Impact of Processing Effects on Surface Segregation of Bottlebrush Polymer Additives
Impact of Processing Effects on Surface Segregation of Bottlebrush Polymer Additives
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DOI：
10.1021/acs.macromol.2c01418
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发表时间：
2022-09-29
期刊：
影响因子：
5.5
通讯作者：
Verduzco，Rafael
中科院分区：
文献类型：
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作者：
Lee，Dongjoo;Charpota，Nilesh;Verduzco，Rafael
聚合物材料的表面性质决定了与周围环境的相互作用，并决定了各种应用相关的性质。最近的研究表明，瓶刷聚合物可用于改性聚合物的表面化学，因为当它们与线性聚合物共混时，它们自发地分离到界面，这在很大程度上是由瓶刷聚合物的独特结构引起的熵效应驱动的。然而，虽然先前的工作主要集中在平衡偏析分布，动力学和加工效果也可以驱动瓶刷添加剂的表面和界面。在聚合物和胶体的溶液浇铸共混物中，垂直分层由组分的相对Pe 'clet（Pe）数控制，即，溶剂蒸发和溶质扩散的相对速率。在此，我们研究了当与线性聚合物共混时，将瓶刷添加剂驱动到界面的加工效果。制备了瓶刷状聚苯乙烯（BBPS）和线性全氘代聚苯乙烯（dPS）的共混物，其中BBPS侧链长度固定为Nsc = 48，BBPS主链长度为Nb = 30-260，dPS链长为Nm = 40-548。通过改变溶剂和BBPS、dPS的粒径，改变BBPS、dPS的相对分子质量。与组分具有不同尺寸的其它二元共混物（例如，胶体/胶体、聚合物/胶体和聚合物/聚合物），我们发现相对Pennumber不能解释在这些瓶刷和线性聚合物共混物中观察到的偏析程度。对于一个固定的BBPS侧链长度，我们观察到较强的表面分离的瓶刷添加剂时，共混物是铸造使用较低沸点的溶剂和/或与较长的瓶刷聚合物的共混物。我们进一步表明，溶剂退火的膜可以增加富集瓶刷添加剂附近的表面。这项研究提供了深入了解的加工效果和共混物热力学的相互作用，管理瓶刷聚合物添加剂的表面偏析。
The surface properties of polymeric materials govern interactions with the surroundings and are responsible for various application-relevant properties. Recent studies have shown that bottlebrush polymers can be used to modify the surface chemistry of the polymers because they spontaneously segregate to the interfaces when they are blended with the linear polymers, driven in large part by entropic effects that arise from the unique architecture of bottlebrush polymers. However, while prior work has largely focused on equilibrium segregation profiles, kinetic and processing effects can also drive bottlebrush additives to surfaces and interfaces. In solution-cast blends of polymers and colloids, vertical stratification is controlled by the relative Péclet (Pe) numbers of the constituents, i.e., the relative rates of solvent evaporation and solute diffusion. Herein, we studied processing effects that drive bottlebrush additives to interfaces when blended with linear polymers. We prepared blends of bottlebrush polystyrene (BBPS) and linear perdeuterated polystyrene (dPS), where the BBPS side-chain length was fixed atNsc= 48, the BBPS backbone length ranged fromNb= 30–260, and the dPS chain length ranged fromNm= 40–548. The relativePenumbers of BBPS and dPS were varied by changing the solvent and sizes of BBPS and dPS. In contrast to other binary blends where the constituents have disparate sizes (e.g., colloid/colloid, polymer/colloid, and polymer/polymer), we found that the relativePenumber cannot account for the degree of segregation observed in these bottlebrush and linear polymer blends. For a fixed BBPS side-chain length, we observe stronger surface segregation of bottlebrush additives when the blend is cast using lower boiling point solvents and/or for blends with longer bottlebrush polymers. We further show that solvent annealing of the film can increase the enrichment of bottlebrush additives near surfaces. This study provides insight into the interplay of processing effects and blend thermodynamics that govern surface segregation of bottlebrush polymer additives.