光诱导无金属原子转移自由基引发体系在氟聚合物改性中的应用

Novel poly(vinylidene fluoride) (PVDF) based dielectric materials with tunable ferroelectric properties show potential applications as sensors and high energy density capacitors. Chemically modifying commercial poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-CTFE)) via substitution or grafting reaction using C-Cl bond as active site has been found to be a low cost and facile strategy for the synthesis of the objective materials. In these reactions, metal compounds such as copper complexes in atom transfer radical polymerization (ATRP) have to be utilized as catalysts in most of cases. However, the residual metal ions in the resultant polymers could hardly be completely removed. That would badly harm the electric properties under elevated electric field and limits the application of the resultant polymers in many fields. In an effort to avoid the metal ion residue in the resultant polymers from metal compounds based reagents or catalysts, in this proposal, a photo-induced metal-free atom transfer radical initiation system would be designed for the modification of P(VDF-CTFE) for the first time. The regulation of photo-initiating system on the structure of resultant polymers would be firstly clarified by studying the grafting or hydrogenation reactions with different kinds of photo-catalysts under various reaction conditions, and carefully investigating the chemical structure of modified polymers. The new strategy may provide a new route for the synthesis and development of novel PVDF based ferroelectric materials with high purity. Secondly, a detection method of trace copper ion would be established in order to determine the content of copper ion in modified copolymers synthesized based on Cu-mediated ATRP reaction system. Thirdly, by comprehensively evaluating the electric performance of modified polymers prepared with photo-induced initiation system and traditional ATRP catalysts, the relationship between copper ion content and the electrical performance of polymers would be disclosed. That may help to give a deep understanding of the influence mechanism of ions onto the electrical properties of these ferroelectric materials, which is rather important for their performance improvement and application under high electric field.

对聚（偏氟乙烯-三氟氯乙烯）（P(VDF-CTFE)）进行化学改性可以开发出具有可调铁电特性的新型PVDF基电介质材料，在传感及高储能等领域具有重要应用。已有改性方法主要以C-Cl键为活性点通过取代、接枝等反应来实现。产物中来自于引发体系的金属离子（如铜离子）残留难以根除，严重制约着该类材料的电性能提升及应用。本项目拟将光诱导无金属原子转移自由基引发体系用于P(VDF-CTFE)的化学改性，以制备出无金属离子残留的PVDF基改性聚合物，通过改性新方法的建立和对改性产物化学结构的系统研究，明确光引发体系对聚合物结构的调控机制。针对采用铜盐络合物引发体系制备的改性共聚物，建立聚合物中微量铜离子的定量检测方法，通过对不同方法制备的改性聚合物电性能的对比分析，阐明铜离子对聚合物电性能影响的定量关系，为高性能PVDF基铁电材料的研发提供新方法及理论指导。

对聚(偏氟乙烯-三氟氯乙烯) (P(VDF-CTFE))进行化学改性可以开发出具有可调铁电特性的新型PVDF基电介质材料，在传感及高储能等领域具有重要应用。已有改性方法主要以C-Cl键为活性点通过取代、接枝等反应来实现。产物中来自于引发体系的金属离子(如铜离子)残留难以根除，严重制约着该类材料的电性能提升及应用。本项目拟将光诱导无金属原子转移自由基引发体系用于P(VDF-CTFE)的化学改性，以制备出无金属离子残留的PVDF基改性聚合物。首先，采用光诱导的无金属参与的原子转移自由基聚合法在P(VDF-CTFE)侧链成功接枝上聚甲基丙烯酸甲酯链段。动力学结果表明接枝聚合反应符合一级动力学关系。通过与传统ATRP催化体系相比，光催化体系得到接枝聚合物在低频和高温下的介电损耗明显降低、漏导损耗降低、击穿电场大幅提高。其次，开发了含氢硅烷催化体系氢化P(VDF-CTFE)制备含有TrFE共聚物的新途径，该氢化体系具有实验条件安全温和、无金属离子参与、并且化学组成可控等优点。再次，采用光诱导的metal-free ATRP引发体系催化P(VDF-CTFE)大分子引发剂，使其形成大分子自由基，利用其向溶剂或链转移剂的链转移反应同样可以实现氢化。光催化氢化反应具有易操作、廉价、可控等特点，得到聚合物的化学组成可通过改变链转移试剂的加入量和反应时间来进行调控。