Synthesis and properties of thermostable naphthalate-containing copoly(amide–imide)s

✍ Scribed by Huei-Hsiung Wang; Wei-Pun Lin

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 267 KB
• Volume: 65
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970822)65:8<1581::aid-app15>3.0.co;2-z

✦ Synopsis

Thermostable naphthalate-containing copoly(amide-imide)s with inherent viscosity of 0.53-0.96 dL/g were synthesized by reacting diacid-terminated naphthalate monomers with various diisocyanate-terminated polyimide prepolymers. The polyimide prepolymers were prepared by using 4,4-diphenylmethane diisocyanate to react with 3,3,4,4-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, or 3,3,4,4-sulfonyl diphthalic anhydride using a direct one-pot method to improve their solubility without sacrificing their thermal properties. The copolymers, except the B-2 and P-2 series, can be dissolved in N,N-dimethylacetamide and 5% lithium chloride or dimethyl sulfoxide at high temperature but are not soluble in pyridine. The solubility of the copolymers is related to their chemical and crystalline structures. Those copolymers with sulfonyl or amorphous structures display good solubility. All the naphthalate-containing copoly(amide-imide)s have glass transition temperatures and melting points in the range of 223-312ЊC and 348-366ЊC, respectively, and show a 10% weight-loss temperature of 485-549ЊC in air and 465-564ЊC in a nitrogen atmosphere. The tensile strength, elongation at break, and initial modulus of polymer films range from 25-74 MPa, 4-9%, and 0.74-1.60 GPa, respectively. From the X-ray diffraction studies, copolymers of B-2, P-2, and D-2 with symmetrical 2,6-naphthalate amide structure are crystalline, but the others are amorphous.