The information and communication technologies (ICT) have witnessed unprecedented developments for recent decades. Taking the wireless communication used for mobile telephony (MP) as an example, the first generation of mobile phone technologies was established in late 1980’s and were only available for few people and countries, but the individuals in contemporary society are strongly connected by the ubiquitous cellular communication so that there are more devices than inhabitants of the Earth at present. On the other hand, along with the popularization of WI-FI and other types of wireless data transfer, the emerging techniques in electromagnetic fields such as electromagnetic interference shielding, absorption, etc. has received increased research interests. Nowadays, we are in the beginning of next generation (5G) of cellular network, which is not only a new technology, but also bring deep impacts for various fields. Along with the deployment of increasing amount of high frequency powered based station and devices in 5G cellular network, various communication domains, ranging from virtual reality to autonomous vehicles to the industrial Internet, smart cities, the Internet of Things (IoT), as well as machines communicate with machines (M2M communication), have being inter-connected.

Considered that the 5G networks will work within the higher frequency parts of the electromagnetic spectrum, thus the previously used materials in the lower radio frequency are no longer appropriated for fabrication of devices for 5G communication. In this sense, the thriving developments of 5G indeed bring tremendous opportunities for the community of materials science and engineering. Polymeric materials and related composites are emerging as the important members in the race of 5G materials research and development, many new synthetic polymers, modification strategies, processing methods have been proposed and demonstrated good application promises for high speed wireless commutation. For this reason, we have prepared this special column entitled “5G” and invited several research groups working in the polymer science and engineering to summarize the recent research progresses of high performance polymers aiming for different subjections of 5G cellular communication. This special column includes four review articles and two research papers, the review articles mainly summarize the research progresses on low dielectric constant polymers for high speed communication network, fabrication strategies of polymer-based electromagnetic interference shielding materials, liquid crystal polyester (LCP) for 5G application, as well as, preparation and applications of low-dielectric constant poly aryl ether. While the two research articles focus on the synthesis and properties of phthalonitriles based thermosets and N-heterocycle-containing poly(phthalazinone ether)s dedicated for high frequency communication.

Since its commercialization in person communication in 2019, the development of 5G cellular communications has brought great impacts into the community of polymer science and engineering, various high performance polymers and composites, such as liquid crystal polymers, modified polyimide, polyarylene ethers, fluoropolymer, etc. have witnessed increasing developments and been successful applied in various high frequency devices. In the future, new polymers and novel strategies for polymer modification as well as processing are required to develop updated materials for next generation communication in terahertz frequency as well as space-earth integration network, and the experiences of research and development for 5G technology will definitely serve as valuable reference for materials design and devices fabrication for next generation cellular commutation. Finally, I hope this special column would provide useful guidelines for the community of polymer materials and engineering development for 5G communication.

High-performance polymer materials with low dielectric constant and low dielectric loss have been widely used in high-speed communication network. This review briefly introduces several common polymer materials, including polyimides, poly(benzoxazole)s, poly(aryl ether)s, poly(tetrafluoroethylene), and various porous polymers. Moreover, the preparation technology, various properties and applications of common low-dielectric polymers are discussed. Based on the desired properties and requirements for applications as low dielectric materials, the possibility of further development of porous polymer materials is discussed.

With the rise of the fifth-generation (5G) mobile communication, electromagnetic interference (EMI) and radiation become progressively serious toward electronic devices and human health, resulting in an increasing demand for EMI shielding materials. Polymer-based EMI shielding materials have drawn considerable attention in relevant industries and academia owing to their low density, easy processing, and superior flexibility. In this review, we systematically discuss the development of polymer-based shielding materials fabricated by using polymers as matrices and precursors. The architecture design of polymer composites is emphasized including homogenous structure, porous structure, laminated structure, and segregated structure. Specific attention is also given to the polymer derivatives from synthetic and natural polymers. Finally, we summarize the recent advancements and our guidelines for the development of polymer-based EMI shielding materials in the 5G era.

With the ever-growing demand for 5G networks and the promise of real-time, mission-critical applications, the advanced antennas with high-bandwidth and highly reliable connectivity are urgently needed. 5G networks primarily operate in two areas of spectrum below 6 GHz (known as sub 6) and millimeter wave, which are much higher than the working frequency of 4G cellular networks, thus the previously used materials and integration techniques need to be updated accordingly. In this sense, liquid crystal polyesters (LCP) have been considered as ideal high performance microwave/millimeter wave (mm-wave) substrate and packing materials due to their outstanding properties. More specifically, the LCP normally exhibit good thermal stability, low water absorption, stable dielectric constant and loss tangent in millimeter wave frequency range, which leads to the increasing research interests of LCP for 5G devices application in both academia and industrial fields. However, the review articles focusing on the chemistry and materials aspects of LCP intended for 5G application are unexpectedly limited. In this article, we will summarize the research progress of LCP materials used in 5G networks in the view of polymer science and engineering. More specifically, the polymerization, chemical structure, aggregated state, properties, modification and processing of typical LCP are reviewed, which would be useful for promoting practical application of the LCP in key devices of 5G networks.

With the rapid development of 5G technology, people have put forward many new requirements for low-dielectric materials. The newest version of 5G communication technology requires frequency ranges become higher. This means that the wavelength of waves used in the 5G communication technology become shorter. The shorter the wavelength of the electromagnetic wave is, the poorer the diffraction ability it has, and the stronger the attenuation that occurs during its propagation. The existing materials are far from meeting the new requirements of 5G technology. Therefore, the research of new low-dielectric materials has become a hot spot. This article summarizes the related researches on some new types of poly aryl ether materials with low dielectric constant and low dielectric loss to provide experience for follow-up work.

Modern microelectronics devices urgently request low dielectric constant materials with commendable mechanical properties. Novel fluorinated poly(aryl ether)s (FPPEs) were prepared by traditional polycondensation of 4-(4-Hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ), Bisphenol AF (BAF) and Decafluorobiphenyl (DFB) to study bulky phthalazinone effects on mechanical and dielectric behavior of polymers. After the introduction of phthalazinone moieties, FPPEs showed excellent solubility to readily solve in many organic solvents like NMP, DMAc, CHCl₃, and THF. Simultaneously, they exhibited relatively high glass transition temperatures (T_gs) from 180 °C to 294 °C, increasing with the content of phthalazinone groups. The FPPEs still possessed excellent thermal stability with decomposition temperature up to 514 °C and char yield at 800 °C as high as 56% under nitrogen atmosphere. FPPE films showed good mechanical strength with tensile stress higher than 68MPa and modulus surpassing 10.8MPa, also increasing with phthalazinone concentration. The dielectric property of FPPEs was investigated with impedance analyzer. FPPE8020 and FPPE 6040 showed dielectric constant from 3.10-3.30 and dielectric loss of 0.005-0.008 under a large frequency range of 0.02-60GHz. The phthalazinone moieties mainly contributed to the decrease of dielectric constant. The results evidently suggest FPPEs as commendable candidate for those high-tech electronic applications.