The aim of the present study was to control entanglements in order to regulate the properties of polymeric solids. Initially, fabrication of polymeric solids with few entanglements was attempted. Films of the DNA-cationic surfactant, cetyltrimethylammonium bromide (CTAB) (DNA-CTA), were cast from ethanol solution at room temperature. Morphological examination of DNA-CTA complex films using atomic force microscopy (AFM) revealed that these films were constructed by particle-like substances. Geometrical analysis of AFM images showed that the particle-like substances were the aggregates of several DNA-CTA globules. Mechanical characterization suggested that there were fewer entanglements than with normal plastic films. Small angle X-ray scattering experiments during annealing indicated that molecular motions were highly excited in the surface region of each particle. In conclusion, a globular polymeric film with fewer entanglements was fabricated. V C 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 730-738 KEYWORDS: cationic surfactant; DNA; entanglements; globular solid; mechanical properties INTRODUCTION Interactions in polymer chain systems involve both electrostatic and geometrical interactions. As the concentration of polymer molecules in a solution increase during the preparation of polymeric solids by, for example, casting, the interpenetration of polymer chains occurs and entanglements, representing the geometrical interaction, are constructed provided the molecular weight of the polymer is greater than the critical molecular weight for entanglement. These entanglements result in homogeneous solid properties with a characteristic relaxation spectrum. The solid state properties of polymeric materials change with temperature and molecular weight, and are governed by the quantity and quality of the entanglements.1-3 The amount of chain entanglements is auto-

We investigated that the effect of demineralization on the hierarchical structure of bovine femur by means of simultaneous synchrotron radiation wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) measurement. The azimuthal intensity distributions at the 2θ of (002) WAXD reflection of bones with various degrees of demineralization obtained as a function of demineralization time (t i ) indicate that the orientation of HAp micro-crystals is independent on the mineral fraction. The SAXS diffraction peaks due to the long period between the minerals deposited to the gap region of collagen fibrils were observed in the SAXS profiles for the intact bone and partially demineralized bones (PDBs). The ratio of the SAXS peak intensity of first-order diffraction to that of third-order diffraction was independent on the t i . The result indicates that the minerals deposited into the gap region of collagen fibril are homogenously demineralized in the 0.5 M EDTA solution. The SAXS profiles in the direction perpendicular to the bone axis suggest that the higher-order structure of bone was not affected by the demineralization up to t i = 2 h, whereas that was degraded at t i = 3.5 h.