Photon Factory Activity Report 2005 #23 Part B (2006)
Materials Science

10C/2005G191

Simultaneous DSC-SAXS measurement of PEO-b-PMA(Stb) copolymers
1Takeshi YAMADA1, Severine BOYER1,2, Hirohisa YOSHIDA*1,2
Graduate School of Urban Environmental
Science, Tokyo Metropolitan University, Hachiouji, Tokyo
192-0397, Japan, 2JST (CREST), Kawaguchi, Saitama 332-0012, Japan

Introduction
Di-block copolymers form the nano-scale orderedstructure due to phase separation as an equilibrium state.
We have reported the phase transitions and the nano-scaleorder structure of amphiphilic di-block copolymersconsisted of hydrophilic poly(ethylene oxide) (PEO) andhydrophobic poly(methacrylate) derivatives PMA(R)containing liquid crystalline mesogen unit (R) as an ester[1-3]. In the case of di-block copolymer having
azobenzene as a mesogenic unit, both smectic C and A
were observed on heating by the simultaneous DSCSAXS measurement. In this study, the nano-scale
structure and liquid crystalline state of amphiphilic diblock copolymer having stilbene moieties as mesogenicunit, PEO114-b-PMA(Stb)n.
Experiments
Materials
PEO114-b-PMA(Stb)n used through the experiments wasprepared by the atom transfer radical polymerization. The
degree of polymerization of PMA(Stb), n, was1determined by H-MNR, and .the molecular weightdisparity Mw/Mn determined by GPC was less than 1.1.
Methods
The simultaneous DSC-XRD measurements [4] wereperformed by SAXS optics at BL-10C, PF, KEK. The
wavelength of X-ray and the measurement range of-1
scattering vector were 0.1488 nm and 0.06 nm < q-1(=4πsinθ/λ) < 3 nm , respectively. DSC scanning rate and-1
XRD time resolution were 2 K min and 30 sec,respectively.
Results
Nano-scale structure
The SAXS profile change of PEO114-b-PMA(Stb)45
obtained by DSC-SAXS on heating was shown in Fig.1.
DSC indicated three endothermic peaks at 40, 140 andoo
160 C, the endothermic peak at 40 C was assigned to themelting of PEO segment. The SAXS profiles of PEO114-bPMA(Stb)n showed the scattering peaks in the q range
-1
1/2
1/3
from 0.3 to 1.0 nm , these peaks (at q*, q* , 3q* , and2q*) indicated the hexagonal packed cylinder structure forPEO114-b-PMA(Stb)n with n = 26 – 75, however, PEO114b-PMA(Stb)4 formed the lamellar structure. The scattering
1/2
1/3peaks at q* , 3q* , and 2q* became weak above the
1/2
1/3
melting of PEO, and the peaks at q* , and 3q* appearedoagain at 170 C. These nano-scale structures observed atvarious temperatures were almost the same with those of144

Users' Report

PEO114-b-PMA(Az)n, which contained azobenene moieties
as liquid crystalline mesogenic units [2, 3].
Liquid crystalline phase-1In Fig.1, the scattering peak at 1.8 nm wascorresponded to the smectic layer of hydrophobicPMA(Stb) domain. The q value of smectic layer wasconstant below the melting temperature of PEO, ando
increased in the temperature range from 100 to 140 C.
The q value and its intensity of smectic layer decreased ino
the temperature range from 140 to 160 C, and thisscattering peak disappeared at the endothermic DSC peakoat 160 C. From this result, the endothermic DSC peak ato160 C was assigned as the isotropic transition of PEO114b-PMA(Stb)45. In the case of PEO114-b-PMA(Az)n, twotypes of smectic phase, SC and SA were observed and thetransition between SC and SA was measured thermoreversibly. Furthermore investigations are proceeding toassign the type of liquid crystalline state of PEO114-bPMA(Stb)n.

Fig.1 SAXS profile change of PEO114-b-PMA(Stb)45 on
heating

References[1] H. Yoshida et al., Trans. Mat. Res. Soc. Japan, 29, 861(2004).
[2] T. Yamada et al., Trans. Mat. Res. Soc. Japan, 30, 675(2005).
[3] S. Y. Jung et al., Colloids & Surface A, in press (2006)[4] H. Yoshida et al., Thermochimica Acta, 264, 173(1995)* yoshida-hirohisa@c.metro-u.ac.jp