Photon Factory Activity Report 2014 #32 (2015) B

BL-10C/2014G011

Higher-Order Structure of Bio-Based Polymers Derived fromIsosorbide and Isomannide Revealed by Synchrotron Small-Angle X-ray Scattering
Hironori Marubayashi,* Takaaki Ushio, and Shuichi Nojima
Department of Organic and Polymeric Materials, Graduate School of Science and Engineering,Tokyo Institute of Technology, 2-12-1-H-125 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
1 Introduction“Bio-based polymers” have attracted increasing
attention as alternatives to petroleum-based polymers
because of great concern about exhaustion of fossil fuels
and global warming [1]. 1,4:3,6-Dianhydrohexitols(DAHLs) are bio-based sugar diols whose rigid cyclic
structure is expected to give remarkable thermal andmechanical properties when introduced into the polymer
backbone [2]. There are three stereoisomers differing in
directions of two hydroxyl groups—isosorbide,isomannide, and isoidide (Fig. 1). Bio-based polyesters
composed of DAHLs and dicarboxylic acids have beensynthesized and their basic properties have beensystematicallyinvestigated[3].
However,thecrystallization of DAHL polyesters is still not wellunderstood. Previously, the higher-order structure ofDAHL polyesters with C10 dicarboxylic acid units(DAHL-10) was analyzed by using synchrotron smallangle X-ray scattering (SR-SAXS) [4]. In this study, weinvestigate the higher-order structure of DAHL polyesters
with C12 carboxylic acid units (DAHL-12) by SR-SAXS
and compare with that of DAHL-10.

3 Results and Discussion
Fig. 3a shows SAXS curves of DAHL-12 isothermallycrystallized at 30 °C. Scattering peaks can be seen forboth IS12 and IM12, indicating the formation of the longperiod structure consisting of crystalline lamellae andamorphous layers. The long period L of IM12 (10.8 nm)
is larger than that of IS12 (10.2 nm). Their correlation
functions (Fig. 3b) indicate that the lamella thickness lc of
IM12 (3.6 nm) is larger than that of IS12 (2.8 nm), while
there is almost no difference in the amorphous layer
thickness la between IM12 (7.2 nm) and IS12 (7.4 nm).
The same magnitude relationship is true for theparameters of the long period structure (L, lc, la) ofDAHL-10. These results should be linked with a longer
fiber period of IMn compared with ISn (n = 10 or 12), i.e.,a conformational difference in the crystallized state.

Fig. 1: Chemical structures of 1,4:3,6-dianhydrohexitols(DAHLs). The endo and exo C–O(H) bonds are shown in
red and blue, respectively.
2 Experiment
Commercially-available DAHLs (isosorbide andisomannide) were polycondensed with dodecanedioyl
dichloride. As a result, two types of DAHL polyesters
were obtained with Mn ≈ 1.3 × 104 and Mw/Mn ≈ 1.9 (Fig.
2). Polyesters containing isosorbide and isomannide units
were named IS12 and IM12, respectively. Meltcrystallization treatments were done for sufficient time tocomplete the crystallization of as-polymerized samples.

Fig. 2: Polyester composed of DAHL (shown in blue) andC12 dicarboxylic acid units.
SAXS measurements were performed at KEK PF BL10C (λ = 0.14880 nm). SAXS analyses were done using
the handmade software developed by Marubayashi [5].

Fig. 3: (a) SAXS curves and (b) normalized onedimensional correlation functions of DAHL-12 meltcrystallized at 30 °C for 15 h.
Acknowledgement
This work was supported by JSPS KAKENHI Grantin-Aid for Young Scientists (B) 26740040 (H.M.).
References[1] Iwata, T., Angew. Chemie Int. Ed. 54, 3210 (2015).
[2] Fenouillot et al., Prog. Polym. Sci. 35, 578 (2010).
[3] Okada et al., J. Appl. Polym. Sci. 62, 2257 (1996).
[4] Marubayashi et al., Photon Factory Activity Report 31,237 (2014).
[5] (a) Marubayashi et al., Macromolecules 45, 1384
(2012). (b) Marubayashi et al., Macromol. Chem.
Phys. 214, 2546 (2013).
* marubayashi@polymer.titech.ac.jp