1996 Fiscal Year Final Research Report Summary
Studies of Phase Transition in Block Copolymer Solutions by Small-Angle Light Scattering Spectroscopy
| Project/Area Number |
07555604
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 試験 |
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| Research Field |
高分子構造・物性(含繊維)
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TSUNASHIMA Yoshisuke Kyoto University, Institute for Chemical Research, Associate Professor, 化学研究所, 助教授 (30089130)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAMURA Toshihiko Unisoku, Ltd, Scientific Equipments Developing Laboratory, Director, 科学機器開発研究所, 所長
HIRAI Asako Kyoto University, Institute for Chemical Research, Associate Instructor, 化学研究所, 教務職員 (20156623)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Diblock copolymers / Selective solvents / Phase separation / Micellar formation / Intramicelle motions / Core-shell structures / Phase transition / Small-angle light scattering |
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| Research Abstract |
A high-speed light scattering spectroscopy system which measures molecular motions appearing in the phase separation and/or the phase transition of block copolymers in solution was constructed, in which the molecular motions detectable are ranging from 10^<-8> to 10^3 second in the magnitude of the relaxation times. At the scattering angles rheta in the range of usual 30-150ﾟ and at rheta smaller than 10ﾟ, phase transitions on polystirene (PS)-block-poly (methyl mathacrylate) diblock copolymer of high molecular weight such as M^w=1.53*10^6 (38.5wt%PS) were investigated in selective mixed solvents of benzene (BZ) and p-cymene (PC) as a function of the mixed ratios and the temperature differences in the temperature jump. When measured at rheta=30-150ﾟ, the diblock copolymer were found to form a monodispersed micelle at the mixed ratio more than 60 vol% of PC and to be in apparent closed association equlibrium between the single copolymer (unimer) and the micelle. The micelle dynamics was
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charcterized by its vast internal motions which occur inside the micelle. The intramicellar motions were attributed to active hydrodynamic heterocontacts between PS and PMMA subchain elements, or the composition fluctuation. At smaller angles as 5-10ﾟ, however, the scattering intensity of the solution fluctuated at the time interval as small as mus, the absolute intensity varing in three order of magnitude. Dynamic light scattering (DLS) from these solutions in quiescent state made clear that the intensity fluctuations were originated from structures whose sizes varing quickly in one to five order to magnitude ; the fuge micellar structures observed are considered not of be stable but transient ones, which are created and disappear in very short time intervals. DLS under Couette flow ascertained this picture with the result that only a single copolymer was observed in the shear field. The temperature difference of 20-80ﾟC induced no detectable conformation change in the present diblock copolymer chain. Less
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