Saccharin-pendant methacrylamide as a unique monomer in radical copolymerization: peculiar alternating copolymerization with styrene
Saccharin-pendant methacrylamide as a unique monomer in radical copolymerization: peculiar alternating copolymerization with styrene
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DOI：
10.1039/d0py01079k
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发表时间：
2020-10-28
影响因子：
4.6
通讯作者：
Ouchi, Makoto
中科院分区：
文献类型：
--
作者：
Kametani, Yuki;Ouchi, Makoto
在这篇文章中，我们报道了糖精悬挂的甲基丙烯酰胺(1)在自由基共聚合中的一种不寻常的反应活性。在一般自由基聚合条件下，由于N，N-二取代甲基丙烯酰胺本身反应性较低的单体具有较大的侧链，所以在一般自由基聚合条件下，大体积的亚乙烯分子不表现出均聚能力。然而，在存在苯乙烯的情况下，它以与苯乙烯相同的速度平稳地消耗。在单体竞聚率接近于零的情况下，1(M-1)和苯乙烯(M-2)的竞聚率分别为r(1)=0.040和r(2)=0.045，推测共聚单体对实现了交替共聚。由于1与其他共轭单体如甲基丙烯酸酯和丙烯酸酯的共聚没有进展，因此共聚是非常特殊的。密度泛函理论计算支持1的特殊共聚反应活性。该交替共聚物中1的侧链通过水解和甲基化反应生成甲酯，从而得到甲基丙烯酸甲酯和苯乙烯的交替共聚物，其交替序列用H-1和C-13核磁共振进行了表征。
In this article, we report an unusual reactivity of saccharin-pendant methacrylamide (1) in radical copolymerization. The bulky vinylidene molecule showed no homopolymerization ability under general radical polymerization conditions likely due to the bulky pendant for the inherently low reactivity monomer of N,N-disubstituted methacrylamide. However, in the presence of styrene, it was smoothly consumed at the same rate as styrene. Given the near-zero monomer reactivity ratios of the pair [r(1) = 0.040 and r(2) = 0.045 for 1(M-1) and styrene (M-2)], it was assumed that the comonomer pair afforded alternating copolymerization. The copolymerization was very specific to the combination since copolymerizations of 1 with other conjugated monomers such as methacrylate and acrylate did not progress. The peculiar copolymerization reactivity of 1 was supported by DFT calculations. The side chains of 1 in the alternating copolymer were converted into methyl ester via hydrolysis and methylation, and thus an alternating copolymer of methyl methacrylate and styrene was obtained, and the alternating sequence was characterized by H-1 and C-13 NMR.