Search

A new highly aromatic hardener, phenylated phenylenediamine (PDA), was synthesized utilizing a Diels‐Alder reaction to afford a mixture of para and meta conformations. This new hardener was cured with bisphenol A diglycidyl ether (BADGE). To investigate the conformational mixture, pure 1,4‐benzenediamine and 1,3‐benzenediamine were cured with BADGE. DSC was employed to observe cure curves affording the onset (73, 74, and 146°C for 1,4‐benzenediamine, 1,3‐benzenediamaine, and phenylated phenylenediamine, respectively), peak (128, 151, and 206°C, respectively), and enthalpy change (385, 526, and 238 J/g, respectively), as well as the glass transition temperature (103, 151, and 212°C, respectively). ATR‐FTIR spectroscopy provided information on the structures of the cured network samples, including loss of oxirane and primary amine vibrations after curing. TGA and DMA were used to determine thermal stability (Td,N2 = 332, 367, and 380°C, respectively) and thermal mechanical properties including storage (E′ = 200, 150, and 350 MPa, respectively), loss modulus (E″ = 10, 10, and 40 MPa, respectively), and tan delta (102, 180, and 209°C, respectively). [ABSTRACT FROM AUTHOR]

New naphthalene‐ and perylene‐containing polyarylene poly(amic acid)s and polyimides were synthesized from a new phenylated phenylenediamine. A small‐molecule model compound was also synthesized with naphthalene end‐groups. The new compounds were characterized, and the structures were confirmed using 1H NMR and attenuated total reflectance Fourier transform infrared spectroscopy. Thermal characterization was conducted using thermogravimetric analysis and differential scanning calorimetry. Onset of thermal degradation temperatures for the naphthalene and perylene polyimides were 561 and 545 °C, and char yields at 1000 °C were 61 and 59% (under nitrogen), respectively. The glass transition temperatures were 381 and 396 °C, respectively. Molecular weights determined using gel permeation chromatography were Mw = 35 000 and 24 000 g mol−1, respectively. The absorption maxima were at 387 and 427/458/491/527 nm, respectively, while the fluorescence emission maxima were at 498 and 541/582 nm, respectively. Nanoparticles were prepared from these new fluorescent dye‐containing polyarylene polyimides with sizes of 102/397 and 177 nm, respectively, as determined using dynamic light scattering. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

The synthesis of new bis(pyridylethynyl) ligands is investigated in which the two pyridylethynyl moieties are separated by organosilicon spacers. The difference in flexibility between the two spacers is apparent on examination of the various bond angles in the complexes.

ABSTRACT A series of silyl ether amine curing agents were synthesized by selective substitution reactions of chloroalkylsilanes or the transetherification of alkoxysilanes. Crosslinked networks were prepared by mixing a stoichiometric ratio of bisphenol A diglycidyl ether (D.E.R 331) with the amine curing agents. The networks were characterized by ATR-FTIR spectroscopy, TGA, DSC, and DMA. The onset of thermal degradation, glass transition temperatures, and storage moduli for the networks were 350 °C, 70-108 °C, and 5-25 MPa, respectively. The degradation behavior of the cured samples was monitored for 30 days in PBS, NaOH 5% (w/v), and HCl 5% (v/v) solutions and the degradation products were characterized by spectroscopic methods. The thermal, mechanical, and degradation studies indicated that crosslink density, Tg, storage modulus, and the rate of degradation were affected by the functionality of the amine curing agents and the number of hydrolyzable silyl ether bonds present per mole of curing agent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44620. [ABSTRACT FROM AUTHOR]