Storable, Dual-Component Systems for Frontal Ring-Opening Metathesis Polymerization
Storable, Dual-Component Systems for Frontal Ring-Opening Metathesis Polymerization
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DOI：
10.1021/acs.macromol.2c00775
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发表时间：
2022-06
期刊：
影响因子：
5.5
通讯作者：
Benjamin A. Suslick;Aliza N. Yazdani;M. Cencer;J. E. Paul;Nil A. Parikh;Katherine J. Stawiasz;Isabel P.
中科院分区：
文献类型：
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作者：
Benjamin A. Suslick;Aliza N. Yazdani;M. Cencer;J. E. Paul;Nil A. Parikh;Katherine J. Stawiasz;Isabel P.
由GRUBS型Ru络合物催化的正面开环歧化聚合(FROMP)使高性能、高能效的结构塑料的合成成为可能。理想的催化剂经得起与树脂制备、储存和运输相关的较长时间。然而，目前的催化剂在环境条件下会在几小时到几天内引发过早聚合。在这项工作中，热潜伏的双-N-杂环卡宾络合物提供了非常坚固的树脂，这些树脂可以存活8周。当与CuIco试剂混合时，预催化剂活化使系统在热启动后具有快速反应能力。在这项研究中，40多个双组分配方成功地催化了双环戊二烯的FROMP。确定了每种成分的聚合工艺参数(前沿温度和速度)、树脂储存性和生成的聚合物性能(例如，Tg)。有趣的是，铜与Ru的比例显著影响了观测到的前沿速度和温度，以及聚合物的玻璃化转变温度；较慢、较冷的反应前沿来自于铜与Ru比例较大的配方。生成的聚合物具有较低的Tg值。对相关模型体系的机理分析表明，过量的铜试剂会降低活化和聚合速率。
Frontal ring-opening metathesis polymerization (FROMP) catalyzed by Grubbs-type Ru complexes enables new, rapid, and energy-efficient syntheses of high-performance, structural plastics. Ideal catalysts survive the extended time periods associated with resin preparation, storage, and transportation. Current catalysts, however, induce premature polymerization within hours to days under ambient conditions. In this work, a thermally latent bis-N-heterocyclic carbene complex provides exceedingly robust resins, which are viable for 8 weeks. When mixed with CuIcoreagents, precatalyst activation primes the system for rapid reactivity after thermal initiation. In this study, more than 40 dual-component formulations successfully catalyzed FROMP of dicyclopentadiene. The polymerization process parameters (front temperatures and velocities), resin storability, and resultant polymer properties (e.g.,Tg) were determined for each composition. Intriguingly, the Cu to Ru ratio dramatically impacts the observed frontal velocity and temperature, as well as the polymer glass-transition temperature; slower, colder reaction fronts result from formulations with large Cu to Ru ratios. The resultant polymers display lowerTgvalues. Mechanistic analysis of a related model system demonstrated that an excess Cu reagent decreases the activation and polymerization rates.