Photon Factory Activity Report 2016 #34 (2017)

BL-6A, BL-10C/2015G076

Structure Transition of Bio-Based Polyester Derived fromIsomannide and Succinic Acid Revealed bySynchrotron WAXD/SAXS Simultaneous Measurements
Hironori Marubayashi,* Takaaki Ushio, and Shuichi Nojima
Department of Chemical Science and Engineering, School of Materials and Chemical Technology,
Tokyo Institute of Technology, 2-12-1-H-125 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
1 Introduction“Bio-based plastics” have attracted increasing attention
as alternatives to petroleum-based plastics because ofgreat concern about fossil fuel depletion and global
warming [1]. Isohexides are bio-based cyclic diols thathave three stereoisomers differing in directions of twohydroxyl groups—isosorbide, isomannide, and isoidide.
Bio-based polyesters composed of isohexides and diacids
show a wide variety of properties and biodegradability,
depending on the diol stereoisomerism and the alkylene
chain length [2,3]. However, the crystallization ofisohexide polyesters is still not well-understood, so that
their possibility as crystalline plastics still remains
unexplored. We have investigated the development ofcrystal and lamella structures in the polyester composedof isomannide and C4 diacid units (M4), which possesses
crystal polymorphism (α- and β-forms), by synchrotron
WAXD/SAXS simultaneous measurements [4]. In thisstudy, we examine the structure transition of M4 α-form
during a heating process by synchrotron WAXD/SAXS
simultaneous measurements.
2 Experiment
Isomannide and succinyl chloride were polycondensed
in bulk to M4 polyester with Mn = 104 and Mw/Mn = 2.1.
M4/chloroform solution was cast to obtain a crystallized
sample with only the α-form crystals.
WAXD/SAXS simultaneous measurements wereperformed at KEK PF BL-6A (λ = 0.1500 nm) and BL10C (λ = 0.1488 nm) using an FP84HT TA Microscopy
Cell (METTLER) for heating from 30 to 210 °C at10 °C/min. Sample was packed in a washer, whose
temperature was measured by a resistance temperaturedetector. WAXD/SAXS analyses were done using thehandmade software [5].
3 Results and Discussion
Fig. 1 depicts changes of WAXD curves of M4 during
a heating process at 10 °C/min. Fig. 2 shows changes oftotal crystallinity (Χc, black), the strongest-peak area ofthe α-form (Aα, blue), and that of the β-form (Aβ, red) ofM4 during a heating process at 10 °C/min. Χc (α- and βforms) and Aα drastically decrease at temperatures ≥160 °C. Simultaneously, the peak of β-form appears,
though its area (Aβ) is very small. Here, Aα is comparable
to Aβ, if Χc (α) is similar to Χc (β). These results indicatethat the transition mechanism from α- to β-forms is themelt-recrystallization, not the solid-solid transition.

Fig. 1: Changes of WAXD curves of M4 during a heatingprocess at 10 °C/min. M4 initially has only the α-form.

Fig. 2: Changes of total crystallinity (Χc, black), thestrongest-peak area of α-form (Aα, blue), and that of βform (Aβ, red) of M4 during a heating process at
10 °C/min. Temperature range of 160–185 °C is coloredwith red, at which the β-form is selectively formed.
Acknowledgement
This work was supported by JSPS KAKENHI Grantin-Aid for Young Scientists (B) 26740040 (H.M.).
References[1] T. Iwata, Angew. Chem. Int. Ed. 54, 3210 (2015).
[2] F. Fenouillot et al., Prog. Polym. Sci. 35, 578 (2010).
[3] M. Okada et al., J. Appl. Polym. Sci. 62, 2257 (1996).
[4] H. Marubayashi et al., PFACR 33, 149 (2016).
[5] (a) H. Marubayashi et al., Macromolecules 45, 1384
(2012). (b) H. Marubayashi et al., Macromol. Chem. Phys.
214, 2546 (2013).
* marubayashi@polymer.titech.ac.jp