共查询到19条相似文献,搜索用时 93 毫秒
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聚磷酸酯—聚氨酯药物释放材料的合成 总被引:4,自引:0,他引:4
报道了一类新型生物可降解和生物相容性药物释放材料聚磷酸酯-聚氨酯的合成和表征,研究了这类聚合物的体外降解及其对牛血清白蛋白的释放性能。 相似文献
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二氧化碳共聚物为基聚氨酯的生物降解性研究 总被引:5,自引:0,他引:5
以CO2为起始物合成生物降解型聚合物,既能利用丰富的CO2资源,减轻温室效应;又能减轻聚合物垃圾造成的污染。聚碳酸亚乙酯(PEC)经动物体内实验和土埋实验,证明具有良好的生物降解性[1,2]。由PEC合成的聚氨酯可获得有良好力学性能的材料,但是否具有... 相似文献
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农药缓释剂的研究—Ⅰ 总被引:3,自引:0,他引:3
本文首次将中西除虫菊酯用于控制释放,制备了以聚氨酯和聚脲为壁膜的微胶囊型缓释剂和以聚甲基丙烯酸酯为载体的整体型缓释剂(薄膜缓释剂)。分别用测残留量法和生物鉴定法测定了两种剂型缓释剂的农药释发速度,证明了它们的长效性和实用性。微胶囊型缓释剂的释放速度为常数,满足封闭—渗透释放机理;整体型缓释剂的农药释放速度在释放初期很快,然后变慢,满足扩散—溶质释放机理。 相似文献
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生物降解聚酯包埋利福平缓释微球的制备及释放行为 总被引:16,自引:0,他引:16
以生物可降解乙交酯和丙交酯的无规共聚物(PLGA)为载体,将抗结核病药利福平溶解于PLGA的有机溶液中,采用通常乳化-溶剂挥发方法制备了药物缓释微球.研究了影响微球制备的工艺条件.用电子显微镜观察了微球及降解后的表面形态,测定了微球粒径及载药量,评价了载药微球的体外释放行为.结果表明,以质量分数为1%的明胶为稳定剂,制备的微球形态完整,粒径范围为10~30μm,微球中利福平的平均质量分数为24.3%.体外释药时间可以通过高分子的降解速率来调控,本实验的释药时间可以在42~84d之间调控,药物缓释达到了理想的零级动力学释放.因此,利福平PLGA微球具有显著的长效、恒量药物缓释作用. 相似文献
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Min‐Shiun Chao 《中国化学会会志》2003,50(6):1131-1138
Ionic polyurethanes (PUs) were prepared from hydroxyl‐terminated polybutadiene (HTPB) and 4,4′‐dicyclohexylmethane diisocyanate (H12MDI) by a two‐stage method. The ionic group was introduced by adding 4,8‐diazaundecanediamide (L‐2,3,2) as the chain extender of which the tertiary amines and carbonyl groups were complexed with nickel ions. It was found that the binding of hard segments and the flexibility of soft segments had subtle effects on the gas permeability. The effects of hard segment content and the amount of nickel ion on the gas permeability and morphological properties were investigated. Fourier transform infrared (FTIR) spectroscopy was utilized to identify the segregation between hard and soft segments and structure change, which affect the transport properties. The hydrogen bonding index (HBI), frequency difference, and shift as a measure of the phase segregation and the average strength of the interpolymer hydrogen bonds were utilized to study the intermolecular interaction and transport property of the prepared PUs. The oxygen and nitrogen permeabilities of membranes were determined by using gas permeability analyzer. The results of FTIR, differential scanning calorimetry and thermogravimetric analysis measurements explain the complexation and, hence, the gas permeability. 相似文献
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《Arabian Journal of Chemistry》2020,13(1):393-403
In this study, novel smart drug release films were prepared by blending chitosan with polyethylene glycol methyl ether (PEGME), also named as methoxy polyethylene glycol (mPEG), for controlled drug release applications. The polymeric films were characterized by Fourier transform infra-red for functional groups analysis, scanning electron microscopy for morphology and X-ray photoelectron spectroscopy for chemical and surface analysis followed by mechanical and thermal analysis. The mechanical properties showed that with the addition of PEGME (40%), the tensile strength and elongation break were increased up to 34.14 MPa and 26.40%, respectively as compared to the controlled sample (without PEGME). The developed biodegradable films were tested for Metformin hydrogen chloride release ability at a particular rate in phosphate buffer saline solution at pH 7.4. The results showed that chitosan/PEGME blends could be employed for controlled drug release and other biomedical applications. 相似文献
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A new preconcentration method is presented for lead on TAN‐loaded polyurethane foam (PUF) and its measurement by differential pulse anodic stripping voltammetry (DPASV). The optimum sorption conditions of 1.29 × 10?5 M solution of Pb(II) ions on TAN‐loaded PUF were investigated. The maximum sorption was observed at pH 7 with 20 minutes equilibrated time on 7.25 mg mL?1 of TAN‐loaded foam. The kinetic study indicates that the overall sorption process was controlled by the intra‐particle diffusion process. The validity of Freundlich, Langmuir and Dubinin ‐ Radushkevich adsorption isotherms were tested. The Freundlich constants 1/n and KF are evaluated to be 0.45 ±0.04 and (1.03 +0.61) × 10?3 mol g?1, respectively. The monolayer sorption capacity and adsorption constant related to the Langmuir isotherm are (1.38 ± 0.08) × 10?5 mol g?1 and (1.46 ± 0.27) × 105 L mol?1, respectively. The mean free energy of Pb(II) ions sorption on‐TAN loaded PUF is 11.04 ± 0.28 kJ mol?1 indicating chemisorption phenomena. The effect of temperature on the sorption yields thermodynamics parameters of ΔH, ΔS and ΔG at 298 K that are 15.0 ± 1.4 kJ mol?1, 74 ±5 J mol?1 K?1 and ‐7.37 ± 0.28 kJ mol?1, respectively. The positive values of enthalpy (ΔH) and entropy (ΔS) indicate the endothermic sorption and stability of the sorbed complexes are entropy driven. However, the negative value of Gibb's free energy (ΔG) indicates the spontaneous nature of sorption. On the basis of these data, the sorption mechanism has been postulated. The effect of different foreign ions on the sorption and desorption studies were also carried out. The method was successfully applied for the determination of lead from different water samples at ng levels. 相似文献
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A series of poly (AM-co-HEA-co-AA) hydrogels have been synthesized and characterized by varying 2-hydroxy ethyl acrylate (HEA) content in the range of 0–16.22% in feed. The swelling ratio of resulting hydrogels was drastically decreased 10 times, i.e., from 101.12 to 9.23 in an almost linear fashion; but the dimensional stability of these hydrogels was increased significantly from 5 to 46 days with increasing HEA content. The hydrogels exhibited Smart nature in varying pH (2–10), temperature (15–65°C), ionic strength of NaCl solution (0.1M-1.5M), and different cation chloride salt solution having same ionic strength (0.1M). The swelling mechanism was shifted from non-Fickian to Fickian (at pH 2–7), super case to non-Fickian (at pH 10) with increasing HEA content. The controlled release of model drug (salicylic acid) from these hydrogels was investigated using early-time, late-time and Etters diffusion models and compared with the experimental data. It was observed that early model doesn't fit, but Etter and late-time model fitted excluding the initial phase. However, it was also observed that with increasing HEA content, the applicability of Etter's model improved, and for 16.22% HEA containing hydrogel Etters model was fitted in the full range, indicating that by varying hydrogel composition, the diffusion characteristics can be altered. 相似文献
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Multi-walled carbon nanotubes(MWCNTs) were grafted with poly(N-vinyl-2-pyrrolidone) and with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) at different compositions by using γ-rays technique as initiator. The MWCNTs, MWCNT-graft-PNVP, MWCNT-graft-PAMPS and MWCNTs-graft-P(NVP-co-AMPS) were characterized by Fourier transform infra red(FTIR) spectroscopy, X-ray diffraction(XRD), thermal gravimetric analysis(TGA), elemental analysis and high-resolution transmission electron microscopy(HR-TEM). The results indicated that the grafting processes of PNVP, PAMPS and P(NVP-co-AMPS) occurred on to the surfaces of MWCNTs without destroying the framework of MWCNTs. Tramadol hydrochloride(TH) was loaded as model drug and its release behavior was analyzed via various kinetic models. Release of the loaded TH was studied in simulated gastric fluid(SGF, p H = 1.2) and simulated intestinal fluid(SIF, p H = 7.4) at 37 °C. Controlled release of TH from grafted MWCNTs was investigated. The outcome results suggest that the grafted MWCNTs could be used as a promising matrix candidate for oral drug delivery system by harmonization between the composition and p H level of the simulated biological fluids. 相似文献
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Jaspreet S. Dhau Avtar Singh Amritpal Singh Balwinder S. Sooch 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):687-699
AbstractThe antioxidant activity of pyridylselenium compounds has been evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and nitric oxide (NO) scavenging methods. Pyridylselenium compounds have shown far superior (100–1000 times) antioxidant property than ebselen. The control release of bis(2-pyridyl) diselenide from poly(acrylamide) hydrogels has been studied in order to evaluate its release mechanism and diffusion coefficient. The later study also demonstrates that the pyridylselenium loading into the polymer matrix increases the magnitude and the rate of the radical scavenging activity of the poly(acrylamide) hydrogels. 相似文献
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The RAFT polymerization of methyl methacrylate (MMA) was carried out in the presence of 2-cyanoprop-2-yl 1-dithiophenanthrenate (CPDPA). The results exhibit controlled polymerization characters: well-controlled molecular weight with narrow polydispersity (minimal value: 1.04) molecular weight linearly increasing with conversion and first-order kinetics of polymerization. The resulting polymer can be used to synthesize methyl methacrylate-styrene copolymer with narrow polydispersity. The effect of molar ratio among MMA/CPDPA/AIBN on polymerization was investigated. 相似文献
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以光学活性的苯乙胺和吡啶-2-甲醛缩合而得到的Schif碱(PPEI)(PPEI=2-[[N-(1-phenylethyl)imino]methyl]pyridine或2-[[N-(1-苯乙基)亚胺]甲基]吡啶)为配体,进而与[Ir(COD)Cl]2(COD=1,5-环辛二烯)反应,合成了8个光学活性铱络合物,考察了它们在异丙醇存在下催化苯乙酮不对称氢转移反应的光学活性,发现[Ir(COD)(PPEI)I]具有较好的立体选择性.其光学产率最高可达35.7%e.e.. 相似文献
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将以三齿2,6 双(苯并咪唑)吡啶为配体的Cu(I)离子络合物用作A TRP引发体系的组分之一,并成功地实现了对烯类单体的自由基聚合.聚合过程具有明显的ATRP聚合特征.和几种具不同结构胺配体构成的Cu(I)络合物的聚合速度结果相比较,本工作的结果基本符合烷基胺≈吡啶>亚胺>芳基胺的序列关系. 相似文献