In contrast to covalent polymer brushes, directional supramolecular forces such as hydrogen bonds or π–π-interactions govern the formation of supramolecular polymer bottlebrushes (SPBs) in a self-assembly process starting from single polymer building units. In an attempt to broaden our understanding of these processes and the required supramolecular forces, we here investigated the benzenetrispeptide (BTP) motif to self-assemble polyethylene oxide (PEO) chains into SPBs in water. For this purpose, we synthesized a library of BTP-PEO conjugates, in which we varied the amino acid unit (alanine vs. leucine vs. phenylalanine), the hydrophobic spacer (C₆ vs. C₁₂), and the steric hindrance imposed by PEO (2 vs. 5 vs. 10 kg mol⁻¹, one vs. three polymer chains). In particular, the type of amino acid was hypothesized to have a crucial influence on the final morphology. A detailed characterization of the respective solutions revealed that for the C₆ spacer and one PEO_2k chain, only phenylalanine containing core units formed the desirable SPBs, while in the other cases only spherical micelles (leucine) or barely any aggregation (alanine) was observed. In contrast, the more hydrophobic C₁₂ spacer resulted in an exclusive formation of SPBs, whereas the choice of the amino acid moiety had a minor influence on the observed morphology. Increasing the steric hindrance finally resulted in a transition from cylindrical toward spherical micelles. The broad structural variety offered by the choice of amino acids not only allows for an excellent control of the solution morphologies but also the potential integration of functional units to the core.

中文翻译：

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氨基酸对苯三肽在超分子聚合物毛笔中水自组装的影响

与共价聚合物刷相反，方向​​性超分子力（例如氢键或π-π相互作用）控制着从单个聚合物构建单元开始的自组装过程中超分子聚合物刷（SPB）的形成。为了拓宽我们对这些过程和所需的超分子力的理解，我们在这里研究了苯三肽（BTP）基序，以将聚环氧乙烷（PEO）链自组装成水中的SPB。为此，我们合成了一个BTP-PEO共轭物文库，其中我们改变了氨基酸单位（丙氨酸对亮氨酸对苯丙氨酸），疏水间隔子（C ₆ 对C ₁₂）和由位阻所造成的位阻PEO（2 vs.5与10千克摩尔^-1，一个与三种聚合物链）。特别地，假设氨基酸的类型对最终形态具有关键影响。各个溶液的详细表征表明，对于C ₆间隔基和一条PEO _2k链，仅包含苯丙氨酸的核心单元形成了所需的SPB，而在其他情况下，仅观察到球形胶束（亮氨酸）或几乎没有聚集（丙氨酸）。 。相反，疏水性更强的C ₁₂间隔基导致SPB的排他性形成，而氨基酸部分的选择对观察到的形态影响很小。空间位阻的增加最终导致从圆柱状胶束向球形胶束的转变。氨基酸的选择提供了广泛的结构多样性，不仅可以很好地控制溶液的形态，还可以将功能单元潜在地整合到核心上。