Synthesis and properties of novel flame‐retardant poly(amide‐imide)s containing phosphine oxide moieties in main chain by microwave irradiation

Abstract

Eight new flame-retardant poly(amide-imide)s with high inherent viscosities containing phosphine oxide moieties in main chain were synthesized from the polycondensation reaction of N,NЈ-(3,3Ј-diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7, with eight ;aromatic diamine 8a-h by two different methods such as solution and microwave-assisted polycondensation. Results showed that the microwave-assisted polycondensation by using a domestic microwave oven proceeded rapidly, compared with solution polycondensation and were completed within about 10 -12 min. The resulting poly-(amide-imide)s 9a-h showed high thermal stability and flame-retardant properties. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties of the PAIs 9a-h were investigated by using thermal gravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetry (DSC). Char yield measurements at 600°C demonstrated that incorporating phosphine oxide moieties in polymer backbone markedly improves their flame retardancy. All of the earlier polymers were soluble at room temperature in various organic solvents such as NMP, DMF, DMSO, DMAc, and concentrated sulfuric acid.

Recent Advances in Microwave-Assisted Polymer Synthesis

“…Similar results were found for the MW-assisted polycondensation of different N,N -(4,4 -oxydiphthaloyl)-bis(amino acid chloride)s with aromatic amines, [99][100][101][102][103] of different N,N -(4,4 -hexafluoroisopropylidenediphthaloyl)-bis(amino acid chloride)s with aromatic amines, [104,105] of N,N -(4,4 -diphenylether)-bis(trimellitimide acid chlorides)s with hydantoin derivatives, [106] of N,N -(4,4 -sulfonediphthaloyl)-bis(amino acid chloride)s with aromatic amines [107,108] as well of epiclon-based diamino acid chlorides with aromatic amines. [109][110][111][112] The corresponding conversion of N,N -(3,3 -triphenylphosphine oxide)-bis(trimellitimide acid chloride) with different aromatic amines [113] and hydantoin derivatives [114] yielded poly(amide-imide)s with flame retardant properties. Mallakapour and Rafiemanzelat presented the MW-assisted conversion of N-trimellitylimido-l-valine [115] and bis(p-amido benzoic acid)-N-trimellitylimido-l-leucine [116] with aliphatic and aromatic diisocyanates to yield optically active poly(amide-imide)s. The influence of different solvents and MW irradiation time on polymer yield was studied.…”

New photosensitive poly(amid‐imide)s containing chalcone moiety and hydantoin derivatives in the main chain: Synthesis and characterization

“…These polymers had inherent viscosities of 0.26-0.42 dL/g. Inherent viscosities of resulting PAs 8a-f were measured by a standard procedure using a Technico Regd Trad Merk Viscometer at a concentration of 0.5g/dL in DMF as solvent at 25 C. These polymers confirmed to be PAIs with FTIR spectroscopy and elemental analyses (Table II). A representative FTIR spectrum of PAI 8e is shown in proposed structures (Table II).…”

Novel Flame‐Retardant and Thermally Stable Poly(Amide‐imide)s Based on Bicyclo[2,2,2]oct‐7‐Ene‐2,3,5,6‐Tetracarboxylic Diimide and Phosphine Oxide in the Main Chain: Synthesis and Characterization

“…According to the synthetic procedure reported previously, [23][24] bis(3-amino phenyl) phenyl phosphine oxide 4 was prepared from bis(3-nitro phenyl) phen- acids 2a-f, 50 mL of acetic acid and a stirring bar were placed into a 250-mL round-bottomed flask. The mixture was stirred at room temperature overnight and refluxed for 4 hrs.…”