Morphological effects on molecular mobility have been studied for solid ultrahigh molecular weight polyethylenes (UHMW-PE) crystallized from the melt and from solution or during polymerization. On the basis of transmission electron microscopic (TEM) observation, a crystalline domain structure was well identified for nascent UHMW-PE powders, which is quite different from regular lamellar stacking for solution-crystallized samples and the usual spherulites for melt-crystallized samples. Nuclear magnetic resonance (NMR) results showed that the amorphous chains between these crystalline domains in nascent powders were constrained, as well as those sandwiched between stacked crystalline lamellae for the solution-crystallized sample. Also, the existence of three regimes was recognized in the relaxation behavior of the crystalline phase, as revealed by 1H pulse NMR measurements. In process 1 (heating from room temperature), activation of molecular motion at the boundary between crystal/amorphous regions takes place. During process 2 (above the critical temperature of 60−90 °C), the crystallinity increases with the acceleration of the entire molecular motion caused by sliding of molecular chains in the crystalline region. Further raising the temperature (process 3) leads to the start of sample melting. These relaxation mechanisms suggest that the accelerated molecular motion in the crystal/amorphous boundaries initiates following lamellar thickening without passing the melt state.

Block copolymer is capable of organizing various selfassembly structures on a nanometer scale. This unique characteristic has been utilized for preparation of the materials composed of nanometer pores. [1][2][3][4][5][6][7][8][9][10][11] However, such an application of block copolymer is often limited to ultrathin films. Its restricted longitudinal space induces the periodic arrangement of the phase separations, which spreads over a lateral direction parallel to the surface. 1,3,7,8,11 In this work, we demonstrate an easy method of preparing a nanoporous polyethylene film having submillimeter thickness from a block copolymer precursor.The block copolymer exhibits various types of microphase separations, including spherical, cylindrical, and lamellar structures, depending on the component ratio of the different blocks. Among these morphologies, the sphere is most widely used as a precursor of nanoporous materials. Recently, Yokoyama et al. 9 developed a pore preparation method with supercritical CO 2 , which remains in the spheres and expands, giving numerous nanopores within the sample. A cylinder can also be converted to the continuous pore structure when it can be removed. Hillmyer et al. 4,5,10 prepared nanoporous materials from polystyrene (PS)/poly(lactic acid) (PLA), poly(cyclohexyl ethylene)/ PLA, or PS/poly(ethylene oxide) (PEO) diblock copolymers by

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