N, N′-bis(4-ethynyl phenyl) 1,4,5,8-naphthalimide: a new monomer for a high Tg heat-resistant polymer

• Published in: Polymer (Guilford) 1994, Vol.35 (15), p.3305-3310
• Main Authors: Melissaris, Anastasios P, Litt, Morton H
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; heat resistance; Organic polymers; Physicochemistry of polymers; polyimide; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; thermal polymerization
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/0032-3861(94)90139-2

A new 4-ethynyl-substituted monomer, bis(4-ethynyl phenyl) 1,4,5,8-naphthalimide (EPNI) was synthesized and characterized. EPNI is a crystalline material which, when thermally polymerized under N 2 in the solid state, yielded a highly crosslinked resin. The progress of polymerization was followed by Fourier transform i.r. spectroscopy, differential scanning calorimetry and wide-angle X-ray diffraction. It was found that EPNI reacted completely thermally to yield an extended polyene structure. Polymer plates were made by solid-state polymerization of EPNI under 4.8 MPa for 1.5 h at 300°C. Because EPNI is ordered and polymerized in the crystalline state, it showed zero polymerization shrinkage (EPNI had the same density as the well consolidated polymer, 1.40 g ml −1). EPNI polymerized to high conversion in spite of its very rigid matrix, probably because of the localization of its polymerizable ethynyl groups. A plate of polymeric EPNI (PEPNI) with 10% voids had a storage modulus of 2.2 GPa at room temperature, a glass transition temperature, T g of 309°C and a linear coefficient of thermal expansion of 4.28 × 10 −5 K −1. PEPNI has excellent thermal and thermooxidative stabilities since it retained over 83% of its initial weight after 105 h at 427°C in air.