Zografos Aristotelis, Lynd Nathaniel A, Bates Frank S, Hillmyer Marc A
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455-0132, United States.
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712-1589, United States.
ACS Macro Lett. 2021 Dec 21;10(12):1622-1628. doi: 10.1021/acsmacrolett.1c00640. Epub 2021 Dec 3.
Graft polymers are useful in a versatile range of material applications. Understanding how changes to the grafted architecture, such as the grafting density (), the side-chain degree of polymerization (), and the backbone degree of polymerization (), affect polymer properties is critical for accurately tuning material performance. For graft-through copolymerizations, changes to and are controlled by the macromonomer degree of polymerization () and the initial fraction of the macromonomer in the feed (), respectively. We show that changes to these parameters can influence the copolymerization reactivity ratios and, in turn, impact the side-chain distribution along a graft polymer backbone. Poly((±)-lactide) macromonomers with values as low as ca. 1 and as high as 72 were copolymerized with a small-molecule dimethyl ester norbornene comonomer over a range of values (0.1 ≤ ≤ 0.8) using ring-opening metathesis polymerization (ROMP). Monomer conversion was determined using H nuclear magnetic resonance spectroscopy, and the data were fit with terminal and nonterminal copolymerization models. The results from this work provide essential information for manipulating and while maintaining synthetic control over the side-chain distribution for graft-through copolymerizations.
接枝聚合物在多种材料应用中都很有用。了解接枝结构的变化，如接枝密度（）、侧链聚合度（）和主链聚合度（）如何影响聚合物性能，对于精确调整材料性能至关重要。对于接枝共聚反应，和的变化分别由大分子单体聚合度（）和进料中大分子单体的初始分数（）控制。我们表明，这些参数的变化会影响共聚反应的竞聚率，进而影响沿接枝聚合物主链的侧链分布。使用开环易位聚合（ROMP），将值低至约1且高至72的聚（（±）-丙交酯）大分子单体与小分子二甲基酯降冰片烯共聚单体在一系列值（0.1≤≤0.8）范围内进行共聚。使用氢核磁共振光谱法测定单体转化率，并将数据与端基和非端基共聚模型进行拟合。这项工作的结果为在保持对接枝共聚反应侧链分布的合成控制的同时，操纵和提供了重要信息。
