Novel acetylene‐terminated polyimide oligomers with excellent processability and high toughness of films

Abstract

A series of acetylene-terminated imide oligomers based on 2,3,3 0 ,4 0 -Diphenyl ether tetracarboxylic acid dianhydride (a-ODPA), 3,4 0 -Oxydianiline (3,4 0 -ODA), and 3-Ethynylaniline (3-EA) with different molecular weights were synthesized by using acetic anhydride and triethylamine as dehydrating agent. Their main structure was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal curing processing was characterized by FT-IR and differential scanning calorimetry (DSC). All the uncured imide oligomers showed excellent solubility (more than 30 wt %) in organic solvent such as N,N-dimethylacetamide (DMAc) and Nmethyl-2-pyrrolidone (NMP). These imide oligomers also possessed a very low viscosity, thus provided better processing window. These oligomers were formulated into thermosetting films by thermal crosslinking of the ethynyl groups. The properties of cured films were evaluated by dynamic mechanical thermal analysis (DMA), thermogravimetric analysis (TGA), and tensile measurement. The glass transition temperature (T g ) and elongation at break of the cured films were found to be almost >2608C and >9.2%, respectively. The cured films in air resulted in higher thermal stability than those under N 2 atmosphere. Experimental results suggested that the introduction of asymmetric and flexible ether-hinge with 3-EA in polyimide oligomers can improve the processability of the imide oligomers and the toughness for a cured sample without sacrificing their thermal-oxidative stability.

HighTgand Thermo‐Oxidatively Stable Thermosetting Polyimides Derived from a Carborane‐Containing Diamine

“…In the field of advanced polymers, thermosetting polyimides (PIs) occupy a preponderant position due to their excellent chemical stability, thermal and mechanical properties . Thermosetting PIs are being designed for aerospace applications to meet the expectation of performance and durability in high temperature oxidative environments .…”

“…In the field of advanced polymers, thermosetting polyimides (PIs) occupy a preponderant position due to their excellent chemical stability, thermal and mechanical properties. [1][2][3][4][5][6] Thermosetting PIs are being designed for aerospace applications to meet the expectation of performance and durability in high temperature oxidative environments. [7][8][9][10][11][12][13] It is well known that, the glass transition temperature (T g ) is a fundamental characteristic of any thermoset, and polymers with higher T g are actively sought for a variety of high-performance applications.…”

Oxidatively stable thermosets derived from thermal copolymerization of acetylene-terminated imide monomer with an acetylenic monomer containing carborane

“…m-EFDA was synthesized by the reaction of 3-EA with 6-FDA and subsequently cyclodehydrated by chemical imidization with acetic anhydride and triethylamine according to a published method (Scheme 1). [10] In this work, we chose to use 3-ethynylbenzeneamine instead of 4-ethynylbenzeneamine because imide oligomers end-capped with 4-ethynylbenzeneamine exhibit significantly higher softening temperatures and fail to cure properly, which has been qualified by early work. [39] Chemical structures of APCB and m-EFDA were confirmed by FT-IR, 7 1 H-NMR, 13 C-NMR and mass spectrometry.…”

“…The acetylene terminated monomer was synthesized according to a published method (Scheme 1). [10] A flame-dried 100 mL three-necked round bottom flask equipped with a magnetic stirrer, a nitrogen inlet and a reflux condensing tube was charged with 3.51 g (30 mmol) of 3-EA and 30 mL NMP. 6.66 g (15 mmol) of 6-FDA resolved in 20 mL NMP was then added and the reaction mixture was stirred at room temperature for 2h.…”

Synthesis and characterization of asymmetric bismaleimide oligomers with improved processability and thermal/mechanical properties

“…Solubility of the oligomers OD-BMI-1, OD-BMI-2, BP-BMI-1, and BP-BMI-2 in various solvents with 10 wt% of solid content at ambient temperature was summarized in Table 3. These results indicate that introducing the asymmetric groups and ether groups to the oligomer chains indeed significantly improve the solubility in a range of solvents including 1,4-dioxane and chloroform with low boiling point [15][16][17]. Figure 7 showed the solubility of OD-BMI-1 oligomer with 50 wt % in DMAc solvent.…”