Li Yen-Cheng, Chen Chun-Yu, Chang Ying-Xun, Chuang Pei-Ying, Chen Jean-Hong, Chen Hsin-Lung, Hsu Chain-Shu, Ivanov Viktor A, Khalatur Pavel G, Chen Show-An
Department of Applied Chemistry, National Chiao Tung University, Hsin-Chu 30050, Taiwan.
Langmuir. 2009 Apr 21;25(8):4668-77. doi: 10.1021/la803339f.
The conformational structure and the interchain aggregation behavior of a semirigid conjugated polymer bearing a decyl side chain, poly(2,3-diphenyl-5-decyl-1,4-phenylenevinylene) (DP10-PPV), in solutions with chloroform and toluene have been investigated by means of small-angle neutron scattering (SANS), static light scattering (SLS) and dynamic light scattering (DLS). The radius of gyration, persistence length, and the second virial coefficient of the polymer in dilute solution as determined by SLS were higher in chloroform than in toluene; consequently, the polymer assumed a more extended wormlike chain conformation in the former. The difference in the strength of interaction in the two solvents gave rise to contrasting aggregation behavior of the polymer in the semidilute regime. While only a minor fraction of the polymer underwent segmental association in chloroform, a considerable fraction of it formed clusters (microgels) with several micrometers in size in toluene. These clusters were further found to consist of sheetlike nanodomains. Compared with the DP-PPV bearing a shorter hexyl side chain, DP6-PPV, the aggregates of DP10-PPV in toluene were weaker as they could be easily disrupted by moderate heating. This was attributed to a lack of strong pi-pi interaction between the DP10-PPV segments due to the greater steric hindrance imposed by the longer decyl side chains.
通过小角中子散射（SANS）、静态光散射（SLS）和动态光散射（DLS）研究了带有癸基侧链的半刚性共轭聚合物聚（2,3 - 二苯基 - 5 - 癸基 - 1,4 - 亚苯基亚乙烯基）（DP10 - PPV）在氯仿和甲苯溶液中的构象结构和链间聚集行为。由SLS测定的聚合物在稀溶液中的回转半径、持久长度和第二维里系数在氯仿中比在甲苯中更高；因此，聚合物在前者中呈现出更伸展的蠕虫状链构象。两种溶剂中相互作用强度的差异导致聚合物在半稀溶液状态下呈现出截然不同的聚集行为。在氯仿中只有一小部分聚合物发生链段缔合，而在甲苯中相当一部分聚合物形成了尺寸为几微米的聚集体（微凝胶）。进一步发现这些聚集体由片状纳米域组成。与带有较短己基侧链的DP - PPV（DP6 - PPV）相比，DP10 - PPV在甲苯中的聚集体较弱，因为它们可以通过适度加热轻易地被破坏。这归因于较长的癸基侧链所带来的更大空间位阻，导致DP10 - PPV链段之间缺乏强π - π相互作用。
