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The correlation between surface tension parameters and the chemical composition of poly(amic acid) and polyimide films, before and after plasma treatment, was investigated. Calculations are based on the geometric mean approach according to Owens, Wendt, Rabel, and Kälble, on the Lifshitz‐van der Waals acid/base approach according to Van Oss, Good, and Chaudhury, as well as on the theoretical method which implies the quantitative structure–property relationships. The polar components for all films investigated contribute significantly to the total surface tensions, as due to the large electron‐donor interactions. Plasma treatment alters the surface energy of samples, changing their surface polarity and wettability. Surface wettability and hydrophilicity trends for poly(amic acid)s and their polyimides were also studied by means of the free energy of hydration between compounds and water. These properties recommend the polyimides as excellent materials for electrical compounds and biomaterials. POLYM. ENG. SCI., 47:381–389, 2007. © 2007 Society of Plastics Engineers.

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Surface and electrical properties of two flexible and cross-linked epiclon based polyimide films were investigated. Surface tension measurements indicate an increased hydrophobicity due to both isothermal treatment - which induces imidization and cross-linking - and to the chemical structure, characterized by the different number of ether linkages in the polyimide backbone. Morphology of film surfaces, modified by plasma treatment, shows high roughness and, implicitly, improved adhesion, as required in electronics. The studied polyimides exhibit low dielectric constants and dielectric losses, comparatively to conventional aromatic polyimides. The electrical conductance and resistivity characteristics of these polymers recommend them as good insulators for dielectric layers in microelectronic applications.

Two binary polyimide (PI) blends having a common monomer (diamine or dianhydride) were prepared. The first system was composed of PIs obtained from an alicyclic and flexible dianhydride, namely 5‐(2,5‐dioxotetrahydrofurfuryl)‐3‐methyl‐3‐cyclohexene‐1,2‐dicarboxylic acid anhydride (DOCDA) and two aromatic diamines: 4,4′‐oxydianiline (ODA) and p‐phenylenediamine, respectively. In the second system, ODA was combined with DOCDA and (hexafluoroisopropyldiene)diphthalic dianhydride (6FDA). Films of the resulted blends were transparent, suggesting their homogeneity. According to differential scanning calorimetry data, the existence of a single Tg intermediate to those of the pure PIs confirmed the miscibility of blends. Incorporation of aliphatic and asymmetric DOCDA moieties, hexafluoropropyldiene groups and ether linkages in the molecular structure of PIs reduced the charge transfer interactions and significantly increased transparency and optical gap energy, especially for the poly(DOCDA‐ODA)/poly(6FDA‐ODA) blend. These interactions are also reflected in viscosity dependence on shear rate, indicating that they are slightly stronger when the aromatic 6FDA component prevails. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers