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

本文研究了在较宽的分子量范围内，排除体积效应对具有固定立体化学组成（外消旋二元组分数fr =0.59）的无规聚苯乙烯、fr =0.79的无规聚甲基丙烯酸甲酯和具有固定链端结构的聚13乙基异丁烯稀溶液性质的影响。结果表明：1）准双参数格式对回转半径展开因子α_s是有效的。也就是说，α_s可以表示为Yamakawa-Stockmayr-Shimada理论中定义的比例排除体积参数的函数，该理论在螺旋蠕虫链的基础上考虑了排除体积和链刚度的影响。由于链刚度的影响，传统的双参数理论对α_s不成立。当M > 10时，链刚度的影响仍然很大，ev 13 EA：en = 6.2）准双参数格式对M > 10时也是有效的。 关于我们 e粘度-半径膨胀因子α_<eta>as（在α_s的情况下）。即使<eta>M &gt; 10 ^6，链刚度对α的影响也很大。在13 EA α中不出现排液效应，<eta>但在特性粘数[η] SY中没有观察到排液效应。出现在第二维里系数A_2中的互穿函数psi不是仅α_s的函数，这表明传统的和准双参数方案对psi都是无效的。psi分别取决于M和13 EA：由于链刚度而产生的排除体积强度。考虑了链刚度对A_2的影响，用Yamakawa理论半定量地解释了psi的实验结果。4）对于小分子量，链端对A_2的影响在THETA和良溶剂中都是显著的。即使M较大，其影响也不能忽略。10^5 A_2对M的依赖性可用考虑M对A_2影响的Yamakawa 13 EA理论定量表示。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