Synthesis and Properties of Optically Transparent Fluoro-Containing Polyimide Films with Reduced Linear Coefficients of Thermal Expansion from Organo-Soluble Resins Derived from Aromatic Diamine with Benzanilide Units

Abstract

Wholly aromatic polyimide (PI) films with good solution processability, light colors, good optical transparency, high storage modulus, and improved heat resistance were prepared and characterized. For this purpose, a multi-component copolymerization methodology was performed from a fluoro-containing dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), a rigid dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and a fluoro-containing diamine, 2,2′-bis(trifluoromethyl)-4,4′-bis [4-(4-amino-3-methyl)benzamide]biphenyl (MABTFMB). One homopolymer, FPI-1 (6FDA-MABTFMB), and five copolymers, FPI-2~FPI-6, containing the BPDA units from 10 mol% to 50 mol% in the dianhydride moieties, were prepared, respectively. The derived PI resins showed good solubility in the polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). The flexible PI films obtained by the solution casting procedure showed good optical properties with the transmittances higher than 74.0% at the wavelength of 450 nm. The PI films exhibited excellent thermal properties, including 5% weight loss temperatures (T5%) over 510 °C, together with glass transition temperatures (Tg) over 350.0 °C according to the peak temperatures of the loss modulus in dynamical mechanical analysis (DMA) measurements. The FPI-6 film also showed the lowest linear coefficient of thermal expansion (CTE) value of 23.4 × 10−6/K from 50 to 250 °C according to the thermomechanical analysis (TMA) measurements, which was obviously lower than that of FPI-1 (CTE = 30.6 × 10−6/K).

Preparation and characterization of colorless and transparent semi‐alicyclic fluoro‐containing polyimide nanocomposite films with enhanced high‐temperature dimensional stability via incorporation of colloidal silica nanofillers

“…By this strategy, various amide‐bridged or polyamideimide (PAI) types of CPI films were developed in the literature 16–25 . Although the incorporation of the rigid amide units could efficiently decreased the CTE values of the afforded CPI films, the deterioration of the optical properties, including the decreasing optical transmittance in the visible light region, the increasing yellow indices, and the increasing optical retardation of the CPI films are still observed in our previous work 26–28 . This might be due to the enhanced charge transfer (CT) interactions in the molecular structures of the amide‐bridged CPIs caused by the highly conjugated and polar structures of the amide or benzanilide units 29 .…”

“…[16][17][18][19][20][21][22][23][24][25] Although the incorporation of the rigid amide units could efficiently decreased the CTE values of the afforded CPI films, the deterioration of the optical properties, including the decreasing optical transmittance in the visible light region, the increasing yellow indices, and the increasing optical retardation of the CPI films are still observed in our previous work. [26][27][28] This might be due to the enhanced charge transfer (CT) interactions in the molecular structures of the amide-bridged CPIs caused by the highly conjugated and polar structures of the amide or benzanilide units. 29 In view of the limitation of the structural modification for the low-CTE CPI films, the composition modification; that is the low-CTE nanocomposite CPI films have attracted increasing attentions in recent years.…”

Preparation and Characterization of Light-Colored Polyimide Nanocomposite Films Derived from a Fluoro-Containing Semi-Alicyclic Polyimide Matrix and Colloidal Silica with Enhanced High-Temperature Dimensionally Stability

“…However, the optical properties of the derived low-CTE CPI films deteriorated with the incorporation of the amide components. In view of this defect of the common CPI films derived from the amide-containing diamines, a novel aromatic diamine simultaneously containing rigid-rod benzanilide and highly electronegative trifluoromethyl (–CF 3 ) units, 2,2′-bis (trifluoromethyl)-4,4′-bis[4-(4-aminobenzamide)]biphenyl (ABTFMB) was designed and developed in Hasegawa’s group and was widely used to develop high-performance CPI films [ 24 , 25 , 26 ].…”

Preparation and Characterization of Light-Colored Polyimide Nanocomposite Films Derived from Fluoro- Containing Semi-Alicyclic Polyimide Matrix and Colloidal Silica with Enhanced High-Temperature Dimensionally Stability

“…However, the optical properties of the derived low-CTE CPI films were deteriorated by the incorporation of the amide components. In view of this defect of the common CPI films derived from the amide-containing diamines, a novel aromatic diamine simultaneously containing rigid-rod benzanilide and highly electronegative trifluoromethyl (-CF3) units, 2,2'-bis (trifluoromethyl)-4,4'bis[4-(4-aminobenzamide)]biphenyl (ABTFMB) was designed and developed in Hasegawa's group and was widely used to develop high-performance CPI films [24][25][26].…”