Zhang Fan, Lei Heng, Guo Feng, Hu Jiangtao, Liu Haiming, Wang Qing, Liu Weihua, Xing Zhe, Wu Guozhong
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, No. 2019 Jialuo Road, Jiading District, Shanghai 201800, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Polymers (Basel). 2025 Jun 24;17(13):1751. doi: 10.3390/polym17131751.
Cyclic Olefin Copolymer (COC) is an amorphous thermoplastic polymer synthesized through the catalytic copolymerization of α-olefin and cyclic olefin. When used in pre-filled syringes and pharmaceutical packaging, COCs require radiation sterilization. The radiation sterilization alters the microstructure of COC, which ultimately affects its performance and biosafety. In this study, to investigate the effects of γ-radiation on COC microstructures, ethylene-norbornene copolymers with various compositions, representative of COC, are studied by nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. During irradiation, the COC containing 35 mol% norbornene produced free radicals that triggered migration and reaction processes, leading to the formation of entanglements within flexible chain segments. This, in turn, affected nearby ring structures with high steric hindrance, resulting in a 9.2% decrease in internal particle size and an increase in particle spacing. Conversely, when the norbornene content in COC was increased to 57 mol%, the internal particle size increased by 17.9%, while the particle spacing decreased.
环烯烃共聚物（COC）是一种通过α-烯烃与环烯烃催化共聚合成的无定形热塑性聚合物。当用于预填充注射器和药品包装时，COC需要进行辐射灭菌。辐射灭菌会改变COC的微观结构，最终影响其性能和生物安全性。在本研究中，为了研究γ辐射对COC微观结构的影响，采用核磁共振（NMR）和小角X射线散射（SAXS）技术对具有不同组成、代表COC的乙烯-降冰片烯共聚物进行了研究。在辐照过程中，含有35 mol%降冰片烯的COC产生自由基，引发迁移和反应过程，导致柔性链段内形成缠结。这反过来又影响了附近具有高空间位阻的环结构，导致内部粒径减小9.2%，颗粒间距增大。相反，当COC中的降冰片烯含量增加到57 mol%时，内部粒径增加了17.9%，而颗粒间距减小。
