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摘要
The aggregation behavior of the triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (L64, PEO13PPO30PEO13) in the room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim] [BF4]) was investigated using polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and Fourier transform infrared (FTIR) spectroscopy. The phase diagram of the L64/[Bmim] [BF4] system is described, where the micellar phase (L-1), a mixture of lamellar liquid crystalline (L-alpha) and L-1 phases, the L-alpha phase, a mixture of L-alpha and reverse micellar (L-2) phases, and the L-2 phase are sequentially mapped. Among these phases, the behavior of the L-alpha phase formed in the L64/[Bmim][BF4] system in the L64 concentration region of 40%-65% (w, mass fraction) was focused on because it forms highly-ordered structures. The Maltese cross texture was found through POM characterization, and was typical for the L-alpha phase. The SAXS patterns further confirm the formation of the L-alpha phase. In addition, the lattice spacings of the L-alpha phase were obtained from the SAXS patterns. The effect of temperature on the microstructure of the L-alpha phase was also elucidated. As the temperature was increased, the lattice spacing and ordering of the L-alpha phase increased, while the interfacial area decreased for a certain temperature range. However, the birefringence of the L-alpha phase disappeared when the temperature reached a certain level, which was attributed to the breakdown of hydrogen bonding between [Bmim] [BF4] and poly(ethylene oxide) chains, so the ordering of the L-alpha phase was decreased. The formation mechanism of the L alpha phase is also discussed. Hydrogen bonding, electrostatic and solvophobic interactions are believed to be the main driving forces for the formation of L-alpha phase in the L64/[Bmim][BF4] system.
- 出版日期2012-6
- 单位防灾科技学院
