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41.
The aim of the present study was to investigate the effect of the presence of the water-soluble polymer polyvinylpyrrolidone (PVP) MW=24,000 g/mol, on the complexing of the anti-inflammatory drug nabumetone, with β-cyclodextrin (β-CD). The data show that the polymer interacts with the free nabumetone and with the nabumetone:β-CD inclusion complex, in both cases with a stoichiometry of 1:1. The interaction constants are 1.3×104 M−1 and 1.6×104 M−1, respectively.The presence of PVP, changes the drug:cyclodextrin interaction, a nabumetone:(β-CD)2:PVP complex being formed.In addition, the presence of PVP, produces a strong increase in the global binding constant, β2=(22.12±0.22)×106 M−2 at 1% PVP.In the ternary complex, the nabumetone is wrapped at both ends for the β-CD. In this complex the polymer seems to act as a bridge between both β-CD molecules that bind the nabumetone. 相似文献
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以不同平均分子质量的聚乙烯吡咯烷酮(PVP,通常用K值来表示PVP溶液相对粘度的特征值,粘度越大,PVP平均分子质量越大,平均分子质量为8000、40000、160000、360000的PVP分别标记为K17、K30、K60、K90)为表面活性剂,通过水热法合成了形貌和光学共振峰可控的银纳米结构.将反应体系加入到60 mL的不锈钢高压反应釜中,在一定的温度下加热数小时.我们在K17的水溶液中合成了尺寸均一的五重孪晶银纳米十面体.而在K30、K60和K90的乙二醇(EG)溶液中得到了纵横比随着PVP分子质量增大而增大的银纳米线.产物的形貌和微结构通过透射电镜(TEM)和场发射扫描电镜(FE-SEM)进行表征,表面等离子共振(SPR)吸收峰通过紫外-可见分光光度计进行测试,结果显示银纳米结构的表面等离子共振随着其形貌和尺寸的改变而发生变化. 相似文献
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Replacement of plasma by high molecular weight substances 总被引:1,自引:0,他引:1
In the course of the development work, natural and synthetic polymers were examined to see whether they were suitable for use as plasma substitutes. The criteria of a plasma substitute are discussed in this connection. The most important of the base substances used at present (dextran, modified gelatin, polyvinylpyrrolidone, and hydroxyethyl starch) are described, and a typical example of proven therapeutic value is discussed for each type. 相似文献
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采用一种简单和低成本的方法制备单分散SiO2包覆聚苯乙烯(PS)(PS/SiO2)核-壳型纳米复合微球.首先在聚乙烯吡咯烷酮(PVP)存在下制备了PS纳米微球,然后在NH4OH/乙醇溶液中通过溶胶-凝胶过程在PS微球表面包覆SiO2.PS纳米微球的制备在水介质中进行,无需使用共单体,使用的是常用的过硫酸钾自由基引发剂;包覆处理前不用进行溶剂交换或离心处理.研究了PVP,NH4OH和原硅酸乙酯(TEOS)的用量对PS/SiO2纳米复合微球尺寸和形态的影响.随着PVP用量增加,PS微球变小,因此得到较小的PS/SiO2纳米复合微球;NH4OH用量对SiO2包覆层的厚度没有影响,但对SiO2包覆层的表面形态有影响,随着NH4OH用量增加包覆层表面变得粗糙;随着TEOS溶液用量增加,生成的SiO2增加,其包覆层的厚度增加. 相似文献
45.
边长为微米级的银纳米片的简易合成与形成机理 总被引:2,自引:0,他引:2
用低温(60 ℃)溶剂热法, 以N,N-二甲基甲酰胺(DMF)为主还原剂和溶剂, 以聚乙烯吡咯烷酮(PVP)为辅助还原剂和晶面生长控制剂, 以硝酸银为前驱物, 大量制备了高纯度的、边长为微米级、宽厚比≥10的单晶银纳米片. 采用粉末X射线衍射(PXRD)、场发射扫描电镜(FE-SEM)、透射电子显微镜(TEM)等表征和分析了合成产物的成分、形貌和结构. 结果表明, 合成的银纳米片为面心立方单晶, 边长为1-4 μm, 厚度为50-100 nm. 考察了不同溶剂对银纳米结构的影响, 并提出了大尺寸的银纳米片的形成机理. 本文为调控单晶银纳米片的边长和宽厚比提供了一种新的可靠的动力学方法, 制备的长边长、大宽厚比的单晶银纳米片在聚合物基导电复合材料和电磁屏蔽材料方面有潜在的重要应用. 相似文献
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分散聚合法制备PVP微球的研究 总被引:1,自引:0,他引:1
以N-乙烯基吡咯烷酮(NVP)为初始单体,乙酸乙酯为分散介质,采用分散聚合法制备了分散性能良好、粒径为3~4μm的聚乙烯基吡咯烷酮(PVP)微球.考察了单体、分散剂及引发剂浓度对PVP微球的粒径、单体转化率及分子量的影响,并对PVP的结构和性能进行研究.结果表明,单体浓度增加,PVP微球粒径和分子量增大,单体转化率升高;分散剂浓度增加,PVP微球粒径变小,分子量增大,单体转化率升高;引发剂浓度增加,PVP微球粒径变大,分子量减小,单体转化率升高.与溶液聚合法相比,分散聚合法制备的PVP分子量较小且具有一定的结晶性. 相似文献
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聚酰亚胺/聚N-乙烯吡咯烷酮分子复合物的合成和表征 总被引:2,自引:0,他引:2
由原位缩聚制备了刚性高分子聚酰亚胺(PI)和柔性基体聚N-乙烯吡咯烷附(PVP)的分子复合物,并由实验证明了中间体聚酰胺酸(PA)和聚乙烯吡咯烷酮大分子之间存在的酸一碱相互作用.这种相互作用促进了混容性,使聚酰亚胺能以分子水平或接近分子水平分散在聚毗咯烷酮的基体之中.聚酰亚胺/聚N-乙烯吡咯烷团分子复合物的薄膜呈透明性,在整个组成范围内只有一个Tg,显示单相行为。当PI含量<20%时,SEM相片呈现均相形貌,看不到PI微晶.广角X-ray衍射图表明PI特征结晶峰消失,和无定形的PVP完全混容.当PI含量>40%,SEM显示有均匀分布的、棒状PI微晶存在.通过分子复合,即使PI含量为10%,聚N-乙烯吡咯烷酮不再溶于乙醇,耐热性也有提高. 相似文献
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Jian-hua Cao Bao-ku Zhu You-yi Xu 《高分子科学》2006,(2):205-211
Porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membranes were successfully prepared using dibutyl phthalate (DBP), polyvinylpyrrolidone (PVP-K30), polyethylene glycol 200 (PEG200) as templates. SEM was used to examine the morphology of the PVDF-HFP porous membranes. It was found that these membranes have an asymmetric structure and the blends of PVDF-HFP/DBP formed nanoporous membranes, whereas the blends of PVDF- HFP/PVP-K30 formed "sponge-like" and microporous membranes. Moreover, the average pore size and porosity was about 0.3 μm and 48.7%, respectively. The crystallinity, thermal stability and mechanical strength of membranes were characterized by XRD, DSC, TGA and stress-strain tests. The results showed that the membranes are a crystals with excellent thermal stability. It was an effective way to regulate pore size and morphology of the PVDF-HFP membranes. 相似文献
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