【摘要】：具有高介電常數(shù)、低介電損耗以及高儲能密度的聚合物納米復合電介質(zhì)材料在現(xiàn)代電子和電氣設(shè)備中有廣泛的應(yīng)用前景,研究和開發(fā)具有高性能的聚合物納米復合電介質(zhì)材料在推動國民經(jīng)濟發(fā)展和提升國家防衛(wèi)能力方面具有極其重要的意義。盡管前人為提升聚合物納米復合電介質(zhì)材料的綜合性能做出了很多貢獻和努力,但依然還有不少問題亟待解決,如納米填料的分散性問題、納米填料與聚合物基體之間的界面問題、以及納米填料的高填充量問題等。為了解決這些問題,本文探索了一系列簡單、快速、高效可控的方法,對納米填料的表面進行功能化改性,通過設(shè)計合成不同的界面結(jié)構(gòu),系統(tǒng)地研究了界面結(jié)構(gòu)對聚合物納米復合電介質(zhì)材料性能的影響,并在此基礎(chǔ)上,成功地制備了具有優(yōu)越的介電性能的聚合物納米復合電介質(zhì)材料。首先,為了提高納米顆粒的分散性以及納米顆粒與聚合物基體的界面相容性,我們分別采用“Grafting from”和“Grafting to”的策略,以鈦酸鋇(Ba TiO3,BT)納米顆粒為核,通過原位引發(fā)的可逆加成斷裂鏈轉(zhuǎn)移(RAFT)聚合和“巰基-乙烯基”(“Thiol-Ene”)點擊化學反應(yīng),設(shè)計合成了一系列具有核-殼結(jié)構(gòu)的Polymer@BT聚合物納米復合電介質(zhì)材料。在這一類材料中,絕緣的聚合物殼不僅可以充當隔離層來防止BT納米顆粒的團聚,而且還可直接充當聚合物基體。納米填料與聚合物基體之間通過共價鍵相連,因此聚合物納米復合材料中的界面結(jié)構(gòu)很緊密。在這個過程中,我們采用FT-IR、1H NMR、TGA、TEM、動態(tài)光散射等測試手段對納米顆粒的表面改性進行了詳細表征,證明了核-殼結(jié)構(gòu)的Polymer@BT納米顆粒的成功制備。并且,還通過調(diào)節(jié)單體配比或接枝聚合物鏈的分子量,對聚合物納米復合材料的組成或接枝密度進行調(diào)控,系統(tǒng)地研究了界面結(jié)構(gòu)對聚合物納米復合材料介電性能的影響。其次,為了進一步提升介電性能,我們開發(fā)了一種新的策略,以改善高介電常數(shù)的納米填料(BT)和鐵電聚合物基體聚偏氟乙烯-六氟丙烯[P(VDF-HFP)]之間的界面。首先,通過表面引發(fā)的RAFT聚合,在BT顆粒表面引發(fā)兩種類型的氟代丙烯酸酯單體聚合,合成了具有核-殼結(jié)構(gòu)的Fluoro-polymer@BT納米顆粒,使顆粒表面的殼層聚合物具有不同的厚度或不同的分子結(jié)構(gòu)。接著,通過溶液共混和熱壓成型工藝制備了P(VDF-HFP)/Fluoro-polymer@BT納米復合材料。相應(yīng)的納米復合材料的介電性能和能量存儲能力分別由寬頻介電譜儀和鐵電儀進行了測試。結(jié)果表明,所制備的納米復合材料成功地實現(xiàn)了高的儲能密度和低的介電損耗。而且,這類P(VDF-HFP)納米復合材料的介電性能和儲能密度可以通過調(diào)節(jié)Fluoro-polymer@BT納米顆粒表面含氟聚合物殼的結(jié)構(gòu)和/或厚度進行調(diào)控。第三,為了降低聚合物納米復合材料的介電損耗,提高其擊穿強度和儲能密度,我們設(shè)計合成了具有草莓狀核-殼結(jié)構(gòu)的BT-PDA-Ag納米顆粒,并以P(VDF-HFP)聚合物作為基體,通過溶液共混和熱壓成型工藝制備了聚合物納米復合電介質(zhì)材料。利用多巴胺的自聚合特性和還原性,在BT納米顆粒表面包覆一層聚多巴胺(PDA),并通過原位還原將Ag納米顆粒嵌入到殼層的PDA聚合物中。利用Ag納米顆粒的庫侖阻塞效應(yīng),成功地抑制了聚合物納米復合材料內(nèi)部的泄漏電流、降低了介電損耗、提高了擊穿強度和儲能密度。最后,為了降低填料含量,制備可以應(yīng)用于小型化、輕量化以及柔韌化電子電氣設(shè)備的聚合物納米復合電介質(zhì)材料,我們開發(fā)了一種精確可控和環(huán)境友好的方式來制備含氟聚合物功能化改性的石墨烯(PF-PDA-RGO),用于制備柔性的鐵電聚合物基納米復合電介質(zhì)材料。與未改性的RGO相比,我們所制備的PF-PDA-RGO在P(VDF-HFP)聚合物基體中具有良好的分散性,相應(yīng)的聚合物納米復合材料具有緊密的界面結(jié)構(gòu),以及較低的逾滲閾值(=1.06 v%)。因此,我們所制備的P(VDF-HFP)/PF-PDA-RGO納米復合材料在較低的填料含量時即可顯示出較高的介電常數(shù),同時還可以保持相對較低的介電損耗和優(yōu)良的柔韌性。這為制備高性能的柔性納米電解質(zhì)材料提供了一條有效的途徑。
[Abstract]:the polymer nano composite dielectric material with high dielectric constant, low dielectric loss and high energy storage density has wide application prospect in modern electronic and electrical equipment, The research and development of polymer nano-composite dielectric materials with high performance are of great significance in the development of national economy and the improvement of national defense ability. Although the predecessors have made many contributions and efforts to improve the comprehensive performance of the polymer nano composite dielectric material, there are still many problems to be solved, such as the dispersion problem of the nano-filler, the interface problem between the nano-filler and the polymer matrix, And the like. In order to solve these problems, a series of simple, rapid and high-efficiency and controllable methods are explored, the surface of the nano-filler is functionalized and modified, and the influence of the interface structure on the properties of the polymer nano-composite dielectric material is systematically studied through the design of different interface structures. And on the basis of that, the polymer nano composite dielectric material with excellent dielectric property is successfully prepared. First, in order to improve the dispersibility of the nanoparticles and the interface compatibility of the nanoparticles with the polymer matrix, we adopt the "Grafting from" and the "Grafting to" strategy, respectively, and the nano-particles of the titanium dioxide (Ba _ 3, BT) are the core, A series of Polymer@BT-polymer nanocomposite dielectric materials with a core-shell structure were designed by the in-situ reversible addition-fragmentation chain transfer (RAFT) polymerization and the "Kentucky-vinyl" ("Pol-Ene")-click chemical reaction. In this class of materials, the insulating polymer shell can serve not only as an isolation layer, to prevent the agglomeration of the BT nanoparticles, but also to act as a polymer matrix. The nano-filler is connected with the polymer matrix through a covalent bond, so that the interface structure in the polymer nano composite material is very close. In this process, the surface modification of the nanoparticles was characterized by FT-IR, 1H NMR, TGA, TEM, dynamic light scattering and the like, and the successful preparation of the Polymer@BT nanoparticles of the core-shell structure was proved. And the influence of the interface structure on the dielectric property of the polymer nano composite material is systematically studied by adjusting the monomer ratio or the molecular weight of the graft polymer chain, controlling the composition or the grafting density of the polymer nano composite material. Second, in order to further improve the dielectric properties, a new strategy was developed to improve the interface between the high dielectric constant nanofiller (BT) and the ferroelectric polymer matrix polyvinylidene fluoride[P (VDF-HFP)]. First, through the surface-induced RAFT polymerization, two types of fluoroacrylate monomers are polymerized on the surface of the BT particles, and the Fluoro-polymer@BT nanoparticles with the core-shell structure are synthesized, so that the shell-layer polymers on the surface of the particles have different thicknesses or different molecular structures. Then, P (VDF-HFP)/ Fluoro-polymer@BT nanocomposite was prepared by solution blending and hot pressing. The dielectric properties and energy storage capacity of the corresponding nanocomposites were tested by a wide-band dielectric spectrometer and an iron electrometer, respectively. The results show that the prepared nanocomposite successfully achieves high energy storage density and low dielectric loss. Furthermore, the dielectric properties and the energy storage density of such P (VDF-HFP) nanocomposite materials can be regulated by adjusting the structure and/ or thickness of the fluoropolymer shell on the surface of the Fluoro-polymer@BT nanoparticles. thirdly, in order to reduce the dielectric loss of the polymer nano composite material, improve the breakdown strength and the energy storage density, the BT-PDA-Ag nanoparticles with the strawberry-shaped core-shell structure are designed, and the P (VDF-HFP) polymer is used as a matrix, And the polymer nano composite dielectric material is prepared through a solution blending and hot pressing forming process. A layer of polydopamine (PDA) is coated on the surface of the BT nanoparticle using the self-polymerization characteristic and the reducibility of the dopamine, and the Ag nanoparticles are embedded in the PDA polymer of the shell layer by in-situ reduction. By using the coulomb blocking effect of the Ag nanoparticles, the leakage current in the polymer nanocomposite is successfully suppressed, the dielectric loss is reduced, and the breakdown strength and the energy storage density are improved. Finally, in order to reduce the filler content, a polymer nanocomposite dielectric material that can be applied to a miniaturized, lightweight, and flexible electronic electrical device can be prepared, We developed a highly controlled and environmentally friendly way to prepare a fluoropolymer-functionalized modified graphene (PF-PDA-RGO) for the preparation of a flexible ferroelectric polymer-based nanocomposite dielectric material. The PF-PDA-RGO prepared as compared to the unmodified RGO has good dispersibility in the P (VDF-HFP) polymer matrix, and the corresponding polymer nanocomposite has a compact interface structure and a lower percolation threshold (= 1.06 v%). Therefore, the P (VDF-HFP)/ PF-PDA-RGO nanocomposite prepared by our method can exhibit a high dielectric constant at a lower filler content while still maintaining a relatively low dielectric loss and excellent flexibility. This provides an effective way for the preparation of high-performance, flexible, nano-electrolyte materials.
【學位授予單位】：上海交通大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB383.1;TB33
，

本文編號：2463768