Characterization and Studies of Designed Photodefinable CoPoly(amic Acid) Ionic Salt Solutions

• Published in: International journal of polymer analysis & characterization 2004-01, Vol.9 (1-3), p.177-196
• Main Authors: Vora, Rohitkumar H., Santhana Gopala Krishnan, P., Veeramani, S.
• Format: Article
• Language: English
• Subjects: Amic acid ionic salt; Photodefinable polyimides; Poly(amic acid); Poly(amic acid) ionic salt; Viscosity stability and Thermal degradation studies
• ISSN: 1023-666X; 1563-5341
• DOI: 10.1080/10236660490891320

In an attempt to develop a very stable photodefinable ionic salt solution, we synthesized two series of co-poly(amic acid)s (CoPAAs) by reacting 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) or 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) with various mole percents of ortho-Tolidine (o-TDA) and 1,3-bis(3-aminopropyl) tetramethyl disiloxane (SiDA). Subsequently, two series each of the ionic bond type photodefinable co-poly(amic acid) salts (CoPAS) were made, using 2-(diethylamino)ethyl methacrylate (DEEM) and 2-(dimethylamino)ethyl methacrylate (DMEM). NMR studies were carried out on bisphthalamic acid of o-TDA and SiDA model compounds to identify weak linkage in the above PAAs. Bulk viscosity, inherent viscosity, acid number, and molecular weight of CoPAA and CoPAS solutions decreased drastically as the storage time increased. CoPAS was less stable than CoPAA. BPDA-based PAA showed less viscosity drift than the BTDA-based PAA. Both CoPAA and CoPAS samples showed a two-step weight loss in air atmosphere. The first step was attributed to imidization and the second step to thermal degradation. The activation energy for thermal degradation was determined using Coats-Redfern and Chang methods and the values were found to be comparable.