Block ratio and block sequence of polypeptide influenced the self-assembly of copolymer significantly. Tuning self-assembly to form various nanostructures with different properties through molecular design was a rather feasible strategy. Triblock copolymers based on poly(l-alanine) (PA), poly(l-valine) (PV) and poly (ethylene glycol) (PEG) with various block ratio and block sequence were synthesized. The number of amino acid residues was kept at 10. The sol-gel transition behavior, self-assemble nanostructure, secondary structure of the copolymers in aqueous solution were investigated to reveal that PA block between PEG and PV segment interfered the β-sheet structure, resulting in the reduced or increased sol-gel transition temperature or precipitation depended on the block ratio of PA and PV. Shorter PA or PV block displayed more significant influence on sol-gel transition. Interestingly, PV block between PEG and PA segment induced the formation of more stable β-sheet stacking structures, leading to sol-gel transition at higher temperature. PEG dehydration and the enhancement of ordered structure with temperature rising caused the sol-gel transition of these copolymers. We concluded herein that disordered structure in co-polypeptide can enhance thermo-sensitivity.

多肽的嵌段比和嵌段序列对共聚物的自组装有显着影响。通过分子设计调整自组装形成具有不同性质的各种纳米结构是一种相当可行的策略。基于聚 ( l-丙氨酸) (PA)、聚 ( l-丙氨酸) 的三嵌段共聚物合成了不同嵌段比和嵌段序列的-缬氨酸(PV)和聚(乙二醇)(PEG)。氨基酸残基数保持在10个。研究了共聚物在水溶液中的溶胶-凝胶转变行为、自组装纳米结构、二级结构，揭示了PEG和PV片段之间的PA嵌段干扰了β-折叠结构，导致溶胶-凝胶转变温度降低或升高或沉淀取决于 PA 和 PV 的嵌段比。较短的 PA 或 PV 块对溶胶-凝胶转变的影响更大。有趣的是，PEG和PA段之间的PV阻断诱导形成更稳定的β-折叠堆叠结构，导致在更高温度下的溶胶-凝胶转变。PEG脱水和随着温度升高有序结构的增强导致这些共聚物的溶胶-凝胶转变。我们在此得出结论，共多肽中的无序结构可以增强热敏感性。