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Structural changes during the drawing and shrinking of linear low-density polyethylene (LLDPE) film are analyzed through in-situ X-ray measurements. A synchrotron radiation source enables simultaneous analyses combining small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). During drawing, the original unoriented SAXS and WAXD patterns transformed into line and spot patterns, indicating the orientation of both lamellar stacking and the molecular axis along the drawing direction. During the subsequent shrinking these patterns are retained, suggesting the tilted lamellar and molecular chains. A possible model for structural changes indicates that tie molecules between lamellae effectively transmit drawing and shrinking stresses, which contributes to desirable actuation properties. [ABSTRACT FROM AUTHOR]

The nanometer-size crystallization of poly(3,4-ethylenedioxythiophene)(PEDOT) inside the hydrophobic core region of PEDOT:PSS (PSS: poly(4-styrenesulfonate))in a solid film is found by small and wide-angle X-ray scatteringsusing a synchrotron radiation source. The clarified PEDOT:PSS structureindicates that a nanocrystal of PEDOT surrounded by PSS is grown inthe solid film from randomly oriented PEDOT in a micelle dispersedin water during the course of film fabrication. The addition of ethyleneglycol (EG) to the PEDOT:PSS water dispersion and post-treatment ofthe pristine film with EG both provide similar improvements in PEDOTcrystallinity. The crystallite size of PEDOT increases up to a comparablesize (∼4.8 nm) to the hydrophobic PEDOT core region of themicelle. The electrical conductivity of the solid film is concurrentlyenhanced by 2 orders of magnitude with the growing nanocrystal ofPEDOT. These findings clearly demonstrate the importance of the singlecrystalline PEDOT assisted by EG to obtain high electrical conductivityof the PEDOT:PSS solid film. [ABSTRACT FROM AUTHOR]

It was found that a comb-like complex consisting of poly[2-(N,N- dimethylamino)ethyl acrylate] (PDAEA) and p-dodecylbenzene sulfonic acid (DBSA) formed mesomorphically ordered lamellar phase at room temperature where PDAEA and DBSA are in molten state. The lamellar phase shows optical anisotropy, although the individual components are always isotropic. In addition it is found that the optical anisotropy of the PDAEA-DBSA complex completely disappears with accompanying order-disorder transition of the lamellar morphology with elevating temperature. [ABSTRACT FROM AUTHOR]

Abstract: Direct determination of the discrete distribution for crystalline lamellar thickness has been performed for poly( d , l -lactic acid)/poly(oxyethylene) (PDLLA/PEG) blends by conducting small-angle X-ray scattering (SAXS) measurements using synchrotron radiation. The PDLLA used was an random (racemic) copolymer of bio-based poly( l -lactic acid) (PLLA) and poly( d -lactic acid) (PDLA) with the lactide monomer ratio of l : d = 50:50. It is known that PLA is miscible with PEG in the amorphous state. In the current paper, we report comprehensive results on structural analyses of PDLLA/PEG blends in the course of heating and cooling process using SAXS to elucidate the change in the thickness distribution of the lamellae. As a consequence, it was found that the distribution of the lamellar thickness moves toward the larger value (in other words, lamellar thickening) as temperature approaches the melting point. Typically, the thickness distribution was dispersed in the range of 10–20 nm at room temperature and it changed toward 40 nm in the vicinity of the melting temperature. To the best of our knowledge, this is the first report of direct determination of the discrete distribution for the crystalline lamellar thickness and their in-situ changes in the course of the lamellar thickening process. As a result, the lamellar thickening was found to occur at much lower temperature for the blend samples with 10% and 20% of PDLLA contents as compared to the PEG 100% sample. This phenomenon can be ascribed to the melting point depression owing to the miscibility between PEG and PDLLA. Thereby, thinner lamellae were melted and thicker ones appeared at much lower temperature for the blends than for the PEG 100% sample. As for the average repeating distance (long period) of the lamellar stacks, an abrupt increase similar to the critical divergence was observed (from 25 nm to 50 nm) in the heating process. Not only for the melting behavior but also in the course of recrystallization, change in the lamellar-thickness distribution was uncovered, which shows strong hysteresis depending on what temperature the sample was cooled down from. [Copyright &y& Elsevier]

[Display omitted] • Structural changes during cyclic stretching/shrinking of drawn LLDPE were analyzed by in-situ measurements. • Macroscopic strain change of the sample film agrees with microscopic tie-molecular stretching and shrinking. • Temperature actuation is also driven by stretching and shrinking of tie molecules. Structural change during cyclic stretching/shrinking of drawn film of linear low-density polyethylene (LLDPE) was analyzed using a combination of in-situ X-ray and NMR measurements. Small-angle X-ray scattering (SAXS) for the original drawn LLDPE film before stretching exhibits a split-layer-line pattern, indicating lamellar tilt. Stretching the film transforms the pattern into the straight-layer-line one, and subsequent shrinking regains the original split-layer-line one. Solid-state 1H-NMR measurements detected three components having different relaxation times for both originally shrunk and subsequently stretched states. Among these components, the intermediate one exhibits reversible change in relaxation time, synchronizing the stretching/shrinking cycles. This component is attributed to tie molecules, bridging the rigid components of crystalline lamellae and accompanying a small amount of the mobile component consisting of unrestricted amorphous chains. Stretching and shrinking such tie molecules induces reversible transformation of the microscopic lamellar arrangements, which causes macroscopic actuation of drawn LLDPE. [ABSTRACT FROM AUTHOR]