Synthesis and characterization of novel highly soluble and optical transparent polyimides containing tert-butyl and morpholinyl moieties

A series of novel organo-soluble and optical transparent polyimides were synthesized via conventional one-step polycondensation from a novel diamine, 3,3′-diterbutyl-4,4′-diaminodiphenyl-4″-morpholinophenylmethane (TAMPM) and various commercial aromatic dianhydrides. The structures of monomer and polymers were confirmed by FT-IR and NMR. The solubility, thermal stability, optical transparency, dielectric and hydrophobic properties of polyimides were investigated. The results showed polymers presented excellent solubility in common organic solvents, such as N,N-dimethylformamide (DMF), N,N-dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), chloroform (CHCl₃), tetrahydrofuran (THF) and dichloromethane (CH₂Cl₂). The polymers exhibited prominent thermal stability and high optical transparency with the glass transition temperature (T _g) in the range of 311–355 °C, and the cutoff wavelengths in the range of 287–344 nm. Furthermore, all of the polymers also presented low dielectric constants in the range of 2.85–3.16 at 1 MHz, and outstanding hydrophobic properties with the contact angle in the rang of 85.1–94.2 ^o.