Synthesis and properties of thermoplastic polyimides with ether and ketone moieties

Abstract

A series of polyimides containing ether and ketone moieties were synthesized from 1,3‐bis(4‐fluorobenzoyl) benzene and several commercially available dianhydrides via a conventional two‐step polymerization. The inherent viscosities of Polyamide acids ranged from 0.46 to 0.73 dL/g. Thermal properties, mechanical properties, and thermalplasticity of the obtained polimide films were investigated by focusing on the chemical structures of their repeat units. These films were amorphous, flexible, and transparent. All films displayed low Tgs (184–225 °C) but also excellent thermal stability, the 5% weight loss temperature was up to 542 °C under nitrogen. The films showed outstanding mechanical properties with the modulus up to 3.0 GPa and the elongation at break in the range of 8–160%. The uniaxial stretching of PI‐a at high temperature was studied owing to its excellent flexibility. The PI‐a had an elongation at break up to 1600% at 245 °C and the uniaxially stretched film exhibited a much higher modulus (3.9 GPa) and strength (240 MPa) than undrawn film. The results indicated that PI‐a can potentially be used to prepare materials such as fiber, ultra‐thin film or ultra‐high modulus film. All the obtained films also demonstrated excellent thermoplasticity (drop of E′ at Tg > 103) which made the polyimides more suitable for melt processing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2878–2884, 2010

Frontal polymerization preparation of poly(acrylamide‐co‐acrylic acid)/activated carbon composite hydrogels for dye removal

“…Alzari et al synthesized stimuli responsive hydrogels via FP from N ‐isopropylacrylamide and N ‐vinylcaprolactam 18. Chen and coworkers reported a facile strategy for quickly fabricating poly(2‐hydroxypropyl acrylate–vinyl versatate) amphiphilic hydrogels toward removal of toxic solvents by FP 19. Very recently, in our previous research,20 poly(acrylic acid–acrylamide) hydrogels were investigated to be prepared by FP technique and used for cationic dyes removal.…”

Preparation and characterization of inherently heat‐sealable polyimides with high glass transition temperatures

“…DMA is an effective method of characterizing the thermoplasticity of PI film, since the change of storage modulus ( E′ ) around T g is affected by the chain mobility . As shown in Figure , the E' s of the CPI films dropped rapidly and the dropped amplitudes are above 10 3 MPa °C −1 , indicating that they are in possession of good thermoplasticity and thus the heat‐sealable potential. This favorable property should originate from the high free volume and weak chain interaction caused by the distorted structure of aODPA.…”

Synthesis and Characterization of New Organosoluble and Thermally Stable Poly(thioether-amide)s Bearing Pyridine Subunit in the Main Chain

“…The IR spectrum of diacid (5, PDA) is presented in Figure 1. The polymerizations were carried out via Yamasaki phosphorylation reaction, by the reaction of diacid (5) and different diamines in the presence of triphenyl phosphite (TPP), pyridine (Py), N-methylpyrrolidinone (NMP), and calcium chloride (CaCl 2 ), under microwave irradiation almost in quantitative yields (Table 1). Polymers were precipitated in boiling methanol and washed with hot water and methanol, respectively.…”

“…The reaction mixture was stirred at room temperature for 24 h. After completion of the reaction (monitored by TLC), water was added and the reaction mixture was neutralized with HCl solution. After standing for 2 h, the resulting precipitate was filtered and recrystallized in ethanol to obtain diacid (5) room temperature, the resulting viscose reaction mixture was poured into 300 mL of boiling methanol. The resulting crude product was precipitated and then filtered.…”

“…There has been an increased attention in the preparation of polyamides with different substituents or structural irregularities to improve their process ability without lowering their other desired properties. These studies include entering flexible adducts into the polymer main chain [5][6][7], replacing symmetrical aromatic rings by unsymmetrical ones [8][9][10], introducing bulky and reliable pendent groups to minimize crystallization [11][12][13][14][15], and forming a noncoplanar and nonsymmetrical structure [16][17][18].…”