Rui Jiayu, Cheng Siru, Ren He, Cui Sheng, Huang Jian
College of Materials Science and Engineering, Nanjing Tech University, No. 30 Puzhu Road (S), Nanjing 211816, China.
Polymers (Basel). 2024 May 24;16(11):1497. doi: 10.3390/polym16111497.
Plasma-initiated polymerization (PIP) is generally attributed to a radical process due to its inhibiting property. However, its unique polymerization behaviors like long-lived radical and solvent effect do not comply well with the traditional radical mechanism. Herein, the PIP of methyl methacrylate (MMA) was conducted in a high-voltage DC electric field to investigate the charged nature of its radicals. Consequently, the polymerization presented a preferential distribution of polymers at the anode but not the cathode, revealing the negatively charged nature of the growing radicals. An acceleration phenomenon, accompanied by the growth in molecular weights and the reduction in molecular weight distributions (), was observed at the voltages above 16 kV, suggesting the dissociation of ion pairs of growing radicals. The PIP yielded PMMA with analogous chemical and steric structures to those of PMMA from traditional radical initiation, whether in the presence or absence of the external electric field. This work offers new insights into the PIP of vinyl monomers, wherein a one-electron transfer reaction is inferred to be involved in the monomer activation.
由于其抑制特性，等离子体引发聚合（PIP）通常被认为是一个自由基过程。然而，其独特的聚合行为，如长寿命自由基和溶剂效应，与传统自由基机理并不完全相符。在此，在高压直流电场中进行甲基丙烯酸甲酯（MMA）的PIP，以研究其自由基的带电性质。结果，聚合反应在阳极而非阴极呈现出聚合物的优先分布，揭示了增长自由基带负电的性质。在高于16 kV的电压下观察到加速现象，同时分子量增加且分子量分布变窄，这表明增长自由基的离子对发生了解离。无论是否存在外部电场，PIP得到的聚甲基丙烯酸甲酯（PMMA）在化学结构和空间结构上与传统自由基引发得到的PMMA类似。这项工作为乙烯基单体的PIP提供了新的见解，其中推断单电子转移反应参与了单体活化。
