Branched thermotropic liquid crystal polymer with favourable processability and dielectric properties

Wang, Shengyu; Ma, Sainan; Li, Na; Jie, Suyun; Luo, Yingwu; Gao, Xiang

doi:10.1016/j.eurpolymj.2023.112302

Cited by 11 publications

(7 citation statements)

References 41 publications

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“…Regarding a subject that is especially important in the case of LCERs, Carfagna and his team, the great pioneers in this field, found that both the level of curing and the physical properties of the hardener are strongly affected by the nature of the hardener [ 10 ], so it is extremely important to investigate a broad selection of curing agents and compare their effects on the network. The importance of this matter has become even greater since LCERs became the foundation for manufacturing high-end materials for 5G antennas [ 11 ], tunable actuators with reprocessibility [ 12 ], microrobotics and micromachinery [ 13 ], highly conductive polymers [ 14 ], vitrimers [ 15 ], optical devices [ 16 , 17 ], and high-impact-strength polymers [ 18 ], as well as for providing a property-enhancing factor in powder coatings [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Nonterminal Liquid Crystalline Epoxy Resin Structure and Curing Agents on the Glass Transition of Polymer Networks

Kisiel,

Mossety-Leszczak

2024

Polymers

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Modern science and technology demand a low glass transition temperature, yet one tailored to specific thermoset needs and specific to individual hardener applications. Two novel, nonterminal liquid crystalline epoxy resins (LCER) were synthesised, with their structures characterized via nuclear magnetic resonance (NMR), mass spectrometry (MS), and elemental analysis. Their liquid crystalline nature and thermal properties were determined using polarized optical microscopy (POM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). A set of seven aromatic amines serving as curing agents was used to perform curing in fourteen different systems in order to assess the glass transition temperature (Tg) of the obtained polymer networks using DSC. The liquid crystalline elastomers were obtained with vitrification occurring in a low temperature range (−10–40 °C), with a more predictable outcome for amines with two aromatic rings in the structure than with one. Moreover, the resin with a core consisting of four aromatic rings produces networks with higher Tg than the three-aromatic resin. The use of nonterminal LCER allowed the lowering of the glass transition temperature of the polymers to more than 70 °C compared to a terminal analogue. This brings new possibilities of designing highly elastic yet cured polymers with potential for use in smart applications due to the LC nature of the resin.

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Section: Introductionmentioning

confidence: 99%

The Effect of Nonterminal Liquid Crystalline Epoxy Resin Structure and Curing Agents on the Glass Transition of Polymer Networks

Kisiel,

Mossety-Leszczak

2024

Polymers

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“…The rapid development of the fifth-generation communication era has led to an increased urgency and higher demands for high-performance dielectric polymeric layers in flexible copper-clad laminates (FCCL). , Since signal transmission speed and efficiency significantly depend on the dielectric constant ( D k ) and dielectric loss ( D f ) of circuit board materials, it is of great importance to develop dielectric polymeric layers with a low D k and low D f at high-frequency regime (>10 GHz). − Along with low dielectric properties, polymeric insulation layers must achieve other requisite properties including thermal stability, chemical stability, flexibility, and low water uptake to ensure the reliability of the FCCL working in the high-frequency regime . Up to now, various polymers including modified polyimide (mPI) and liquid crystal polymer (LCP) have been widely studied as polymeric substrates and dielectric layers for FCCL. − Despite significant progress being made on this front, achieving the aforementioned prerequisite properties still remains a major challenge. In detail, mPI, which has been widely used as electrical insulation layers, has high D f at high-frequency regimes and water uptake, limiting its usage in high-frequency applications. − While LCP demonstrates the potential for exceptional dielectric properties for FCCL in high-frequency regimes and reduced water absorption, the LCP film produced using traditional processing methods inherently showed anisotropic mechanical properties .…”

Section: Introductionmentioning

confidence: 99%

Graft Architectured Poly(phenylene oxide)-Based Flexible Films with Superior Dielectric Properties for High-Frequency Communication Above 100 GHz

Kim,

Park,

Yoo

et al. 2024

ACS Appl. Polym. Mater.

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The surge of fifth-generation communication has intensified the demand for advanced dielectric layers in flexible copper-clad laminates (FCCL). These layers must ensure a low dielectric constant (D k) and dielectric loss (D f) at high frequencies while meeting essential criteria, including thermal and chemical stability, flexibility, and low water uptake to achieve signal transmission efficiency and FCCL reliability. Herein, we have developed flexible dielectric layers based on poly(phenylene oxide)-g-poly(butadiene) (PPO-g-PB) that exhibit low D k and Df values at high-frequency regimes. Two PPO-g-PB samples with different PB graft densities were synthesized to explore the effect of PB side chains on the thermophysical properties of the resulting PPO-g-PB film. The as-synthesized PPO-g-PB demonstrated excellent film-forming ability, allowing for straightforward fabrication through a simple casting process followed by thermal curing. To determine the potential of these dielectric polymers in high-frequency communication applications, dielectric properties of thermally cured PPO-g-PB (TC-PPO-g-PB) were investigated at high-frequency regimes (from 10 to 110 GHz). Furthermore, we also monitored the water uptake behavior and changes in dielectric properties during an 85 °C and 85% relative humidity reliability test to demonstrate the practical application of these dielectric polymers as advanced dielectric materials.

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“…Conventional ceramic dielectric materials, however, cannot satisfy the growing requirements of various application scenarios due to their restricted flexibility and bending characteristics. On the other hand, polymeric materials with outstanding dielectric constants and low dielectric losses, such as liquid crystal polymer (LCP), , polytetrafluoroethylene (PTFE), , and polyimide (PI), − are also utilized. Among these, PI dielectrics are extensively utilized in electronic packaging, aerospace, and several other industries due to their exceptional dielectric and electrical insulating qualities, high chemical stability, and distinctive temperature stability.…”

Section: Introductionmentioning

confidence: 99%

Polyphenol-Functionalized Boron Nitride Nanosheet-Reinforced Sustainable Polyimide Dielectric Films for Antenna-in-Package Applications

Li,

Wang,

Kong

et al. 2024

ACS Appl. Electron. Mater.

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Polyimide (PI) nanocomposite films containing two-dimensional boron nitride nanosheets (BNNSs) have been recognized as advanced dielectrics for flexible and miniaturized integrated circuits and communication electronics. However, highquality BNNSs must be created using lengthy and sophisticated exfoliation and surface functionalization methods, while a PI matrix often undergoes high-temperature imidization, which results in thermosetting properties. These factors pose significant challenges for the manufacture and application of BNNSs/PI dielectrics. Herein, we report a simple yet effective approach to fabricate sustainable BNNSs/PI dielectric films using polyphenol-functionalized BNNSs as the filler and soluble PI (sPI) as the matrix. BNNSs with average size of 2.5 μm in lateral dimension and 2.7 nm in thickness were prepared through a lithium intercalation-assisted liquid-phase exfoliation method. The BNNSs were further modified with polyphenol compounds via noncovalent functionalization. We investigated four different polyphenols, namely, hydroquinone (HQ), dopamine (DP), tannic acid (TA), and tea polyphenol (TP), and found that TP displays a high functionalization density of 0.699 molecule/nm 2 on surfaces of BNNSs, which is about 1 order of magnitude larger than that of TA. Accordingly, TP-BNNSs/ sPI nanocomposites demonstrate superior properties, including a dielectric constant of 3.08 and loss tangent of 0.006 at 100 kHz, electrical breakdown strength of 185.4 kV/mm, and tensile strength of 87 MPa under the filler loading of 1 wt %. Furthermore, the TP-BNNSs/sPI nanocomposite films can be simply recycled at least four times without losing performance. We also demonstrate a coplanar waveguide antenna with the TP-BNNSs/sPI nanocomposite as the dielectric layer, confirming its great potential for practical applications.

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Branched thermotropic liquid crystal polymer with favourable processability and dielectric properties

Cited by 11 publications

References 41 publications

The Effect of Nonterminal Liquid Crystalline Epoxy Resin Structure and Curing Agents on the Glass Transition of Polymer Networks

The Effect of Nonterminal Liquid Crystalline Epoxy Resin Structure and Curing Agents on the Glass Transition of Polymer Networks

Graft Architectured Poly(phenylene oxide)-Based Flexible Films with Superior Dielectric Properties for High-Frequency Communication Above 100 GHz

Polyphenol-Functionalized Boron Nitride Nanosheet-Reinforced Sustainable Polyimide Dielectric Films for Antenna-in-Package Applications

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