Dendrimers are globular, multi-functional, monodisperse macromolecules with perfect structure fidelity. Their architecture is composed of a series of branched polymeric arms, composed within “wedges”, that emanate from a central core. Their structure contains a high density of functional groups located at their periphery, referred to as the “outer shell”. Due to their globular structure, it is assumed that the relative “size” of a dendrimer does not fluctuate greatly between solvents. This may be due to the inability of the branched arms, or wedges, to significantly expand or collapse (comparative to analogous linear polymers) owing to steric barriers from branching, especially at higher generations. In contrast, it is expected that a linear polymer, of similar molecular weight to a dendrimer analog, would have a greater degree of size variation dependent on solvent-polymer interactions. This stems from its innate flexibility and greater conformational flexibility. For this investigation, analogous dendritic and linear bis-MPA polyesters as well as poly(caprolactone) (PCL) were analyzed using size-measuring techniques including gel permeation chromatography (GPC) and diffusion ordered spectroscopy-nuclear magnetic resonance (DOSY-¹H NMR).

中文翻译：

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使用DOSY-1H NMR的线性和树枝状bis-MPA类似物的溶液尺寸变化

树枝状大分子是具有完美结构保真度的球形，多功能，单分散大分子。它们的体系结构由一系列分支聚合物臂组成，这些分支臂由“楔子”组成，并从中央核心发出。它们的结构在其外围包含高密度的官能团，称为“外壳”。由于它们的球状结构，可以假定树枝状大分子的相对“大小”在溶剂之间波动不大。这可能是由于分支的空间屏障，特别是在更高的世代，由于分支的空间障碍，使得分支臂或楔形物不能显着膨胀或塌陷（与类似的线性聚合物相比）。相反，预计分子量与树枝状聚合物类似物相似的线性聚合物 取决于溶剂-聚合物相互作用，其尺寸变化的程度更大。这源于其固有的灵活性和更大的构象灵活性。在这项研究中，使用尺寸测量技术（包括凝胶渗透色谱法（GPC）和扩散有序光谱法-核磁共振法（DOSY-））对类似的树枝状和线性bis-MPA聚酯以及聚己内酯（PCL）进行了分析。¹ H NMR）。