Studies of the Excluded-Volume Effects and Chain Conformations of Oligomers and Polymers in Dilute Solutions.

在这项工作中，我们研究了排除体积效应对低聚物和聚合物中具有固定立体化学组成的无规聚苯乙烯（外消旋二分体的分数f_r=0.59）、f_r=0.79的无规聚（甲基丙烯酸甲酯）和具有固定链端结构的pol13EA\：异丁烯稀溶液性能的影响。结果表明：1)对于旋转-半径膨胀因子alpha_s，准双参数格式是有效的。也就是说，alpha_s可以仅表示为Yamakawa-Stockmayr-Shimada理论中定义的缩放的排除体积参数*的函数，该理论在螺旋虫状链（HW）的基础上考虑了排除体积和链刚度的影响。由于链的刚度，传统的双参数理论对alpha_s不成立。链刚度的影响在M - >0 ^6.2时仍然很大（约13ea \: en），准双参数格式对α - > < α - >时也是有效的。即使对于M > 10^6，链刚度对α _<eta>的影响仍然很大。如果在特性粘度[eta]_<(] SY中没有观察到排水效应，则在13ea \: α _<eta>中不会出现排水效应。水平分割的圆。[)> at THETA.3)出现在第二维里系数A_2中的互穿函数psi并非仅是alpha_s的函数，这表明对于psi，无论是传统的-格式还是准双参数格式都是无效的。psi分别取决于M和on13EA\：由于链条刚度的排除体积强度。考虑链刚度对A_2.4的影响的Yamakawa理论可以半定量地解释psi的实验结果。对于小M，链端对A_2的影响在THETA和良好溶剂中都是显著的。即使相对较大的M达到约10^5，这种效应也不能忽视。所观察到的A_2对M的依赖关系可以用考虑了A_2对M的影响的Yamakawa13EA理论来定量表达。少

In this work, we have studied the excluded-volume effects on dilute solution properties of atactic polystirene with fixed stereochemical composition (the fraction of racemic diads f_r=0.59), atactic poly(methyl methacrylate) with f_r=0.79, and pol13EA\ : yisobutylene with fixed structure of chain ends over a wide range of molecular weight M from oligomers and polymers. The obtained findings are summarized as follows :1)A quasi-two-parameter scheme is valid for the gyration-radius expansion factor alpha_s. That is, alpha_s may be expressed as a function only of the scaled excluded-volume parameter * defined in the Yamakawa-Stockmayr-Shimada theory that takes a13EA\ : ccount of the effects of excluded-volume and chain stiffness on the basis of the helical wormlike (HW) chain. The conventional two-parameter theory does not hold for alpha_s because of chain stiffness. The effect of chain stiffness remains large ev13EA\ : en for M > 10^6.2)The quasi-two-parameter scheme is also valid for th … More e viscosity-radius expansion factor alpha_<eta> as in the case of alpha_s. The effect of chain stiffness on alpha_<eta> also remains large even for M > 10^6. The draining effect does not appear in13EA\ : alpha_<eta>, if it is not observed in the intrinsic viscosity [eta]_<(〕SY.horizontally divided circle.〔)> at THETA.3)The interpenetration function psi appearing in the second virial coefficient A_2 is not a function only of alpha_s, indicating that neither the conventional- nor the quasi-two-parameter scheme is valid for psi. psi depends separately on M and on13EA\ : the excluded-volume strength because of chain stiffness. The experimental results for psi are semi-quantitatively explained by the Yamakawa theory that takes account of the effect of chain stiffness on A_2.4)For small M, the effect of chain ends on A_2 is significant in both THETA and good solvents. The effect cannot be neglected even for relatively large M up to ca. 10^5. The observed M dependence of A_2 is quantitatively expressed by the Yamakawa13EA\ : theory that takes account of that effect on A_2. Less