An associating polymer generally contains a small fraction of strongly interacting groups that can form stable aggregates. In this study, a novel soluble polyimide (PI) (6FDA-TFDB) sample with high molecular weight is synthesized; it contains a large fraction of relatively weak interacting groups. Investigation on the solution property and scaling law relationship between η₀-η_s and volume fraction shows that this sample exhibits the behavior of associating polymer; this behavior fits the theory of unrenormalized sticky Rouse model and sticky reptation model in a broad volume fraction region, and the scaling exponents in different volume fraction ranges and the critical volume fractions are determined. Moreover, when the volume fraction is above ϕ* (overlap volume fraction), abnormal shear thinning phenomenon occurs. Oscillation frequency experiment for concentrated polyimide solutions demonstrates that the polyimide solution tends to become a gel above the critical volume fraction due to numerous weak dipole-dipole and π-π interactions. In the UV–Vis spectra, absorption peak shows a red shift with volume fraction, demonstrating that aggregates form in concentrated polyimide solution. Synchrotron radiation small-angle X-ray scattering (SAXS) experiment reveals the appearance of domain, which comes from the aggregates of PI segments. Finally, combined with the quantum chemical calculation, one model based on relatively weak interaction (i.e., dipole-dipole and π-π interactions) from chemical units of polyimides is proposed to explain the associating behavior of high molecular weight polyimide in solution and the shear thinning phenomenon. This study broadens the range of associating polymers.

缔合聚合物通常包含一小部分可以形成稳定聚集体的强相互作用基团。在这项研究中，合成了一种新型的高分子量可溶性聚酰亚胺（PI）（6FDA-TFDB）样品。它包含大部分相对较弱的相互作用基团。对溶液性质的调查和标度律关系之间η ₀ - η_小号和体积分数表明，该样品显示出缔合聚合物的行为; 这种行为符合在较宽的体积分数区域中的未归一化粘性Rouse模型和粘性复制模型的理论，并确定了不同体积分数范围和临界体积分数的缩放指数。此外，当体积分数大于ϕ*（重叠体积分数），发生异常剪切稀化现象。浓缩聚酰亚胺溶液的振荡频率实验表明，由于许多弱的偶极-偶极和π-π相互作用，聚酰亚胺溶液往往会在临界体积分数以上变成凝胶。在UV-Vis光谱中，吸收峰显示出随体积分数的红移，表明在浓缩的聚酰亚胺溶液中形成聚集体。同步辐射小角度X射线散射（SAXS）实验揭示了域的出现，该域来自PI段的聚集体。最后，结合量子化学计算，建立了一个基于相对弱相互作用的模型（即，提出了聚酰亚胺化学单元的偶极-偶极和π-π相互作用）来解释高分子量聚酰亚胺在溶液中的缔合行为和剪切稀化现象。这项研究拓宽了缔合聚合物的范围。