Molecular weight and dispersity (Ð) influence physical and rheological properties of polymers, which are of significant importance in polymer processing technologies. However, these parameters provide only partial information about the precise composition of polymers, which is reflected by the shape and symmetry of molecular weight distribution (MWD). In this work, the effect of MWD symmetry on thermal and rheological properties of polymers with identical molecular weights and Ð is demonstrated. Remarkably, when the MWD is skewed to higher molecular weight, a higher glass transition temperature (T_g), increased stiffness, increased thermal stability, and higher apparent viscosities are observed. These observed differences are attributed to the chain length composition of the polymers, easily controlled by the synthetic strategy. This work demonstrates a versatile approach to engineer the properties of polymers using controlled synthesis to skew the shape of MWD.

中文翻译：

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操纵分子量分布形状作为控制加工参数的新策略

分子量和分散度（Ð）影响聚合物的物理和流变性，这在聚合物加工技术中具有重要意义。但是，这些参数仅提供有关聚合物精确组成的部分信息，这由分子量分布（MWD）的形状和对称性反映出来。在这项工作中，证明了MWD对称性对具有相同分子量和Ð的聚合物的热和流变性质的影响。值得注意的是，当MWD偏向更高的分子量时，更高的玻璃化转变温度（T _g），增加的刚度，增加的热稳定性和更高的表观粘度。这些观察到的差异归因于聚合物的链长组成，很容易通过合成策略进行控制。这项工作展示了一种通用的方法，可通过受控合成来改变MWD的形状，从而对聚合物的性能进行工程设计。