Progress in the research of high frequency and low dielectric materials containing fluorine

With the popularization of 4G communication technology and the continuous development of 5g communication technology, higher frequency communication technology (6G, 7g 10g) will be the development trend in the future, and the demand of high frequency and low dielectric materials is also increasing High frequency and low dielectric materials need to keep low dielectric constant and dielectric loss under high frequency conditions In addition, the materials themselves should also meet the application conditions of low water absorption, high heat resistance, excellent mechanical properties and processability Fluoropolymer has good low dielectric properties at high frequency, such as polytetrafluoroethylene (PTFE), but its processing performance is poor because of its molecular inertia, so it needs to be etched on its surface to increase the adhesion with copper foil, so it can be used in the next step Therefore, it is of great significance to develop the fluorine-containing low dielectric materials with easy processing and high performance Fang Qiang, Key Laboratory of Shanghai Institute of organic functional molecular synthesis and assembly, Chinese Academy of Sciences, has carried out systematic research in this field, developed heat crosslinkable fluorine-containing polymers by using the characteristics of heating into rings of trifluoroethylene ether, and obtained a series of research results in the near future By designing the strategy of large monomers with multi-functional degree (> 3), the chain growth of the polymer can be carried out in multiple directions, which effectively avoids the defect that it is difficult to form high molecular weight polymer with trifluoroethylene ether monomer This strategy can not only improve the processability of fluoropolymer, but also obtain good insulation, heat resistance and transparency In the synthesis of Trifluoroethyl ether, 2,6-dimethylpiperidine lithium (ltmp), which is strong in alkalinity and weak in nucleophilicity, was cleverly used in the elimination reaction of tetrafluoroethyl ether Tpm-tfve of tetra substituted trifluoroethylene ether was prepared in a simple and high yield The molecule has a tetrahedral framework, and a fluorine-containing polymer with microporous structure can be obtained by thermal crosslinking The polymer shows excellent dielectric properties Its dielectric constant is lower than 2.29 at 10 MHz, and its dielectric constant and dielectric loss are 2.36 and 1.29 × 10-3 at high frequency and 5 GHz, respectively It is superior to traditional commercial low dielectric materials (macrolecules 2016, 49, 7314) Fig 1 synthesis of tetrafunctional trifluoroethylene ether monomer and polymer Source: poss is a kind of nano material with unique cage structure, which is often introduced into polymer as additive to improve its mechanical and dielectric properties However, there are few studies on fluoride functionalization of POSS, mainly due to the lack of effective methods for direct fluorination After exploration, the group used highly efficient platinum catalyst hydrosilylation reaction, one-step reaction is to introduce fluorine-containing groups into poss, realizing the fluoroalkylation and functionalization of poss The new organic-inorganic hybrid materials and films obtained by thermal polymerization show high transparency and excellent dielectric properties (dielectric constant 2.51 and dielectric loss 3.1 × 10-3 at 5 GHz) Even in the humid environment, the hybrid material can maintain stable dielectric properties, creating conditions for its potential application in the field of high-frequency communication (ACS appl Mater Interfaces 2017, 9, 12782) Fig 2 preparation of organic-inorganic hybrid fluorine-containing poss Source: the research group of Shanghai organic Research Institute also found that Si OH group will be produced in hydrolysis and condensation of organosiloxane, and flexible si-ch2-ch2-segment will be produced in hydrosilylation reaction The existence of these groups and segments will have adverse effects on the dielectric properties and thermal stability of polysiloxane at high frequency In order to solve this problem, the research group through one-step piers rubinsztajn reaction, the basic industrial raw material TEOS was fluorine functionalized, in-situ formation of large fluorine-containing organosiloxane monomer thermal polymerization can form a transparent film, the film in 10 At ultra-high frequency of GHz, excellent properties such as dielectric constant of 2.50 and dielectric loss of 4.0 × 10-3 are shown, while the dielectric constant of ordinary non porous silica film and polysiloxane is usually greater than 3.0 (macrolecules 2017, 50, 9394) Fig 3 preparation of fluoroorganosiloxane macromonomer and polymer based on TEOS Source: the above research work of Shanghai organic Research Institute was mainly completed by Sun Jing, associate researcher, doctoral students Wang Jiajia and Luo Yijie, etc., and was supported by the Ministry of science and technology, the National Natural Science Foundation of China, and the strategic leading science and technology program (class B) of the Chinese Academy of Sciences Related thesis link: http://pubs.acs.org/doi/10.1021/acs.macromol.6b01678 http://pubs.acs.org/doi/10.1021/acsami.7b01415 http://pubs.acs.org/doi/10.1021/acs.macromol.7b02000 brief introduction of Fang Qiang researcher: source of Fang Qiang researcher: Shanghai organic Research Institute 1984, Department of chemistry, Guizhou University, Bachelor of science; 1991, Department of chemistry, Guizhou University, master of science; 1999, Department of polymer materials, Sichuan University, doctor of engineering; 2001-2004, Institute of resource chemistry, Tokyo University of technology, Japan, He is a special researcher of JSPS, and was selected into the "hundred talents plan" of Chinese Academy of Sciences in 2004 Now he is a researcher and doctoral supervisor of Polymer Research Office of Shanghai Institute of organic science, Chinese Academy of Sciences http://sourcedb.sioc.cas.cn/cn/expert/yjy/200906/t20090621_1750780.html