稀有事例探测是当前粒子物理、原子核物理等领域的重要科学前沿，对降低实验材料本底水平需求迫切。电子学基材是最靠近探测器晶体的关键器材之一，对探测器本底水平影响较大。此外液氮浸泡低温实验环境要求，电子学基材应具有较高层间粘合力和介电性能。聚四氟乙烯(PTFE)、聚全氟乙丙烯(FEP)是目前被广泛认可的低本底和高介电性能聚合物，但表面粘合力较差，通过离子注入法可有效提升聚合物表面粘合力且不影响基体良好的介电属性。因此，本文探索了具有交联或断链主导作用的离子注入聚合物对比行为，并开展聚合物表面粘合力机制研究，为实现稀有事例探测用高粘合力、耐低温和低本底电子学基材奠定重要基础。

首先，通过研究离子注入能量损失特性对聚合物表面改性机理及影响，基于SRIM程序模拟，本文设计了160 keV高电子阻止能力氮离子注入和8 keV高核阻止能力镍离子注入聚合物表面改性实验，实现了通过氮离子注入进行FEP和PTFE表面直接金属化的首次研究。同时，从离子注入后聚合物表面拓扑与化学变化共同作用机制的新角度，研究聚合物表面改性特性，该成果可作为改进聚合物力学和物化性能的重要理论基础。

其次，为提升聚合物表面粘合力，本文提出了聚合物表面粘合力分析的新方法，分析了具有交联或断链主导作用的离子注入聚合物对粘合力影响机理。自主研制的PTFE基电子学基材在液氮浸泡20天后的粘合力不低于0.67 N∙mm^-1，该成果高于目前可参考的国内工业标准水平(0.5 N∙mm^-1)。

此外，为实现低温下高介电性能，通过对分子结构调控宏观介电性能机制研究，利用离子束注入实现对聚合物近表层改性，改性后聚合物的介电性能未见明显下降。基于镍离子注入方法制备的电子学基材具有良好的介电性能，与国际领先稀有事例探测合作组用电子学基材相比，在-100 ℃低温下的介电损耗性能提高了近20倍。

最后，为实现低本底控制，基于本底来源分析开展低本底材料筛选工作，自主研制的新型电子学基材样品的²¹⁴Pb(²³⁸U)比活度小于95.2± 27.3 mBq∙kg^-1，该成果比国际领先稀有事例探测合作组用电子学基材的²¹⁴Pb(²³⁸U)比活度降低约一半，同时也是目前国内公开发表出版物中电子学基材最低本底水平。本文的研究成果可作为中国暗物质实验(CDEX)合作组未来吨量级稀有事例探测实验用电子学基材的优选制备方法。

Rare event detection is an important scientific frontier in particle Physics, nuclear Physics, and other fields, where the extremely low-background of materials is demanded. The background of detector crystal which is one of the key equipment closest to the detector crystal, could be easily affected by the electronic substrate. Furthermore, polymers of the electronic substrate are required with high interlayer adhesion and dielectric properties in the environment of liquid nitrogen immersion for the low-temperature experiments. Polytetrafluoroethylene (PTFE) and polytetrafluoroethylene propylene (FEP) are widely recognized with low-background and high dielectric properties, but their surface adhesion is poor. The polymers surface adhesion could be improved by Ion implantation without affecting the good dielectric properties of the matrix. Therefore, this thesis focuses on the comparative behavior of ion implanted polymers with cross-linking or chain breaking dominant effects, and analyses the surface adhesion mechanism of polymers, to lay an important foundation for achieving high adhesion, low-temperature resistance, and low-background electronic substrates for rare event detection.

Firstly, we studied the principle of surface modification by ion implantation and the influence of energy loss on the polymers. The 160 keV nitrogen ion implantation with high electron stopping power and 8 keV nickel ion implantation with high nuclear stopping power are designed on the surface modification of polymers. achieving the development of direct metallization study of FEP and PTFE surfaces through nitrogen ion implantation for the first time. Meanwhile, we analyzed the joint mechanism of polymer surface topology and chemical changes with ion implantation, from a new perspective. The related polymer surface properties can serve as an important theoretical basis for improving the mechanical and physicochemical properties of polymers.

Secondly, in order to improve the surface adhesion of polymers, we propose a new method for analyzing the surface adhesion of polymers, which provide direct insight into the influence of ion implantation on the polymer surface adhesion. The adhesion force of the self-developed PTFE based electronic substrate is with the value of 0.67 N∙mm^-1 after 20 days of immersion in liquid nitrogen, which is higher than the current domestic industrial standard that can be referenced (0.5 N∙mm^-1).

In addition, for the achievement of high dielectric properties at low-temperatures, the mechanism of molecular structure regulation with macro dielectric properties was studied. By modifying the near surface layer of the polymer using ion implanting, the dielectric properties of the modified polymer did not decline significantly. The prepared electronic substrate based on nickel ion implantation method has gotten the good dielectric properties. Furthermore, under low-temperature experimental conditions of -100 ℃, its dielectric loss performance is better than 20 times that of the electronic substrates used by leading international rare event experimental groups.

Finally, to control low-background, the low-background material screening was carried out based on the background source analysis. The specific activity of ²¹⁴Pb (²³⁸U) in the self-developed electronic substrate sample was less than 95.2 ± 27.3 mBq∙kg^-1, which is about half of the ²¹⁴Pb (²³⁸U) specific activity of the electronic substrate used by international leading rare event experimental groups. It is also the lowest background level of electronic substrate among the published publications in China. Furthermore, the research results have been adopted as the preferred electronic substrate preparation method for future ton level rare event detection experiments of CDEX.