We investigate the effect of surface energy and chain architecture on the orientation of microdomains in relatively thick films (600−800 nm) of lamellar and cylindrical block copolymers of poly(cyclohexylethylene) (C) and poly(ethylene) (E). The E block has 26 ethyl branches per 1000 backbone carbon atoms. Melt surface energies of the C and E blocks are 22.3 and 20.9 mJ/m2, respectively. Grazing-incidence small-angle X-ray scattering (GISAXS), scanning force microscopy (SFM), and cross-sectional transmission electron microscopy (TEM) show that cylindrical and lamellar CEC triblock copolymers orient their microdomains normal to the surface throughout the film thickness. However, a lamellar CE diblock copolymer prefers a parallel orientation of the lamellae relative to the surface with an E surface layer. Moreover, a cylindrical CEBC triblock copolymer where the EB block has 125 ethyl branches per 1000 backbone carbon atoms leads to EB cylinder domains that always orient parallel to the surface. In this case the lower surface energy EB block dominates the surface. Calculations using self-consistent-field theory allow us to interpret the experimental results in terms of the entropic cost of forming a wetting layer comprised entirely of looping blocks. Thus, in triblock copolymers, parallel orientations are only stabilized when the midblock has the lower surface energy, and the difference in surface energies of the two blocks is large enough to compensate for this conformational penalty, which is absent in diblock copolymers.

A magnetic suspension balance was employed in experiments to measure gas solubility in the polymer melts. The gas solubilities of CO 2 and N 2 in both linear and branched Polypropylene (PP) were investigated. The swollen volumes predicted by the Sanchez-Lacombe equation of state (EOS) and Simha-Somcynsky EOS were applied to incorporate the buoyancy effect, which is essential for the accurate measurement of solubility data. The effects of the branched structure on the swollen volume and gas solubility were discussed. It was observed that the long chain branched PP exhibited less expandability than the linear PP, due to the entangled molecular chain structure. Therefore, the total amount of gas that was able to dissolve into the long chain branched PP turned out to be less.