Larry L. Berger

Effects of polyimide chemical structure and environment on the diffusivity of copper

Abstract Rutherford backscattering spectrometry was used to study the diffusion of copper into three fully imidized polyimides of differing chemical structure, electrophilicity and T g . Samples were exposed to heat treatment in the different atmospheric environments of air, N 2 and vacuum (10 −8 Torr). The coefficients D of the diffusion of copper oxide into the polyimide hosts was −18 cm 2 s −1 when the samples were annealed under high vacuum conditions. In contrast, for samples annealed in a nitrogen atmosphere, the D value was orders of magnitude higher and its temperature dependence varied with T −1 . Under these conditions, comparable diffusivities of copper oxide were observed in each of the polyimides. Moreover, when the polyimide samples were annealed in air, still higher values of D were found. For these samples, however, we were able to show conclusively that the degradation of the polyimide was considerable.

Effects of chain structure on the melting characteristics of poly(vinyl fluoride)

Abstract The effects of configurational disorder and chain branching on the melting characteristics of the addition polymer poly(vinyl fluoride) (PVF) have been investigated. For PVF, the melting point (Tm) was found to be strongly dependent on polymerization temperature, and only weakly dependent on polymerization pressure. Structural investigation of the polymer backbone using 19F nuclear magnetic resonance analysis reveals that the pronounced increase in Tm results predominantly from a decrease in chain branching and, to a far lesser extent, from improved main-chain regio-regularity. For PVF with a (tertiary fluorine) branch-point content above 2.2% (∼ one branch per 45 monomer additions) the melting point is reduced to below 180°C, whereas for samples with branch-point content less than 0.3% (∼ one branch per 300 monomer additions) the melting point lies above 205°C. Moreover, for the same polymers, the number of head-to-head monomer linkages was found to remain largely constant (= 12.5 ± 1%).