Molecular characterization of a hyperbranched polyester. II. Small-angle neutron scattering
Molecular characterization of a hyperbranched polyester. II. Small-angle neutron scattering
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超支化聚酯的分子表征。
DOI：
10.1002/polb.10464
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
S. King
中科院分区：
文献类型：
--
作者：
E. D. Luca;R. Richards;I. Grillo;S. King
用小角中子散射研究了超支化聚酯在氘代四氢呋喃溶液中的一系列组分。使用2至5%w/v的聚合物浓度，并且从数据的Zimm图获得分子参数。第二维里系数是积极的，这些值被证实了稀释溶液光散射的一小部分，氘代四氢呋喃作为溶剂。的小角中子散射数据表现出的一般功能预测的粒子散射功能的非随机支化聚合物，但一个精确的拟合的理论方程的数据不能得到的超支化聚合物的所有馏分，特别是那些高分子量。被排除的数量效应被认为是造成这种分歧的一个可能原因。从氘代四氢呋喃溶液中的聚合物的微分散射截面的散射矢量依赖性得到的分形维数为2.5，这与重均分子量的回转半径的依赖性的标度指数一致。超支化聚合物的含氢四氢呋喃溶液表现出负的第二维里系数，这归因于同位素对聚合物-溶剂组合的热力学性质的影响。© 2003 Wiley Periodicals，Inc.聚合物科学杂志B部分：聚合物物理41：1352-1361，2003
A series of fractions of a hyperbranched polyester in deutero tetrahydrofuran solution were investigated by small-angle neutron scattering. Concentrations of polymer from 2 to 5% w/v were used, and the molecular parameters were obtained from Zimm plots of the data. Second virial coefficients were positive, and these values were confirmed by dilute-solution light scattering on a small number of fractions with deutero tetrahydrofuran as a solvent. The small-angle neutron scattering data exhibited the general features predicted for the particle scattering functions of nonrandomly branched polymers, but an exact fit of the theoretical equation to the data could not be obtained for all fractions of the hyperbranched polymer, particularly those of high molecular weight. Excluded volume effects were cited as a possible cause for this disagreement. A fractal dimension of ∼2.5 was obtained from the scattering vector dependence of the differential scattering cross section of the polymer in deutero tetrahydrofuran solution, which agreed with the scaling exponent for the dependence of the radius of gyration on weight-average molecular weight. Hydrogenous tetrahydrofuran solutions of the hyperbranched polymer exhibited negative second virial coefficients that were attributed to isotopic influences on the thermodynamic properties of the polymer–solvent combination. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1352–1361, 2003