Synthesis and characterization of gelatin based polyester urethane scaffold

For tissue engineering purpose two gelatin based polyester urethane scaffolds of different compositions were prepared from lactic acid, polyethylene glycol 400 (PEG 400) and characterized by FTIR, XRD for their mechanical and morphological properties using SEM and optical microscopic analyses. Degradation and swelling studies of gelatin based polyester urethane scaffolds in phosphate buffer saline (PBS) were performed. Human keratinocyte cells were cultured within these scaffolds, which showed good cell adherence and proliferation.     

Properties of polymer networks prepared by blending polyester urethane acrylate with acrylated epoxidized soybean oil

Polyurethane network films were prepared using polyester urethane acrylate (PUA) having terminal double-bond functional groups and acrylated epoxidized soybean oil (AESO). PUA elastomers were prepared by reacting polyester diol with diisocyanates, hexamethylene diamine, and acrylic acid. PUA/AESO network blends are synthesized by a simultaneous thermal polymerization process. The physical and thermal properties of the polymer networks obtained from the blend of AESO and polyester urethane urea acrylate were studied using FTIR-ATR, the thermal degradation behavior was studied by thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and tensile properties measurements being applied. The measurements were compared to the results for elastomers made from the PUA. The weight ratios of PUA/AESO affected the thermal and mechanical properties. With an increase in AESO content, the glass-transition temperature of the networks decreased from 40 to −4.8 °C, tensile strength increased from 1.7 to 9.8 MPa, and elongation at break decreased from 470 to 70%.     

Effect of the solubility of antibiotics on their release from degradable polyurethane

Application of biodegradable polyester urethane, as a drug loading matrix in the form of a coating on implant devices was investigated. Polyester urethane films were loaded with model antibiotics, like rifampicin, gentamicin and ciprofloxacin and their release characteristics were evaluated in simulated body fluid. Effect of solubility of antibiotics and degradation of matrix on the drug release behavior of biodegradable polyester urethane coating was also studied. It was observed that antibiotics having hydrophilicity or lipophilicity same as that of polymer matrix provide an extended release with relatively less initial burst release. Effect of degradation of polymer matrix has a dual significance in this case and the drug release rate increases with the increase in degradation rate. A high initial burst release was observed for antibiotics having hydrophilicity or lipophilicity opposite to that of polyurethane matrix and hence in this case antibiotic release was not significantly controlled by degradation of matrix.     

Improvement of bis-GMA-based resins by urethane linkages: DTA and DSC thermal properties

Experimental bis-GMA/TEGDMA/urethane resins were investigated using synthesized urethane monomers to improve thermal properties. DTA (differential thermal analysis) results show that curing temperatures were 160 and 165°C in bis-GMA-based resins containing the synthetic 2 HEMA/N 3500 urethane monomer, 150°C in the resin containing the 2 HEMA/HT urethane monomer, and 153°C in the urethane monomer derived from 2 HEMA/N 3500. Also, DSC (differential scanning calorimetry) results show that the value of activation for polymerization during heating is lower in bis-GMA/TEGDMA containing synthesized urethane monomer (1.89, 2.44, 2.50 kcal/mol) than undiluted urethane monomer (7.50 kcal/mol) when these synthesized urethane monomers were diluted with bis-GMA/TEGDMA. With the use of urethane monomer as an additive to bis-GMA/TEGDMA it is possible to cure more rapidly with lower activation energy.     

含PCL和PBST链段聚酯聚氨酯的合成与表征

为提高PBS基脂肪族聚酯的综合性能,通过ε-己内酯的开环聚合制备了端羟基的聚己内酯(PCL-OH),再通过熔融缩聚法制备了端羟基的聚(丁二酸丁二醇酯对苯二甲酸丁二醇酯)无规共聚物(PBST-OH),用氢化MDI(H12MDI)作为扩链剂,制得了可生物降解的聚酯聚氧酯(PPCLBST).采用核磁共振谱和红外光谱确定了PP...     

Synthesis,extrusion and rheological behaviour of PU/HA composites for biomedical applications

Biostable polyurethane/hydroxyapatite (PU/HA) composites with potential application as bone replacement materials were synthesized in bulk and processed in a screw extruder. The polyurethanes (PU) were prepared by reacting an aliphatic diisocyanate, 4-methylene-bis-diisocyanate (MDI), with poly-(ε-caprolactone) (PCL) diols and polytetramethylene oxide (PTMO) of different molecular weights, extended with 1, 4-butanediol (BDO). Glass-transition temperatures were measured by differential scanning calorimetry (DSC). The specific PU groups were assessed by total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The effects of polymer chemistry and filler content on the rheological behaviour were studied by oscillatory rheometry. Polymers with larger chain lengths showed higher viscosity and, for identical chain lengths, polyether urethanes seem to have higher viscosities than polyester based urethanes. A lubricating effect was found for composites containing 50% weight of filler, whereas at higher filler contents a solid-like behaviour was measured. Polymer chemistry seems to be affected by ageing but not so by the presence of filler. Ageing is characterized by a decrease in the concentration of hydrogen bonds involving between urethane linkages.     

Anti-microbial and anti-corrosive poly (ester amide urethane) siloxane modified ZnO hybrid coatings from Thevetia peruviana seed oil

The utilization of renewable resources for the development of organic coatings is a viable means of creating alternatives to petroleum-based chemicals which are not eco-friendly. This paper reports the synthesis of polyesteramide–urethane–silica–zinc oxide hybrid coatings from Thevetia peruviana seed oil (TPSO). The periphery of ZnO nano-particles is modified with 3-aminopropyltrimethoxysilane to prepare silica grafted ZnO composite particles. The TPSO based polyesteramide was reacted with 4,4′-diisocyanatodicyclohexylmethane in presence of siloxane modified ZnO to obtain –NCO terminated polyesteramide–urethane–silica ZnO prepolymer. These hybrid pre-polymers were casted on tin foil and cured under atmospheric moisture to obtain eco-friendly, moisture cured polyesteramide–urethanes–silica–zinc oxide hybrid coating films. The synthesized polyester and polyurethane formation was confirmed by using FT-IR and NMR spectroscopic techniques. The resultant hybrid coating films were characterized by using FT-IR, TGA, DSC, SEM, corrosion resistance and microbial resistance. Results confirm that with increase of siloxane modified ZnO content in the polyurethane matrix thermal stability, glass transition temperature and corrosion resistance improved. The antibacterial activity shows that the hybrid films exhibit excellent resistance towards Escherichia coli and Staphylococcus aureus. The salt spray test on coated panel samples show good corrosion resistance properties.     

Sustained release of antibiotic from polyurethane coated implant materials

Implant associated infections are of increasing importance. To minimize the risks of implant-associated infections recent biomedical strategies have led to the modification of the medical device surfaces. The modifications are in the terms of increasing surface biocompatibility and decreasing bacterial adherence, which can be achieved by applying a coating of biocompatible polymer onto the said surfaces. Entrapping anti-infective agents in a polymer matrix provides an approach to kill bacteria and combat the possibility of any residual infection. We have prepared a biodegradable polyester urethane coat for implant materials, which have the property to accommodate antibiotics within itself. These polyurethane coating materials were characterized by FTIR spectroscopy, swelling property in SBF, gravimetric analysis, drug release, and biocompatibility study. Drug release rates, bacterial colonization and morphological features were also evaluated to predict and understand the antimicrobial activity of these delivery systems. Drug release characteristics were investigated and the physico-chemical mechanisms of the delivery were discussed. Results suggest that the polyester urethane can be used as an implant coating material and can be used as a matrix for the sustained delivery of anti-infective agent.     

Sustained release of antibiotic from polyurethane coated implant materials

Implant associated infections are of increasing importance. To minimize the risks of implant-associated infections recent biomedical strategies have led to the modification of the medical device surfaces. The modifications are in the terms of increasing surface biocompatibility and decreasing bacterial adherence, which can be achieved by applying a coating of biocompatible polymer onto the said surfaces. Entrapping anti-infective agents in a polymer matrix provides an approach to kill bacteria and combat the possibility of any residual infection. We have prepared a biodegradable polyester urethane coat for implant materials, which have the property to accommodate antibiotics within itself. These polyurethane coating materials were characterized by FTIR spectroscopy, swelling property in SBF, gravimetric analysis, drug release, and biocompatibility study. Drug release rates, bacterial colonization and morphological features were also evaluated to predict and understand the antimicrobial activity of these delivery systems. Drug release characteristics were investigated and the physico-chemical mechanisms of the delivery were discussed. Results suggest that the polyester urethane can be used as an implant coating material and can be used as a matrix for the sustained delivery of anti-infective agent.     

Synthesis,characterization, and thermal stability of novel poly(azomethine-urethane)s and polyphenol derivatives derived from 2,4-dihydroxy benzaldehyde and toluene-2,4-diisocyanate

Up to date, only a few kinds of poly(azomethine-urethane)s (PAMUs) were synthesized and studied with thermal degradation steps. However, polyphenol based PAMUs including azomethine linkages have not been investigated yet. The polyurethanes were prepared by condensation reaction of 2,4-dihydroxybenzaldehyde (2,4-DHBA) with toluene-2,4-diisocyanate (TDI) under argon atmosphere. Synthesized polyurethane was converted to its poly(azomethine urethane) species (TP-2AP, TP-3AP, and TP-4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s were converted to their polyphenol species (P-TP-2AP, P-TP-3AP, and P-TP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV–vis, ¹H NMR, and ¹³C NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA, and DSC. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities.     

端叠氮基超支化聚酯的合成与表征

以三羟甲基丙烷为核、对甲苯磺酸为催化剂,2,2-二羟甲基丙酸缩聚为端羟基超支化聚酯,端羟基先后经磺酰化改性和叠氮基取代后得到端叠氮基超支化聚酯。利用红外光谱、核磁共振、元素分析、凝胶色谱等方法对目标产物进行了结构表征和确认;在此基础上,对目标产品进行了热重(TG)和差示扫描量热(DSC)表征。结果表明:端叠氮基超支化聚酯的支化度为0.45;热分解分为两个阶段,分别是端叠氮基热分解(249.4℃)和主链热分解(350℃);玻璃化转变温度为-55.2℃。     

Highly transparent polymer substrates for flexible displays using semi-interconnected interpenetrating polymer networks

Semi-interconnected interpenetrating polymer networks (SIPNs) based on unsaturated polyurethane (UP) and different monomers, including styrene and acrylate with an UP ratio of 50 wt%, were synthesized. The resulting SIPN films exhibited excellent optical transparency in the visible range with > 90% transmittance at 400 nm. The glass transition temperature (Tg) varied in the range of 100 approximately 135 degrees C depending on the unsaturated monomers introduced. They also had good flexibility compared to the conventional rigid polystyrene or polyacrylate due to the homogeneously dispersed elastic urethane moiety in the SIPNs. Below the glass transition temperature (Tg) of the SIPN substrates, the ITO-grown SIPN films exhibited good electrical and optical properties, showing potential as a promising substrate in flexible display applications.     

Microstructure and properties of polyester/urethane acrylate thermosetting blends,and their use as composite matrices

Thermosetting blends of a rigid polyester (PE) and a poly(urethane acrylate) elastomer (UA) have been investigated over a wide range of compositions in the cast condition, and in use as matrices of unidirectional glass-fibre composites. Transmission electron microscopy showed that blends in the composition range 20%–60% UA have a two-phase structure, probably with a phase inversion from PE-rich to UA-rich matrix between 40% and 50% UA. It was found that the observed variation in Young's modulus with blend composition could be represented by a simple geometrical model based on series/parallel combination of phases with a regular dispersion. This analysis provided supporting evidence for the proposed phase structures of the blends. Further evidence as to the phase structures was the rapid decline in indentation hardness and in temperature of distortion under load which occurred between 40% and 50% UA. Blends with up to 15% UA were found to have higher tensile strength, and slightly higher failure strain, than the unblended polyester. For composites with PE-rich matrices, the transverse Young's modulus exceeded that of the matrix in bulk, and it was found that the relationship could be expressed approximately by a version of the series/parallel model referred to above. Transverse tensile strengths of the composites were, in all cases, lower than the bulk matrix strength. To account for the observed relationship, a modified version of the Cooper and Kelly model for transverse strength is presented.     

聚酯增塑剂的合成及对PVC的增塑

通过熔融缩聚的方法,合成了己二酸丙二醇型聚酯增塑剂,将其作为辅助增塑剂用于软质PVC的制备,期望达到降低聚氯乙烯(PVC)主增塑剂邻苯二甲酸二辛酯(DOP)迁移和抽出的目的。通过引入第三单体三羟甲基丙烷,并控制第三单体的加入量,合成了具有不同支化度的聚酯,并对PVC进行增塑试验,考察了聚酯的支化度及相对分子质量对PVC增塑效果的影响。实验结果表明,所合成的不同分子量聚酯增塑剂与PVC树脂的相容性均良好,当采用较高分子量聚酯或较低支化度聚酯时,其增塑PVC材料的玻璃化转变温度较低,所显示的增塑效率较高,材料的热稳定性能较好。     

芳香族超支化聚酯的合成及表征

以三羟甲基丙烷为核单体,双酚酸甲酯为AB2型单体,采用熔融缩聚的方法合成了具有芳香型结构的超支化聚酯.使用IR、黏度、化学滴定、热重分析等方法进行了表征.结果表明,合成芳香族超支化聚酯为多端羟基的类球型聚酯,具有较好的流动性和热稳定性,可作为加工助剂用于改善体系加工性能.     

芳香族超支化聚酯型环氧树脂的合成及表征

以三羟甲基丙烷为中心核,与偏苯三酸酐和环氧氯丙烷开环聚合反应合成芳香族超支化聚酯,在碳酸钾水溶液作用下对其进行了闭环反应合成了超支化聚酯型环氧树脂。分别用红外光谱、核磁氢谱、凝胶色谱仪、热重分析表征了超支化聚酯型环氧树脂的结构。结果表明,合成产物具有芳香族超支化聚酯型环氧分子结构,合成的芳香族超支化聚酯型环氧树脂具有较好的热稳定性。     

Kinetics of the humid aging of magnetic recording tape

The kinetics of the hydrolysis of polyester urethane binders of magnetic recording tape is described. Kinetic data were generated from measurements of acetone-extractable hydrolyzed binder products versus time for various humidity-temperature environments. These data can be described by a linear, single product, reversible rate equation. This equation, coupled with measurements on the effect of hydrolysis on recorded tape performance, is used to predict proper environmental storage conditions for magnetic tape.     

Properties of Reactive Magnetron Sputtered ITO Films without in-situ Substrate Heating and Post-deposition Annealing

1. Introductiontransparent conductive indium tin oxide (ITO)films have been extensively used in a variety of electronic and opto--electronic applications because oftheir high transmission in the visible range, high infrared (IR) reflection, and low electrical resistivity.A variety of deposition techniques have been appliedto fabricate ITO films such as CVD, spray pyrolysisand sputteringll'2]. However, sputtering is the mostextensively used technique especially in industry. Recelltly, targe…     

Preparation of PEG-grafted silica particles using emulsion method

Low-molecular-weight poly(ethylene glycol) (PEG) was grafted onto the surface of silica particles by a two-step addition process. To prepare PEG-grafted silica particles, PEGME–IPTES monomers were synthesized by the reaction of 3-(triethoxysilyl)propyl isocyanate (IPTES) with poly(ethylene glycol) methyl ether (PEGME) in the presence of dibutyltin dilaurate. To remove PEGME residues, excessive IPTES was added to the solution. The peak for a urethane carbonyl group of PEGME–IPTES was observed at 1722 cm⁻¹ by FT-IR spectroscopy. Through the sequential addition of TEOS and PEGME–IPTES monomers, PEG was introduced onto the surface of silica particles. The introduction of PEG onto the surface was observed by SEM, Brunauer–Emmett–Teller (BET), and FT-IR spectroscopy. When PEG was grafted onto the surface of silica particles, the surface area of silica particles decreased and the average pore diameter increased. The peak for urethane carbonyl group and alkyl group of PEG appeared at 1722 cm⁻¹ and 2920 cm⁻¹.     

Effect of water immersion on the interlaminar and flexural performance of low cost liquid resin infused carbon fabric composites

This study investigates some potential benefits of using non-epoxy matrices in carbon fibre composites, targeting specific marine and wind energy applications. Water uptake during and after immersion for up to 28 days in deionised water at 40 °C, and the effects of such conditioning on the interlaminar shear and flexural performance of the composites with isophthalic polyester, vinyl ester and urethane acrylate matrices were compared to those of equivalent composites impregnated with three grades of epoxy resin. Results demonstrated that, although the epoxy systems perform equally or better than the alternative resins in the dry state, they are also more sensitive to property degradation due to water ingress. The relatively lower water absorption and subsequent limited reduction in performance of vinyl ester and urethane acrylate composites is sufficiently promising to justify further study.