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30 pages, 2917 KiB

Open AccessArticle

Solution-Processable Colorless Polyimides Derived from Hydrogenated Pyromellitic Dianhydride: Strategies to Reduce the Coefficients of Thermal Expansion by Maximizing the Spontaneous Chain Orientation Behavior during Solution Casting

by Masatoshi Hasegawa, Katsuki Ichikawa, Shuichi Takahashi and Junichi Ishii

Polymers 2022, 14(6), 1131; https://doi.org/10.3390/polym14061131 - 11 Mar 2022

Cited by 19 | Viewed by 4034

Abstract

In this study, practically useful colorless polyimides (PIs) with low coefficients of thermal expansion (CTEs) and other desirable properties were prepared from hydrogenated pyromellitic dianhydride (1-exo,2-exo,4-exo,5-exo-cyclohexanetetracarboxylic dianhydride, H-PMDA). A modified one-pot polymerization method afforded a [...] Read more.

In this study, practically useful colorless polyimides (PIs) with low coefficients of thermal expansion (CTEs) and other desirable properties were prepared from hydrogenated pyromellitic dianhydride (1-exo,2-exo,4-exo,5-exo-cyclohexanetetracarboxylic dianhydride, H-PMDA). A modified one-pot polymerization method afforded a high-molecular-weight PI with sufficient film-forming ability from 2,2′-bis(trifluoromethyl)benzidine (TFMB) with a rod-like structure and H-PMDA. However, the PI film cast from its homogeneous solution did not have low CTEs, similar to the analogous system using meta-tolidine. To solve this problem, a series of amide- and amide-imide-containing diamines were designed and synthesized. The modified one-pot polymerization of H-PMDA and the diamines in γ-butyrolactone produced homogeneous, viscous, and stable solutions of high-molecular-weight PIs with high solid contents. The cast films of certain systems examined in this study simultaneously achieved low CTEs, high optical transparency, considerably high glass transition temperatures (T_gs), and sufficient ductility. A possible mechanism for the generation of low CTEs, which is closely related to the spontaneous in-plane orientation behavior during solution casting, was proposed. Certain H-PMDA-based PIs developed in this study are promising colorless heat-resistant plastic substrates for use in image display devices and other optical applications. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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11 pages, 2979 KiB

Open AccessArticle

Colorless Polyimides Derived from an Alicyclic Tetracarboxylic Dianhydride, CpODA

by Hiroki Ozawa, Eriko Ishiguro, Yuri Kyoya, Yasuaki Kikuchi and Toshihiko Matsumoto

Polymers 2021, 13(16), 2824; https://doi.org/10.3390/polym13162824 - 22 Aug 2021

Cited by 38 | Viewed by 5218

Abstract

An alicyclic tetracarboxylic dianhydride having cyclopentanone bis-spironorbornane structure (CpODA) was polycondensated with aromatic dianhydrides to form the corresponding poly(amic acid)s which possessed logarithmic viscosities in the range 1.47–0.54 dL/g. The poly(amic acid) was imidized by three methods: a chemical, a thermal, and a [...] Read more.

An alicyclic tetracarboxylic dianhydride having cyclopentanone bis-spironorbornane structure (CpODA) was polycondensated with aromatic dianhydrides to form the corresponding poly(amic acid)s which possessed logarithmic viscosities in the range 1.47–0.54 dL/g. The poly(amic acid) was imidized by three methods: a chemical, a thermal, and a combined chemical and thermal process. In a thermal method, imidization temperature markedly influenced the film quality and molecular weight of the polyimide. When the poly(amic acid) was cured over the Tg of the corresponding polyimide, the flexible polyimide films were obtained and the molecular weights increased several times, which means that the post-polymerization took place. In spite of low-temperature cure below Tg flexible films with the imidization ratio of 100% were fabricated by a combined chemical and thermal imidization technique. The films possessed the decomposition temperatures in a range of 475–501 °C and Tgs over 330 °C. The high Tg results from a dipole–dipole interaction between the keto groups of the polymer chains as well as development of the rigid polyalicyclic unit. The polyimide films exhibited CTE between 17 and 57 ppm/K. All the films fabricated were entirely colorless and possessed the λcut-offs shorter than 337 nm. Notably, the films prepared by a chemical method exhibited outstanding optical properties. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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14 pages, 7604 KiB

Open AccessArticle

The Effect of Molecular Isomerism on the Barrier Properties of Polyimides: Perspectives from Experiments and Simulations

by Yiwu Liu, Fengyun Xie, Jie Huang, Jinghua Tan, Chengliang Chen, Linbing Jiang, Wei Sun and Hailiang Zhang

Polymers 2021, 13(11), 1749; https://doi.org/10.3390/polym13111749 - 27 May 2021

Cited by 10 | Viewed by 2427

Abstract

A novel carbazole-containing diamine (M-2,7-CPDA) isomer of our previously reported diamine 2,7-CPDA, has been synthesized using a two-step synthesis. Compared with 2,7-CPDA, the substituted position of amino is changed from para to meta for M-2,7-CPDA. The two diamines were polymerized with pyromellitic dianhydride [...] Read more.

A novel carbazole-containing diamine (M-2,7-CPDA) isomer of our previously reported diamine 2,7-CPDA, has been synthesized using a two-step synthesis. Compared with 2,7-CPDA, the substituted position of amino is changed from para to meta for M-2,7-CPDA. The two diamines were polymerized with pyromellitic dianhydride (PMDA) to prepare two isomeric polyimides (M-2,7-CPPI and 2,7-CPPI), respectively. The effects of para/meta isomerism on microstructures and gas barrier performances of the two isomeric polyimides were studied by positron annihilation test, X-ray diffraction and molecular simulation. The results display that meta-connected M-2,7-CPPI has less ordered chain structure and weaker hydrogen bonding than para-connected 2,7-CPPI, which leads to loose chain stacking and thereby increased free volumes of M-2,7-CPPI. The higher free volumes promote the solubility and diffusivity of gas in M-2,7-CPPI. As a result, the meta-linked M-2,7-CPPI shows a lower gas barrier than its para-linked analog. The work provides guidance for the design and synthesis of high-performance barrier polymers. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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20 pages, 5360 KiB

Open AccessArticle

“All Polyimide” Mixed Matrix Membranes for High Performance Gas Separation

by Maijun Li, Zhibo Zheng, Zhiguang Zhang, Nanwen Li, Siwei Liu, Zhenguo Chi, Jiarui Xu and Yi Zhang

Polymers 2021, 13(8), 1329; https://doi.org/10.3390/polym13081329 - 19 Apr 2021

Cited by 11 | Viewed by 4621

Abstract

To improve the interfacial compatibility of mixed matrix membranes (MMMs) for gas separation, microporous polyimide particle (AP) was designed, synthesized, and introduced into intrinsic microporous polyimide matrix (6FDA-Durene) to form “all polyimide” MMMs. The AP fillers showed the feature of thermal stability, similar [...] Read more.

To improve the interfacial compatibility of mixed matrix membranes (MMMs) for gas separation, microporous polyimide particle (AP) was designed, synthesized, and introduced into intrinsic microporous polyimide matrix (6FDA-Durene) to form “all polyimide” MMMs. The AP fillers showed the feature of thermal stability, similar density with polyimide matrix, high porosity, high fractional free volume, large microporous dimension, and interpenetrating network architecture. As expected, the excellent interfacial compatibility between 6FDA-Durene and AP without obvious agglomeration even at a high AP loading of 10 wt.% was observed. As a result, the CO₂ permeability coefficient of MMM with AP loading as low as 5 wt.% reaches up to 1291.13 Barrer, which is 2.58 times that of the pristine 6FDA-Durene membrane without the significant sacrificing of ideal selectivity of CO₂/CH₄. The improvement of permeability properties is much better than that of the previously reported MMMs, where high filler content is required to achieve a high permeability increase but usually leads to significant agglomeration or phase separation of fillers. It is believed that the excellent interfacial compatibility between the PI fillers and the PI matrix induce the effective utilization of porosity and free volume of AP fillers during gas transport. Thus, a higher diffusion coefficient of MMMs has been observed than that of the pristine PI membrane. Furthermore, the rigid polyimide fillers also result in the excellent anti-plasticization ability for CO₂. The MMMs with a 10 wt.% AP loading shows a CO₂ plasticization pressure of 300 psi. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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11 pages, 4737 KiB

Open AccessArticle

Copolyamide-Imide Membrane with Low CTE and CME for Potential Space Optical Applications

by Jiajia Yin, Danbo Mao and Bin Fan

Polymers 2021, 13(7), 1001; https://doi.org/10.3390/polym13071001 - 24 Mar 2021

Cited by 12 | Viewed by 2681

Abstract

Polyimide diffractive membrane lens can be used in space optical telescope to reduce the size and mass of an imaging system. However, traditional commercial aromatic polyimide membrane is hard to meet the challenging requirements of dimensional stability and optical homogeneity for optical use. [...] Read more.

Polyimide diffractive membrane lens can be used in space optical telescope to reduce the size and mass of an imaging system. However, traditional commercial aromatic polyimide membrane is hard to meet the challenging requirements of dimensional stability and optical homogeneity for optical use. Based on molecular structure design and the optimization of fabrication process, the prepared copolyamide-imide membrane achieved the desired performance of membrane as an optical material. It showed a very low coefficient of thermal expansion (CTE), which is 0.95 ppm/°C over a temperature range of −150–100 °C and relatively low coefficient of moisture expansion (CME), which is only 13.30 ppm/% RH (0~90% RH). For the optical use, the prepared copolyamide-imide membrane (φ200 mm) achieved good thickness uniformity with wave-front error smaller than λ/30 (λ = 632 nm) in RMS (root mean square). Besides, it simultaneously meets the optical, thermal, and mechanical requirements for space telescope use. Copolyamide-imide membranes in this research with good comprehensive performance can be used as large aperture membrane optical system architectures. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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13 pages, 35751 KiB

Open AccessEditor’s ChoiceArticle

Investigation of the Chemical Structure of Ultra-Thin Polyimide Substrate for the Xenon Flash Lamp Lift-off Technology

by Seong Hyun Jang, Young Joon Han, Sang Yoon Lee, Geonho Lee, Jae Woong Jung, Kwan Hyun Cho and Jun Choi

Polymers 2021, 13(4), 546; https://doi.org/10.3390/polym13040546 - 12 Feb 2021

Cited by 5 | Viewed by 3924

Abstract

Lift-off is one of the last steps in the production of next-generation flexible electronics. It is important that this step is completed quickly to prevent damage to ultrathin manufactured electronics. This study investigated the chemical structure of polyimide most suitable for the Xe [...] Read more.

Lift-off is one of the last steps in the production of next-generation flexible electronics. It is important that this step is completed quickly to prevent damage to ultrathin manufactured electronics. This study investigated the chemical structure of polyimide most suitable for the Xe Flash lamp–Lift-Off process, a next-generation lift-off technology that will replace the current dominant laser lift-off process. Based on the characteristics of the peeled-off polyimide films, the Xe Flash lamp based lift-off mechanism was identified as photothermal decomposition. This occurs by thermal conduction via light-to-heat conversion. The synthesized polyimide films treated with the Xe Flash lamp–Lift-Off process exhibited various thermal, optical, dielectric, and surface characteristics depending on their chemical structures. The polyimide molecules with high concentrations of –CF₃ functional groups and kinked chemical structures demonstrated the most promising peeling properties, optical transparencies, and dielectric constants. In particular, an ultra-thin polyimide substrate (6 μm) was successfully fabricated and showed potential for use in next-generation flexible electronics. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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Review

Jump to: Research

17 pages, 4182 KiB

Open AccessReview

Templated Twist Structure Liquid Crystals and Photonic Applications

by Yao Gao, Weiping Ding and Jiangang Lu

Polymers 2022, 14(12), 2455; https://doi.org/10.3390/polym14122455 - 16 Jun 2022

Cited by 12 | Viewed by 2638

Abstract

Twist structure liquid crystals (TSLCs) have attracted increasing attention in photonic applications due to their distinct properties: Bragg reflection, scattering, and optical rotation. However, there exist some issues due to the defects of TSLCs: weak thermal stability, narrow bandwidth, and complicated fabrication. In [...] Read more.

Twist structure liquid crystals (TSLCs) have attracted increasing attention in photonic applications due to their distinct properties: Bragg reflection, scattering, and optical rotation. However, there exist some issues due to the defects of TSLCs: weak thermal stability, narrow bandwidth, and complicated fabrication. In this review, we introduce the templating technique which includes device structure, templating process, and photonic properties of templated TSLCs to improve the issues. Furthermore, a variety of photonic applications including lasing, optical filters and gratings based on TSLCs with polymer templates are presented. Additionally, other applications of TSLCs are briefly introduced. Finally, the remaining challenges and future perspectives of templated TSLCs are proposed. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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34 pages, 111731 KiB

Open AccessReview

Progress in Aromatic Polyimide Films for Electronic Applications: Preparation, Structure and Properties

by Ziyu Wu, Jianjun He, Haixia Yang and Shiyong Yang

Polymers 2022, 14(6), 1269; https://doi.org/10.3390/polym14061269 - 21 Mar 2022

Cited by 90 | Viewed by 11409

Abstract

Aromatic polyimides have excellent thermal stability, mechanical strength and toughness, high electric insulating properties, low dielectric constants and dissipation factors, and high radiation and wear resistance, among other properties, and can be processed into a variety of materials, including films, fibers, carbon fiber [...] Read more.

Aromatic polyimides have excellent thermal stability, mechanical strength and toughness, high electric insulating properties, low dielectric constants and dissipation factors, and high radiation and wear resistance, among other properties, and can be processed into a variety of materials, including films, fibers, carbon fiber composites, engineering plastics, foams, porous membranes, coatings, etc. Aromatic polyimide materials have found widespread use in a variety of high-tech domains, including electric insulating, microelectronics and optoelectronics, aerospace and aviation industries, and so on, due to their superior combination characteristics and variable processability. In recent years, there have been many publications on aromatic polyimide materials, including several books available to readers. In this review, the representative progress in aromatic polyimide films for electronic applications, especially in our laboratory, will be described. Full article

(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)

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