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Sequence-Controlled α-Methylstyrene/Styrene Copolymers: Syntheses and Sequence Distribution Resolution
Macromolecules ( IF 5.1 ) Pub Date : 2020-09-10 , DOI: 10.1021/acs.macromol.0c01649 Arnaud Wolf 1, 2 , Jessica S. Desport 1 , Reiner Dieden 1 , Gilles Frache 1 , Marc Weydert 3 , Laurent Poorters 3 , Daniel F. Schmidt 1 , Pierre Verge 1
Macromolecules ( IF 5.1 ) Pub Date : 2020-09-10 , DOI: 10.1021/acs.macromol.0c01649 Arnaud Wolf 1, 2 , Jessica S. Desport 1 , Reiner Dieden 1 , Gilles Frache 1 , Marc Weydert 3 , Laurent Poorters 3 , Daniel F. Schmidt 1 , Pierre Verge 1
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The copolymerization of α-methylstyrene (MSt) and styrene (St) to form random and blocky copolymers is well-known. Strongly alternating copolymers of this type are rarely described, mainly because of difficulties linked to their characterization. Indeed, the chemical structures of St and MSt are sufficiently similar that quantitative determination of the sequence distribution is rather difficult. Here, we report a complementary pair of analytical methods based on nuclear magnetic resonance (NMR) and high-resolution mass spectrometry, respectively, to convincingly assess the structure of such copolymers. First, sequence-controlled poly(α-methylstyrene-alt-styrene) copolymers were obtained based on the single-unit addition principle, enabling unit-by-unit addition of the two monomers. The alternating character of these copolymers was then detected via carbon-13 (13C) NMR (13C NMR) and selective heteronuclear multiple bond correlation 2-dimensional NMR (SHMBC NMR) on aromatic quaternary carbons. Diad probabilities were quantified and used to calculate statistically derived quantities, reflecting the nature of the copolymer sequence distribution. In addition, HRMS and tandem mass spectrometry were performed to further confirm the alternating tendency of these copolymers, and they revealed a very narrow chemical composition distribution and fragmentation patterns specific to a primarily alternating structure.
中文翻译：
序列控制的α-甲基苯乙烯/苯乙烯共聚物：合成和序列分布分辨率
众所周知，α-甲基苯乙烯（MSt）和苯乙烯（St）的共聚形成无规和嵌段共聚物。很少描述这种类型的强交替共聚物，这主要是由于与其表征有关的困难。实际上，St和MSt的化学结构足够相似，因此很难确定序列分布。在这里，我们分别报告一对互补的基于核磁共振（NMR）和高分辨率质谱的分析方法，以令人信服地评估此类共聚物的结构。首先，序列控制下的聚（α-methylstyrene-中高音基于单单元加成原理获得-（苯乙烯）共聚物，从而能够将两个单体逐个单元地添加。然后，通过芳族季碳上的碳13（13 C）NMR（13 C NMR）和选择性杂核多键相关二维NMR（SHMBC NMR）检测这些共聚物的交替特征。Diad概率被量化并用于计算统计得出的数量，反映了共聚物序列分布的性质。此外，进行了HRMS和串联质谱分析以进一步证实这些共聚物的交替趋势，并且它们揭示了非常窄的化学组成分布和特定于主要交替结构的断裂模式。
更新日期：2020-09-22
中文翻译：
序列控制的α-甲基苯乙烯/苯乙烯共聚物：合成和序列分布分辨率
众所周知，α-甲基苯乙烯（MSt）和苯乙烯（St）的共聚形成无规和嵌段共聚物。很少描述这种类型的强交替共聚物，这主要是由于与其表征有关的困难。实际上，St和MSt的化学结构足够相似，因此很难确定序列分布。在这里，我们分别报告一对互补的基于核磁共振（NMR）和高分辨率质谱的分析方法，以令人信服地评估此类共聚物的结构。首先，序列控制下的聚（α-methylstyrene-中高音基于单单元加成原理获得-（苯乙烯）共聚物，从而能够将两个单体逐个单元地添加。然后，通过芳族季碳上的碳13（13 C）NMR（13 C NMR）和选择性杂核多键相关二维NMR（SHMBC NMR）检测这些共聚物的交替特征。Diad概率被量化并用于计算统计得出的数量，反映了共聚物序列分布的性质。此外，进行了HRMS和串联质谱分析以进一步证实这些共聚物的交替趋势，并且它们揭示了非常窄的化学组成分布和特定于主要交替结构的断裂模式。
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