Hydration and dehydration play crucial roles in hydrophobic effects (HEs) and are yet to be understood. Poly(γ-benzyl-L-glutamate) (PBLG) homopolymers in THF/water with various water contents were investigated. We discovered that PBLG was hydrated at low water contents and adopted a helical conformation. The chain became dehydrated with increasing water content, which converted the PBLG₁₀₀ helix to a PPII-helix. The variation in the conformation resulted in an alteration of the self-assembled morphologies from fibers to particles. For PBLG₁₂ with a shorter chain, the chain underwent an α-to-β transition in the conformation due to dehydration as the water content increased, and correspondingly the morphologies varied from tapes to helical ribbons, and eventually to toroids at a higher water content. We also observed that this α-to-β transition is accompanied by an increase in intensity of the fluorescence, which is attributed to the through-space-conjugation of tightly packed phenyl groups within the β-sheet. The discovered effect of hydration and dehydration on the PBLG chain conformation, self-assembling behavior and optical function is essential for the innovation of polypeptide materials and understanding of water-mediated biological systems.

中文翻译：

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水化和脱水对PBLG构象、组装行为和光致发光的影响

水合和脱水在疏水效应 (HE) 中起着至关重要的作用，但仍有待理解。研究了具有不同水含量的 THF/水中的聚 (γ-苄基-L-谷氨酸) (PBLG) 均聚物。我们发现 PBLG 在低含水量下水合并采用螺旋构象。该链随着水含量的增加而脱水，这将 PBLG ₁₀₀螺旋转变为 PPII 螺旋。构象的变化导致自组装形态从纤维到颗粒的改变。对于 PBLG ₁₂对于较短的链，随着含水量的增加，由于脱水，该链在构象中经历了α-β转变，相应地，形态从带状变为螺旋带状，并最终在较高含水量下变为环形。我们还观察到这种 α 到 β 的转变伴随着荧光强度的增加，这归因于 β 折叠内紧密堆积的苯基的空间共轭。发现的水合和脱水对 PBLG 链构象、自组装行为和光学功能的影响对于多肽材料的创新和对水介导的生物系统的理解至关重要。