Characterization of polymer solutions containing a small amount of aggregates by static and dynamic light scattering
Characterization of polymer solutions containing a small amount of aggregates by static and dynamic light scattering
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DOI：
10.1021/ma0213899
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发表时间：
2003-03-25
期刊：
影响因子：
5.5
通讯作者：
Sato, T
中科院分区：
文献类型：
--
作者：
Kanao, M;Matsuda, Y;Sato, T
用静态和动态光散射法研究了聚异氰酸正己酯（PHIC）和无规聚苯乙烯在一定浓度下的聚集体溶液。它们的静态结构因子（k）和强度自相关函数g（（2））（t）分别表现出增强的小角散射和双峰弛豫。根据得到的（k）和g（（2））（t），静态结构因子（（S）over cap（k）和（S）over cap（slow）（k））和第一累积量（Gamma（fast）和Gamma（slow））的快模和慢模分量被估计为散射矢量k的大小的函数。如基于动态平均场理论的理论所证实的，如果溶液仅包含少量的扩散系数远小于非聚集组分的扩散系数的聚集体，则（S）/cap（slow）（k）和Gamma（fast）分别给出无聚集体溶液的渗透压缩性偏导数c/偏导数Pi和互扩散系数D-m，和（S）over cap（slow）（k）和Gamma（slow）分别为我们提供了聚集体的回转半径（1/2）（z，A）和流体动力学半径R-H，R-A，即使在有限的聚合物浓度下，也是很好的近似。事实上，偏导数/偏导数Pi和D-m得到的结果是有利的二元聚合物溶液的理论相比，没有聚集体。对于PHIC溶液，较低分子量样品的聚集体具有较大的（1/2）（z，A）和R-H，R-A，表明较低分子量PHIC的聚集体由大量的聚合物链组成。此外，（1/2）（z，A）与R-H，R-A的比值表明，高分子量的PHIC聚集体为刚性链状，而低分子量的PHIC聚集体为球状。
Aggregate-containing solutions of poly(n-hexyl isocyanate) (PHIC) and atactic polystyrene of finite concentrations were studied by static and dynamic light scattering. Their static structure factors, (k) and the intensity autocorrelation functions g((2))(t) exhibited the enhanced low-angle scattering and bimodal relaxation, respectively. From (k) and g((2))(t) obtained, the fast- and slow-mode components of the static structure factor ((S) over cap (k) and (S) over cap (slow)(k)) and of the first cumulant (Gamma(fast) and Gamma(slow)) were estimated as functions of the magnitude of the scattering vector k. As verified by a theory based on the dynamic mean-field theory, if the solution contains only a small amount of aggregates with diffusion coefficients much smaller than that of the nonaggregating component, (S) over cap (slow)(k) and Gamma(fast) give us the osmotic compressibility partial derivativec/partial derivativePi and mutual diffusion coefficient D-m of aggregate-free solutions, respectively, and (S) over cap (slow)(k) and Gamma(slow) provide us the radius of gyration (1/2)(z,A) and hydrodynamic radius R-H,R-A of aggregates, respectively, even at a finite polymer concentration, in a good approximation. In fact, the results of partial derivativec/partial derivativePi and D-m obtained were favorably compared with theories for binary polymer solutions without aggregates. For PHIC solutions, aggregates of lower molecular weight samples had larger (1/2)(z,A) and R-H,R-A, indicating that the aggregates of lower molecular weight PHIC consist of a larger number of polymer chains. Furthermore, the ratio of (1/2)(z,A) to R-H,R-A indicated that aggregates of higher-molecular-weight PHIC are rigid-chain-like but those of lower-molecular-weight PHIC are spherelike.