Facile and efficient preparation of phosphinate-functionalized aromatic diamines and their high-T g polyimides

The Synergistic Effect of Triazine and Phosphaphenanthrene Units on the Physico-Chemical Behavior of Polyimides

With the aim to develop polymers with appealing, multifunctional characteristics, a series of polyimides were designed by anchoring 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) units on the main polymer chains containing 1,3,5-triazine and several flexible moieties, such as ether, hexafluoroisopropylidene, or isopropylidene. A detailed study was conducted to establish structure-property correlations, with a focus on the synergistic effectiveness of triazine and DOPO moieties on the overall features of polyimides. The results evidenced good solubility of the polymers in organic solvents, their amorphous nature with short-range regular-packed polymer chains, and high thermal stability with no glass transition temperature below 300 °C. Spectrophotometric measurements revealed the existence of a strong charge transfer complex in these polymers that led to a "black" appearance, which generated broad absorption bands spanning on the overall visible range. Nevertheless, these polymers displayed green light emission associated with 1,3,5-triazine emitter. The electrochemical characteristics of the polyimides in solid state demonstrated their strong n-type doping character induced by three different structural elements with electron-acceptance capability. The useful properties of these polyimides, including optical, thermal, electrochemical, aesthetics, and opaqueness, endow them with several possible applications in the microelectronic field, such as protecting layers for the inner circuits against UV light deterioration.

Phosphine oxide based polyimides: structure–property relationships

The PI flame retardance has been influenced by the variation of flexible segments leading to a reduction of THR.

Electron-withdrawing/donating effects of substituents on the preparation of phosphinated 4,4′-diaminodiphenylmethane for soluble, anti-oxidative, and high-Tg polyimides

In this work, we reveal a strategy to prepare a phosphinated 4,4′-diaminodiphenylmethane, 1,1-bis(4-aminophenyl)-1-(6-oxido-6H-dibenz <c, e<,2> oxaphosphorin-6-yl)methane (3). During the preparation, it was found that the effect of the electron withdrawing/donating characteristic of substituents is crucial to the synthesis. A reaction mechanism including nucleophilic addition, reduction, and electrophilic substitution is proposed. Based on diamine (3), a series of polyimides (4a–4d) were prepared. Polyimides 4 are readily soluble in some organic solvents, and can be solution cast into flexible and foldable films. They show high Tg (310–390°C), high moduli (3.34–4.63 GPa), moderate coefficient of thermal expansion (46–58 ppm °C−1), good anti-oxidative stability ( Td 5%: 480–537°C (N2); 456–504°C (air)), and good flame retardancy (VTM V-0 rating).

Synthesis and evaluation of properties of novel aromatic poly(ether-imide) with benzazole pendent groups and flexible ether linkages

Three types of new bis(ether-amine) monomers such as 5-(2-benzimidazole)-1,3-bis(4-aminophenoxy)benzene (3), 5-(2-benzoxazole)-1,3-bis(4-aminophenoxy)benzene (4), and 5-(2-benzothiazole)-1,3-bis(4-aminophenoxy)benzene (5) were prepared in three steps, starting from the reaction of 3,5-dihydroxybenzioc acid with 4-fluronitrobenzene in N, N-dimethylformamide (DMF) solution in the presence of potassium carbonate, followed by catalytic reduction of the intermediate dinitro-carboxylic acids, and subsequent condensation of the resulting diamino-carboxylic acids and 1,2-phenylenediamine, 2-aminophenol or 2-aminothiophenol in polyphosphoric acid (PPA), respectively. Three series of modified poly(ether-imide)s (PEIs) bearing pendent benzimidazole, benzoxazole or benzothiazole groups were prepared from the bis(ether-amine)s with dianhydrides by a conventional two-stage process that included ring-opening polycondensation forming the poly(amic acid)s (PAA) and further thermal or chemical imidization forming poly(ether-imide)s. For comparative purposes, reference poly(ether-imide)s were also prepared by reacting bis(ether-amine) lacking pendent groups namely 1,3-bis(4-aminophenoxy)benzene (6) with the same dianhydrides under similar conditions. The modified polymers were obtained in quantitative yields with inherent viscosities between 0.52 and 0.83 dL g−1. Experimental results indicated that all the PEIs had glass transition temperature between 221 and 283 °C, the decomposition temperature at 10% weight loss between 480 and 572 °C under nitrogen.