Yang Xiaofan, Liu Jie, Bagnall Nicholas R, Heuts Johan P A, Worrell Brady, Waldron Christopher, Haddleton David M
Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K.
Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.
Macromolecules. 2025 Mar 6;58(6):3188-3198. doi: 10.1021/acs.macromol.5c00049. eCollection 2025 Mar 25.
Catalytic chain transfer polymerization (CCTP) of methacrylates using Co(II)/Co(III) catalysts has been established for over 30 years. These catalysts have been used in commercial products in diverse markets including automotive coatings, printing and dental composites. However, it has proved difficult routine and reliable tests of catalyst purity that indicate the activity and hence the amount of catalyst required to achieve a desired product. The catalysts are difficult to characterize due to being paramagnetic, sparingly soluble and highly symmetrical. This work set out to first determine the structure of "impurities" that might be present after synthesis or might form over time. Using this knowledge the work then used powder X-ray spectra and the deconvolution of obtained spectra to the known structures to obtain a measure of catalyst purity and activity. This was then correlated with the chain transfer constants from Mayo plots as a measure of activity. We discovered some new hitherto unknown cobalt structures and obtained structural data and developed a deconvolution algorithm that extracts the composition of the catalyst mixtures to give compositional data for 6 cobalt-containing compounds as well as starting materials and inorganic salts. Three of the cobalt species were shown to be active and thus the composition data was shown to be a measure of catalyst activity as tested against polymerization data. Catalyst samples from two laboratories were obtained which had been prepared at different times as well as a commercial sample. The powder X-ray method developed was subsequently used to validate the catalyst activity toward CCTP of methyl methacrylate. Thus, a relatively simple powder X-ray measurement on a catalyst sample can be used as a direct measure of activity and purity.
使用钴（II）/钴（III）催化剂进行甲基丙烯酸酯的催化链转移聚合（CCTP）已有30多年历史。这些催化剂已用于包括汽车涂料、印刷和牙科复合材料在内的多个不同市场的商业产品中。然而，事实证明，对催化剂纯度进行常规且可靠的测试很困难，而这种测试能表明催化剂的活性，进而表明获得所需产品所需的催化剂量。由于这些催化剂具有顺磁性、微溶性和高度对称性，因此难以对其进行表征。这项工作首先着手确定合成后可能存在或随时间形成的“杂质”的结构。利用这些知识，该工作随后使用粉末X射线光谱以及将所得光谱解卷积为已知结构，以获得催化剂纯度和活性的度量。然后将其与梅奥图中的链转移常数相关联，作为活性的度量。我们发现了一些迄今未知的新型钴结构，获得了结构数据，并开发了一种解卷积算法，该算法可提取催化剂混合物的组成，从而给出6种含钴化合物以及起始原料和无机盐的组成数据。其中三种钴物种显示具有活性，因此，经聚合数据测试，组成数据被证明是催化剂活性的一种度量。我们获得了来自两个实验室在不同时间制备的催化剂样品以及一个商业样品。随后，所开发的粉末X射线方法被用于验证催化剂对甲基丙烯酸甲酯CCTP的活性。因此，对催化剂样品进行相对简单的粉末X射线测量可直接用作活性和纯度的度量。
