Structural Transition of Poly[(R)-3-hydroxybutyrate-co-(R)-3- hydroxyvalerate] Single Crystals on Heating As Revealed by Synchrotron Radiation SAXS and WAXD

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• 作者：Tomoharu Sawayanagi ; Toshihisa Tanaka ; Tadahisa Iwata ; Hideki Abe ; Yoshiharu Doi ; Kazuki Ito ; Tetsuro Fujisawa ; Masahiro Fujita
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：April 3, 2007
• 年：2007
• 卷：40
• 期：7
• 页码：2392 - 2399
• 全文大小：569K
• 年卷期：v.40,no.7(April 3, 2007)
• ISSN：1520-5835

文摘

The annealing behavior of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)) crystal was studied by synchrotron radiation small-angle X-ray scattering (SAXS) and wide-angle X-raydiffraction (WAXD). Solution-grown single crystals of P(3HB-co-3HV) with various composition of 3HV (5.3-16.0 mol %) were used in order to examine the effect of 3HV unit on the structural changes on heating. Thetwo-dimensional (2D) SAXS patterns demonstrated that the lamellar thickness of P(3HB-co-3HV) single crystalstarts to increase discontinuously at an annealing temperature and that two populations with two different thicknessesof original and reorganized crystals coexist in a temperature range, independent of 3HV composition. This factmeans that the 3HV unit with longer side chain does not hinder the jump of lamellar thickness. The 2D WAXDand differential scanning calorimetric experiments indicated that the discontinuous thickening is caused by partialmelting and recrystallization. The depression of transition temperature from the original crystal to the thicker oneand the incompletion of reorganization with increase in 3HV unit can be attributed to the lowering of the interactionbetween the copolymer chain stems and to the difficulty in incorporation of the chains to crystal lattice, respectively.