Impact of Macromonomer Molar Mass and Feed Composition on Branch Distributions in Model Graft Copolymerizations.
Impact of Macromonomer Molar Mass and Feed Composition on Branch Distributions in Model Graft Copolymerizations.
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DOI：
10.1021/acsmacrolett.1c00640
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发表时间：
2021-12
影响因子：
5.8
通讯作者：
Aristotelis Zografos;Nathaniel A. Lynd;F. Bates;M. Hillmyer
中科院分区：
文献类型：
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作者：
Aristotelis Zografos;Nathaniel A. Lynd;F. Bates;M. Hillmyer
接枝聚合物可用于多种材料应用。了解接枝结构的变化，如接枝密度（z）、侧链聚合度（Nsc）和主链聚合度（Nbb）如何影响聚合物性能，对于准确调整材料性能至关重要。对于接枝贯穿共聚，Nsc和z的变化分别由大分子单体聚合度（NMM）和进料中大分子单体的初始分数（fMM 0）控制。我们发现，这些参数的变化可以影响共聚竞聚率，反过来，影响侧链分布沿着接枝聚合物主链。聚（（±）-丙交酯）大分子单体，NMM值低至约使用开环易位聚合（ROMP），在fMM 0值的范围（0.1 ≤ fMM 0 ≤ 0.8）内，将高达72的单体与小分子二甲酯双烯共聚单体共聚。使用1H核磁共振光谱测定了甲基丙烯酸酯转化率，并将数据与末端和非末端共聚模型拟合。从这项工作的结果提供了必要的信息操纵NSC和Z，同时保持合成控制接枝通过共聚的侧链分布。
Graft polymers are useful in a versatile range of material applications. Understanding how changes to the grafted architecture, such as the grafting density (z), the side-chain degree of polymerization (Nsc), and the backbone degree of polymerization (Nbb), affect polymer properties is critical for accurately tuning material performance. For graft-through copolymerizations, changes to Nsc and z are controlled by the macromonomer degree of polymerization (NMM) and the initial fraction of the macromonomer in the feed (fMM0), 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 NMM 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 fMM0 values (0.1 ≤ fMM0 ≤ 0.8) using ring-opening metathesis polymerization (ROMP). Monomer conversion was determined using 1H 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 Nsc and z while maintaining synthetic control over the side-chain distribution for graft-through copolymerizations.