Mechanical and Electrical Properties of SomeSilicon-Containing Poly(Amide-Imide)s

Aromatic silicon-containing poly(amide-imide)s have been prepared by low temperature solution polycondensation reaction of various aromatic diamines having ether bridges between phenylene rings with a diacid chloride, namely bis[N-(4-chlorocarbonylphenyl) phthalimidyl]dimethylsilane. These polymers were easily soluble in polar amidic solvents such as N-methylpyrrolidone,N,N-dimethylacetamide, and N,N-dimethylformamide and can be cast from solutions into thin, flexible films. They showed good thermal stability, with initial decomposition temperature being above 410°C and glass transition temperature in the range of 263–285°C. The polymer films exhibited good mechanical properties with tensile strengths in the range of 78–109 MPa, tensile modulus in the range of 1.44–1.76 GPa, and elongation at break values ranging from 11% to 24%. Electrical insulating properties of two polymer films were evaluated on the basis of dielectric constant and dielectric loss and their variation with frequency and temperature.

Keywords:

• Poly(amide-imide)s
• Thin films
• Mechanical properties
• Dielectric properties

ACKNOWLEDGMENTS

Our warm thanks go to Dr. B. Schulz at Potsdam University and Dr. T. Köpnick at the Institute of Thin Film Technology and Microsensors, Teltow, Germany, for valuable discussion in the synthesis of the polymers.

Notes

η_inh = inherent viscosity; T_g = glass transition temperature; IDT = temperature of 5% weight loss; T₁₀ = temperatures of 10% weight loss.

E = elastic modulus; σ_y = yield stress; ϵ_y = yield strain; σ_B = tensile strength; λ_B = draw ratio at break.