0.0056 to 0.023 S cm^?1 and the increase of temperature gradually decreases the conductivity.     

Drug distribution within poly(ɛ-caprolactone) microspheres and in vitro release

Poly(?-caprolactone) (PCL) microspheres loaded two model compounds (p-nitroaniline and rhodamine B) with different water solubilities were prepared by an s/o/w single emulsion solvent evaporation method. The microspheres morphology was investigated by scanning electron microscopy, drug loading and encapsulation efficiency were calculated. Drug distribution within microsphere matrix was studied by confocal laser scanning microscopy. p-Nitroaniline, as a more hydrophobic compound, distributed more evenly in the matrix, while the more hydrophilic compound rhodamine distributed close to the surfaces of microspheres. The in vitro release profiles therefore were different. This study helps to further understand the drug release mechanism from microsphere matrix, and design effective long-term drug delivery system.     

Atomic layer deposition of TiO<Subscript>2</Subscript> thin films on nanoporous alumina templates: Medical applications

Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of a nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Neither the 20 nm nor the 100 nm TiO₂-coated nanoporous alumina membranes exhibited statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. Nanostructured materials prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for “smart” drug delivery devices, orthopedic implants, or self-sterilizing medical devices.     

Polyterthiophene as an electrostimulated controlled drug release material of therapeutic levels of dexamethasone

Polyterthiophene has been investigated as a substrate for the controlled release of dexamethasone, a synthetic glucocorticoid anti-inflammatory drug, which is widely used to help reduce inflammation in the central nervous system. Dexamethasone was incorporated into the polymer as an anionic dopant during electrochemical polymerisation from water–acetonitrile solutions. Optimal polymer synthesis conditions were established to yield reproducible dexamethasone release profiles into a simulated physiological receiving solution. A homogeneous morphology of the polyterthiophene substrate with minimal extraneous features was observed to be critical for achieving reproducibility of release. Release profiles were established using a range of electrochemical stimulation protocols over a 24 h time period. The amount of dexamethasone released from the polyterthiophene under all electrostimulation protocols was at therapeutically relevant levels, with a maximum release of ～80 μg/cm² achieved when the polymer film was in a reduced state. The oxidation state of the polyterthiophene was found to be critical for controlled release of the dexamethasone. Polyterthiophene doped with dexamethasone was observed to auto-reduce when placed into the receiving solution. As a consequence, no significant difference was observed between the unstimulated (auto-reduced) polymer and the electrochemically reduced polyterthiophene. By electrochemically holding the polyterthiophene in the oxidised state, the rate of release of dexamethasone was significantly impeded with ～40 μg/cm² released over a 24 h period.     

Magnesium Octa[(4'-Benzo-15-Crown-5)-Oxy]Phthalocyaninate in Low-Molecular Hydrogels: Spectral Properties and Release under Stimulation

This work is dedicated to low-molecular hydrogels based on biodegradable sodium deoxycholate (SDC) and lysine hydrochloride (lys × HCl) with magnesium octa-[(4'-benzo-15-crown-5)-oxy]phthalocyaninate (Mgcr₈Pc) as the active component, namely, their synthesis, spectral properties of gel-solubilized Mgcr₈Pc, its release from the gel etc. Addition of Mgcr₈Pc occurs both via the mixing of the components and via its diffusion from the aqueous solution into the phase of the formed SDC/lys × HCl gel. Mgcr₈Pc-containing hydrogels are thermoreversible. The state of Mgcr₈Pc in the SDC/lys × HCl/NaCl gel at the room temperature and in the melt is studied using spectral methods. Gel melting releases Mgcr₈Pc in the form of a micelle-bound monomer. The presence of the Mgcr₈Pc monomer phase in the phthalocyanine-carrying supramolecular hydrogel causes fluorescent activity of the latter.     

Filling modes of polymer during submicron and nano-fabrication near glass transition temperature

In this study, we used a glass mold coated with TiN layer to fabricate submicron and nano-gratings on a PMMA (polymethylmethacrylate) film. The cavities on the mold, with sizes varying from 71 nm to 980 nm, was etched by ion beam. The deformation and filling modes of polymer during fabrication process were studied. Dual-peak deformations, which were considered as the characteristic filling modes of “viscous-dominant” polymer, were observed. Because our fabrication experiments were conducted near the glass transition temperature (T_g) of PMMA at which the polymer was “elastic–plastic-dominant”, the appearance of the dual-peak filling mode meant solid-state polymer might exhibit some characters of fluidic polymer at submicron and nano-scale. In addition, we presented a simple and effective mold release process at the end of this paper, which could reduce defects during molding release process.     

Bonding mechanism and interface characterisation during dissimilar friction stir welding of an aluminium/polymer bi-material joint

In the present study, detailed microstructural characterisation of a friction-stir-welded joint between AA5059 alloy and high-density polyethylene was carried out using field-emission scanning and high-resolution-transmission electron microscopy analysis. The structural features indicate large numbers of macro-, micro- and nano-mechanical interlocks between the Al-fragments and melted/re-solidified polymer matrix at the stir zone of the joint, with a 30-nm thick semi-crystalline aluminium structure layer elevated in levels of O, and traces of C at the interface. An ultrafine-grained structure with an average cell size of <100?nm was formed for the embedded Al-alloy fragments in the polymer matrix, as a result of low-temperature severe plastic deformation during friction-stir welding process. The interfacial chemical reactions assisted by generation of nano-scale pores inside the metal surface at the interface and secondary Van der Waals bonding are suggested as the main joining mechanisms, leading to significant improvements in the mechanical properties.     

PEDOT/PSS bending actuators for autofocus micro lens applications

This paper reports on the development of micro autofocus lens actuators using conducting polymer actuators. We propose a hydrophilic treatment for polyvinylidene difluoride (PVDF) membranes and a polyethylenedioxythiophene/poly(styrene sulfonic acid) (PEDOT/PSS) casting method for easily producing bending conducting polymer actuators with high mechanical strength.We first designed micro autofocus lens actuators using bending conducting polymer actuators, and then determined experimentally that the electrical conductivity and breaking strain of the PEDOT/PSS films could be improved by the addition of polyethylene oxide (PEO). Furthermore, we made hydrophobic PVDF membrane surfaces hydrophilic using polyethylene glycol methacrylate (PEGMA) and coated a solution of a mixture of PEDOT/PSS and PEO on the membrane surfaces to form a laminated film. We produced bending conducting polymer actuators by processing this film. Tests simulating the actuator's use in micro autofocus lenses showed the actuators to operate stably for more than a million cycles.     

Organic Dye Degradation Under Solar Irradiation by Hydrothermally Synthesized ZnS Nanospheres

The green synthesis of ZnS nanospheres using Citrus limetta (sweet lime) juice as a capping agent through a conventional hydrothermal method was studied. The particle size, morphology, chemical composition, band gap, and optical properties of the synthesized ZnS nanospheres were characterized using x-ray diffraction spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and ultraviolet–visible spectroscopy. The photocatalytic activity of the ZnS nanospheres was evaluated by degradation of rhodamine B (RhB) and methyl orange (MO) under solar irradiation. Upon 150 min of solar irradiation, the extent of degradation was 94% and 77% for RhB and MO, respectively.     

Corrosion and biocompatibility of PPy/PEG coating electrodeposited on Ti6Al7Nb alloy

This work aims to improve the corrosion rate of Ti6Al7Nb alloy and to increase its biocompatibility at the same time, obtaining polymer composite films based on polypyrrole/polyethylene glycol (PPy/PEG). The elaboration method was electrodeposition. FT‐IR analysis was performed in order to emphasize the formation of the PPy‐PEG composite film by incorporating PEG into the polymer structure. The paper is focussed on PEG (400 molecular weight) effect on the corrosion in bioliquids (as tested electrochemical bioliquid was chosen Hank's balanced salt solution) and on the biocompatibility properties. The PPy film significantly improves the biocompatibility of the Ti6Al7Nb alloy. The PEG presence in the polymerization solution leads to more stable composite polymer films on the titanium alloy surface with a better corrosion resistance and a more hydrophilic behaviour comparing with the PPy film. The increase of cell viability and proliferation potential as compared to the PPy film is not important.     

水凝胶在腐蚀防护领域应用进展综述

水凝胶材料由于其独特的含水交联网络结构,具有优越的亲水、润滑、耐磨、生物相容等特性,是近年来发展极为迅速的高分子材料之一,被广泛用于药物传输、软体机器人、可植入器官、传感器等生物医学等工程领域。在腐蚀防护领域,水凝胶材料由于其独特性质逐渐受到学者的关注,成为了新兴腐蚀防护材料之一。通过文献综述的方法,对化学交联法与物理交联法两种水凝胶的主要制备方法进行对比,对两种方法制备的水凝胶材料的结构和性质进行了对比,进一步分析了水凝胶材料具有的独特性质,及其在腐蚀防护领域的应用潜力。其中化学交联制备出的水凝胶,其稳定性好,力学强度高,具有良好的耐磨防污性,可制备出性能优异的海洋防污涂层。物理交联制备的水凝胶由于其内部具有三维网络空间结构可负载缓蚀剂,且其内部存在大量的动态可逆键,具有环境响应性,能随着环境pH、温度等变化而改变自身溶胀程度,从而改变负载在水凝胶中的缓蚀剂的释放速率。因此,对比传统固体缓蚀剂和液体缓蚀剂,水凝胶智能缓蚀剂对金属有着更长效的腐蚀防护性能,具有良好的应用前景。根据水凝胶材料的独特性质,着重分析了水凝胶材料在腐蚀防护领域的应用现状,并对研究前景进行了分析。目前制备水凝胶涂...     

Fabrication of Mono-dispersed Hollow Titania Nanospheres with Enhanced Photocatalytic Property

采用阳离子聚苯乙烯(PS)微球为模板,以钛酸丁酯为前驱体经溶胶凝胶反应制备了TiO2/PS复合微球,并经高温煅烧得到单分散中空TiO2纳米微球。采用扫描电镜(SEM)、透射电镜(TEM)、红外光谱仪(FT-IR)、X射线衍射仪(XRD)和紫外-可见分光光度计(UV-VIS DRS)对复合和中空微球的结构和光催化性能进行了表征。结果表明,经高温煅烧后TiO2中空微球尺寸相对于复合微球收缩了约25%,其粒径约为100 nm;中空微球壳层厚度可随钛酸丁酯用量而变化,壳层呈锐钛矿和金红石混晶结构,同时中空微球表现出比P25纳米TiO2更强的甲基橙光降解特性。     

Nanoscale smooth interface maintained metallisation of polyimide using low concentration ozone micro–nano bubbles dispersed in water

In order to induce adhesion of electroless CuNiP deposition to polyimide (PI) film substrate, surface modification of PI film with an aqueous dispersion of ozone micro–nano bubbles was investigated. The treatment resulted in maximum adhesion strength of 1·14 kN m^?1 for a treatment time of 5 min. Structure of the modified PI surface, the PI/plating interface, mechanism for adhesion and laminate properties were analysed. Despite increased adhesion, surface roughness of PI was not notably changed by the ozone induced surface modification. Contact of PI surface with high ozone concentration micro–nano bubbles with sufficient frequency was found to modify the surface with a low total ozone concentration of the aqueous dispersion. Cross-sectional observation of the interface suggested that formation of a thin nanoporous anchor layer on the PI surface was responsible for plating adhesion. This method provides an environment friendly and improved process for plating on PI using low concentration ozone treatment.     

Thermal Spraying of Bioactive Polymer Coatings for Orthopaedic Applications

Flame sprayed biocompatible polymer coatings, made of biodegradable and non-biodegradable polymers, were investigated as single coatings on titanium and as top coatings on plasma sprayed Hydroxyapatite. Biocompatible polymers can act as drug carriers for localized drug release following implantation. The polymer matrix consisted of a biodegradable polymer, polyhydroxybutyrate 98%/ polyhydroxyvalerate 2% (PHBV) and a non-biodegradable polymer, polymethylmethacrylate (PMMA). Screening tests were performed to determine the suitable range of spraying parameters, followed by a Design of Experiments study to determine the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), and to optimize the coating properties accordingly. Coatings characterization showed that optimized flame sprayed biocompatible polymers underwent little chemical degradation, did not produce acidic by-products in vitro, and that cells proliferated well on their surface.     

Fabrication and characterization of copper nanoparticles in PVA/PAAm IPNs and swelling of the resulting nanocomposites

Well-dispersed copper nanoparticles were fabricated using poly(vinyl alcohol)/polyacrylamide interpenetrating polymer networks (PVA/PAAm IPNs) as a nanoreactor template. The synthesis of the IPNs hydrogels was achieved in the presence of glutaraldehyde and N,N′-methylene-bis-acrylamide. The resulting PVA/PAAm/Cu nanocomposite hydrogels were characterized, and the swelling and mechanical properties were investigated. The results indicated that the copper nanoparticles had a spherical shape with a size range from 10 to 20 nm. The complexation of PVA in PVA/PAAm IPNs with Cu²⁺ played an important role in avoiding the aggregation of copper nanoparticles and providing particle size and size distribution controllability and stability. Although the swelling capacity of the nanocomposite hydrogels was slightly lower than that of the control, they had better compression mechanical properties. The water uptake and mechanical properties can be easily tuned by changing the component ratios to meet the requirements of specific applications, such as drug controlled release or tissue engineering.     

Calcium phosphate ceramics in drug delivery

Calcium phosphate (CaP) particulates, cements and scaffolds have attracted significant interest as drug delivery vehicles. CaP systems, including both hydroxyapaptite and tricalcium phosphates, possess variable stoichiometry, functionality and dissolution properties which make them suitable for cellular delivery. Their chemical similarity to bone and thus biocompatibility, as well as variable surface charge density contribute to their controlled release properties. Among specific research areas, nanoparticle size, morphology, surface area due to porosity, and chemistry controlled release kinetics are the most active. This article discusses CaP systems in their particulate, cements, and scaffold forms for drug, protein, and growth factor delivery toward orthopedic and dental applications.     

金刚石颗粒在水体系中的分散性能研究

金刚石颗粒在化学镀液介质中的稳定分散是实现复合镀工艺的先决条件.本文测定了金刚石颗粒悬浮液体系中颗粒的Zeta电位和粒径,探索了无机电解质类分散剂(SHP)和非离子型表面活性剂(PEG)对金刚石颗粒在水体系中表面动电位和粒径的影响.研究结果发现,随着SHP含量的增加,体系中金刚石颗粒表面的Zeta电位绝对值出现先增大后...     

On the use of conducting polymers to improve the resistance against corrosion of paints based on polyurethane resins

This work analyzes the physical properties of several paints and the resistance against corrosion that they impart after being modified by adding a conducting polymer. Five different formulations were selected: four polyurethane resins (two varnish and two aqueous based) and one multicomponent system containing polyester, melamine and cellulose acetobutyrate. The physical properties of the coatings were examined by FTIR, thermal analyses and viscosity measurements. Corrosion resistance of carbon steel coated with these paints was studied by means of accelerated laboratory tests. The results provided by the original formulations and those modified by adding 1 % w/w of polypyrrole or poly(3‐decylthiophene‐2,5‐diyl) regioregular were compared. Although the general behavior was irregular, showing dependence with the paint formulation, excellent results were achieved for an aqueous based polyurethane resin modified with polypyrrole. Accelerated immersion experiments in salt and acid solutions showed fast degradation of the film without conducting polymer, while the polymeric film with polypyrrole offered a higher resistance.     

乙酰半胱氨酸纳米微球药动学及药效学评价

目的: 对制备乙酰半胱氨酸纳米微球进行药动学和药效学评价。方法: 尾静脉注射乙酰半胱氨酸纳米微球和乙酰半胱氨酸,不同时间检测血浆和各脏器的乙酰半胱氨酸。通过皮下注射CCl₄建立大鼠肝损伤模型,不同剂量乙酰半胱氨酸纳米微球进行治疗,检测血清学指标和肝组织各项指标评价纳米微球治疗慢性肝损伤的疗效。结果: 乙酰半胱氨酸纳米微球改变了药物在体内的分布,肝组织中药物浓度明显提高,半衰期显著增加。药效实验显示,纳米微球能降低血清学指标,提高肝组织抗氧化功能,减轻肝细胞脂肪变性、细胞浸润和坏死。结论: 乙酰半胱氨酸纳米微球具有明显肝靶向性,有利于肝损伤的药物治疗,是一种比较理想的乙酰半胱氨酸新剂型。     

Electrospun poly(vinyl alcohol) nanofibers incorporating PEGylated multi-wall carbon nanotube

Recently, the fabrication of polymer composite nanofibers containing multi-wall carbon nanotube (MWCNT) by electrospinning has attracted much attention due to their potential advantages for the enhancement of properties such as electrical and thermal conductivity. In order to utilize the superior properties of MWCNT, in this study, MWCNT was covalently grafted with poly(ethylene glycol) (PEG) chains and PEGylated MWCNT-incorporated PVA nanofibers were prepared by electrospinning. To do so, MWCNT was firstly chemically oxidized to bear carboxyl groups and successively reacted with PEG molecules in ethanol. The PEGylated MWCNT was mixed with aqueous PVA solution and electrospinning was performed. The degree of surface modification of MWCNT by PEG was thoroughly investigated by FT-IR, XPS and TGA. Compared to the pristine MWCNT, the PEGylated MWCNT was uniformly dispersed PVA nanofibers without agglomeration. Because of the enhanced dispersion of PEGylated MWCNT in PVA nanofibers, the electrical conductivity of nanofibers with PEGylated MWCNT (1.0 wt%) was increased by 4 orders of magnitude compared to that of nanofibers with pristine MWCNT (1.0 wt%).