| 초록 |
Formation of changes of higher-order structure of poly(ethylene glycol)-poly(butadiene) block copolymers (PEG-PBd) in isothermal crystallization from microphase-separated melts were studied using time-resolved synchrotron small-angle X-ray scattering (SR-SAXS) techniques. Lamellar microphase structure of PEG-PBd with weight fraction of fPEG=0.51 was destroyed on crystallization and changed to a lamellar structure distinct from that in the melt. A block copolymer with fPEG=0.34 crystallized keeping the cylindrical structure in the melt. On the other hand, a fPEG=0.7 copolymer whose melt structure was cylindrical showed two kinds of structure changes: at low crystallization temperatures Tc the SAXS peak positions changed discontinuously but the structure remained cylindrical, while the structure changed from cylindrical to lamellar at high Tc. These results suggest that the structure can be changed depending on melt structure as well as a segregation degree of melt microphase-separation. The structure formation of polystyrene-polyethylene block copolymers (PS-PE) was also studied. Because PS-PE was crystallized in the glassy state of PS, that is, from frozen microphase-separated melts, the SAXS peak position did not change in crystallization, which suggests that crystallization occurred within the melt microdomain.
|
