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排序方式: 共有92条查询结果,搜索用时 46 毫秒
1.
Alaa?S.?Abd-El-AzizEmail author Sarrah?A.?Carruthers Pedro?M.?Aguiar Scott?Kroeker 《Journal of Inorganic and Organometallic Polymers and Materials》2005,15(3):349-359
A number of hyperbranched polymers containing cyclopentadienyliron moieties were prepared using the A2+B3 method. The A2 compounds used were common diols, dithiols or dichloroarenecomplexes. B3 compounds included either prepared star-shaped molecules or a purchased triol. The effect of the reaction conditions on the
properties of the products was probed. Analysis of the prepared polymers was conducted using 1H and 13C NMR, viscometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Viscometry values were generally
found to be low, in the range of 0.175–0.300 dl/g. TGA showed losses starting at approximately 230°C and ending at 280°C,
corresponding to the decomposition of the cyclopentadienyliron moiety. Degradation of the polyether backbone was found to
occur starting at 390–567°C. Glass transition temperatures were found to be between 60 and 134°C, whereas melting temperatures
ranged from 155 to 190°C. 相似文献
2.
以2,4-甲苯二异氰酸酯(2,4-TDI)、季戊四醇、丙烯酸羟乙酯(HEA)为原料合成了星型结构的丙烯酸酯,该树脂稳定性好,力学性能优良,原料易得且价格低廉,用途广,利于工业规模生产。文中探讨了反应温度、反应时间和单体投料比对星型结构四官能团丙烯酸酯光固化树脂合成的影响。结果表明,最佳的合成条件为:第一步合成温度控制在45~50℃,反应时间80 min;第二步合成温度控制在65~70℃,反应时间60min;季戊四醇、2,4-甲苯二异氰酸酯和丙烯酸羟乙酯的物质的量比为1∶4∶4.08。实验表明该合成方法简单,反应温和,易控制,生产工艺清洁。 相似文献
3.
4.
以α-溴代异丁酸叔丁酯(BIBTB)为引发剂,CuBr/Bpy为催化体系引发甲基丙烯酸甲酯(MMA)聚合得到大分子引发剂PMMA-Br,利用电荷转移络合物效应以PMMA-Br引发支化单体二苯甲烷双马来酰亚胺(BMI)和苯乙烯就地优先生成双官能团大分子引发剂再继续引发苯乙烯得异臂星状聚合物。采用1H-NMR、GPC、MALLS、FT-IR和DSC等方法对聚合反应过程、聚合物及其水解产物进行分析测试。研究结果表明:利用电荷转移络合物效应就地生成双官能团大分子引发剂合成异臂星状聚合物是可行的。 相似文献
5.
采用活性阴离子聚合技术,以BuLi为引发剂,DVB为偶联剂,在环己烷体系中合成了星形多官能团大分子PS-b-PI.然后以此星形大分子作为接枝剂,通过阳离子聚合,合成了一种在每个星形大分子的臂上接枝几个聚异丁烯的新型支化聚合物,并对其进行了GPC、1H-NMR、FT-IR等分析表征,讨论了不同的加料顺序对其的影响,1H-NMR结果表明其接枝效率达80%左右. 相似文献
6.
《国际聚合物材料杂志》2012,61(5):246-255
Star-shaped temperature- and pH-sensitive poly (N-isopropylacryamide-co-itaconic acid) copolymer is synthesized by atom transfer radical polymerization (ATRP) using 1,2,3,4,6-penta-O-Isobutyrylbromide-α-D-glucose as 5-Arm ATRP Initiator. For ATRP of itaconic acid (IA), carboxylic groups of IA are protected via silylation by hexamethyldisilazane (HMDS) using Fe3O4 as a magnetic catalyst. The polymerization is carried out in 2-propanol/toluene 50:50 (v/v) mixed solvent at 90°C. Structure of copolymers is studied with FT-IR, 1H NMR, glass transition temperature (Tg), and scanning electron microscopy (SEM). Results of temperature, pH, and percentage variation on polymer structure and the effects on lower critical solution temperature (LCST), which is investigated with potentiometery and conductometry, show that LCST of copolymer is around body temperature and demonstrate the ability of this polymer in the design of controlled drug delivery systems. According to the obtained results from naltrexone release, the investigated star-shaped copolymer may have potential applications in the controlled release of drugs. 相似文献
7.
研究了分别使用大尺寸金纳米壳与星型金纳米颗粒修饰极大角倾斜光纤光栅(ExTFG)的局域表面等离子体共振(LSPR)传感器,实验对比了这两种ExTFG-LSPR传感器的折射率传感特性。实验结果表明:修饰星型金纳米颗粒的ExTFG传感器,其TM、TE模的基于波长变化的折射率灵敏度分别提升约15.52和12.8nm/RIU,但共振吸收效应不明显;而修饰大尺寸金纳米壳的ExTFG传感器,在大尺寸金纳米壳的LSPR作用下,其TM、TE模的基于波长变化的折射率灵敏度分别提升约31.1和26.99nm/RIU,同时,TM与TE模在C-L波段表现出强烈的共振吸收,基于归一化强度变化的折射率灵敏度分别约为185.18%/RIU和251.83%/RIU。 相似文献
8.
9.
Reza Teimuri Mofrad Roghieh Alizadeh Soghra Ramazani Ali Reza Vaez 《Polymer-Plastics Technology and Engineering》2018,57(9):893-902
A combination of ring-opening polymerization and atom-transfer radical polymerization was used to synthesize a four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate). The structure of obtained copolymer was determined by Fourier transform infrared, 1H and 13C NMR spectroscopies. The uniform electroactive nanofibers consisting blend of four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate) copolymer and polyaniline were produced using electrospinning technique. The electroactivity of prepared nanofibers was investigated using cyclic voltammetry measurement. The morphologies of electrospun nanofibers produced from four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate) and their blends with polyaniline were investigated by the scanning electron microscopy. The presence of polyaniline resulted in significant decrease of sticking fibers. 相似文献
10.
Self-assembled behavior of rod-terminally tethered three-armed star-shaped coil block copolymer melts was studied by applying self-consistent-field lattice techniques in three-dimensional (3D) space. Similar to rod-coil diblock copolymers, five morphologies were observed, i.e., lamellar, perforated lamellar, gyroidlike, cylindrical and sphericallike structures, while the distribution of the morphologies in the phase diagram was dramatically changed with respect to that of rod-coil diblock copolymers. The perforated lamella was replaced by the cylinder when frod = 0.45, and the lamella was replaced by the perforated lamella when frod = 0.5 when the arms A1 and A2 had an equal length and the volume fraction of A3 arm was low enough. Simulations were also performed when the arms A1 and A2 had unequal lengths. These results demonstrate that simple branching in the coil induces interesting microphase transitions. 相似文献